The
The Orange Book
Publisher
Tetra Pak Processing Systems AB SE-221 86 Lund, Sweden. www.tetrapak.com
ISBN 91-3428-4 Further copies of The Orange Book can be obtained from your local Tetra Pak company. Editor
Ulla Ringblom Production
Pyramid Communication AB Printer: Ruter Press Printed in 2004 ©
Copyright
No part of The Orange Book may be duplicated in any form without the source being indicated (Tetra Pak). To the best of our knowledge the information presented in this book is correct. Nevertheless, Tetra Pak disclaims all responsibility for any detrimental effects resulting from the way in which the information is used.
I
II
Sharing an experience A mine of information
Because of its refreshing taste and wholesome nature, orange juice dominates the fruit juice market. It is unique among juices in that the consumer can easily compare its sensory properties with those of the fresh fruit or juice squeezed directly from fresh oranges. This puts high demands on orange juice producers to deliver the same level of quality, or as near as possible, as that consumers expect from fresh fruit. The challenge is particularly tough because orange juice is a complex beverage sensitive to the way it is treated. Over the years, Tetra Pak has been closely involved with orange juice products. We believe that some of this experience could also be of interest to our customers. As a supplier of both processing equipment and packaging systems, Tetra Pak has hands-on competence with all steps in the production chain, from the fruit tree to the distribution of packaged orange juice. This is what we would like to share with you in the form of this book.
From bulk concentrate and onwards, much of what is described in The Orange Book is also valid for orange nectars and other types of fruit juices. However, the production requirements for pure orange juice are usually more stringent in order to satisfy consumer expectations for this product. This book focuses solely on orange juice, but Tetra Pak also has extensive know-how in the processing and packaging of many other types of fruit juices. A number of tools help you extract information readily from this book. A glossary explains familiar expressions used in the citrus industry, and a list of literature is given for further reading. Metric units are used throughout this book except when other specific units are commonly used. A list of conversion factors allows you to convert between different units. We hope you will find The Orange Book useful in providing consumers with the most enjoyable fruit juice provided by nature.
A journey with juice
Second edition
The Orange Book follows the complete journey of orange juice. It begins with the various types of orange fruit, proceeds through all the processing and packaging steps, and ends with the distribution of the end product to consumers. Along the way there is a chance to look at market information, juice quality and categories, the trading and shipping of products, and industry standards and regulations. Consideration is given throughout to the factors that influence end-product quality, including the role of flavour and product blending.
The first edition of The Orange Book was well received in 1997, and as it went out of print it is followed by this revised edition. Valuable comments have been received on the book from many sources in the citrus industry. Tetra Pak would particularly like to thank the following persons for their review of relevant sections in the book and suggestions on how to improve it: Professor Robert Braddock of the University of Florida, Antonio Carlos Gonçalves of Louis Dreyfus Citrus, Dr. Barrie Preston of Döhler-Eurocitrus, and Martin Greeve, Chairman of the AIJN Code of Practice Expert Group.
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Contents 1. THE ORANGE FRUIT AND ITS PRODUCTS
1
1.1 The fruit’s origin and important varieties
2
1.2 A global overview 1.2.1 Large-scale development 1.2.2 Orange crop diseases
3 4 4
1.3 Bridging the seasons
5
1.4 Fruit selection
6
1.5 Inside an orange
6
1.6 Squeezing out every drop
7
1.7 Primary and secondary products
8
1.8 Major orange-producing regions 1.8.1 Brazil 1.8.2 Florida
10 10 12
1.9 Other regions
13
2. ORANGE JUICE QUALITY AND CATEGORIES
17
2.1 Juice quality 2.1.1 Defining quality 2.1.2 Quality specifications
18 18 19
2.2 Important properties of orange juice 2.2.1 Sugars and acids 2.2.2 Cloud and pulp 2.2.3 Flavour 2.2.4 Colour 2.2.5 Promoting health
20 20 22 23 25 26
2.3 Orange juice categories 2.3.1 Ready-to-drink orange juice 2.3.2 Concentrated orange juice
28 28 29
2.4 Regulations governing juice origin
30
3. THE SUPPLY CHAIN AND GLOBAL CONSUMPTION OF ORANGE JUICE
31
3.1 The chain of supply 3.1.1 Growers 3.1.2 Types of fruit processor 3.1.3 Blending houses 3.1.4 Juice packers 3.1.5 Soft drink producers
32 33 34 35 36 37
3.2 World market pricing for bulk juice products
37
3.3 FCOJ commodity trading and the futures market
38
3.4 Import duties and juice imports 3.4.1 Import duties with some typical examples
39 41
IV
3.5 Global orange juice consumption 3.5.1 Per capita orange juice consumption
42 43
4. PRINCIPLES OF PROCESSING ORANGE JUICE
45
4.1 Impact of processing on juice quality 4.1.1 Raw materials 4.1.2 Processing 4.1.3 Impact of long-term bulk storage
46 47 47 49
4.2 Air/oxygen in the product 4.2.1 Sources of air/oxygen 4.2.2 Problems caused by air/oxygen in the product 4.2.3 Principles of deaeration
50 51
4.3 Microbiology of orange juice 4.3.1 Relevant microorganisms in orange juice 4.3.2 Microflora of different types of orange juice 4.3.3 Influence of raw materials 4.3.4 Sanitation
54
4.4 Pasteurisation 4.4.1 Purpose of pasteurisation 4.4.2 Inactivation of enzymes 4.4.3 Inactivation of microorganisms 4.4.4 Time-temperature conditions for pasteurisation
59 59 59 61
5. FRUIT PROCESSING
63
5.1 Processing plant overview
64
5.2 Orange juice production steps
66
5.3 Fruit reception
67
5.4 Juice extraction 5.4.1 Extractor types 5.4.2 The squeezer-type extractor 5.4.3 The reamer-type extractor 5.4.4 Down stream of the juice extractors
68 68 69 71
5.5 Clarification
72
5.6 NFC production 5.6.1 Oil reduction 5.6.2 Primary pasteurisation 5.6.3 Deaeration 5.6.4 Long-term frozen storage 5.6.5 Aseptic storage in tanks 5.6.6 Aseptic storage in bag-in-box containers 5.6.7 Reprocessing of NFC
74 75 76 76 76 77
52 53
54 57 58 58
61
72
78 78
Contents
5.7 Concentrate production 5.7.1 Tubular evaporator systems 5.7.2 Plate evaporator systems 5.7.3 Homogenisation 5.7.4 The centrifugal evaporator 5.7.5 Essence recovery 5.7.6 Concentrate storage 5.7.7 Alternative concentration methods
79 79 80 81 82 82 83 83
5.8 Peel oil (cold-pressed oil) recovery 5.8.1 Straining and concentration step 5.8.2 Polishing 5.8.3 The winterisation process 5.8.4 d-Limonene recovery systems
84 84 85 85 85
5.9 Feed mill operations
86
5.10 Pulp production 5.10.1 Production factors which affect commercial pulp quality 5.10.2 Process steps in pulp production
87 88 88
5.11 Pulp wash production
92
5.12 Essence recovery
92
6. TRANSPORT AND HANDLING OF BULK PRODUCTS
93
6.1 Packing and shipping preferences
95
6.2 Bulk shipping of FCOJ 6.2.1 From Brazil to Europe
95 96
6.3 Bulk shipping of NFC 6.3.1 Frozen NFC shipments 6.3.2 Bulk units for aseptic NFC shipments 6.3.3 Bulk shipping of aseptic NFC by sea 6.3.4 Transport of bulk product versus retail packaged product
97 97
7.
7.1 An overview of juice packer operations 7.1.1 General requirements for juice packer lines 7.1.2 Process lines 7.2 Raw material reception and handling 7.2.1 Tanks for concentrate storage 7.2.2 Drums with frozen concentrate 7.2.3 Drums containing solid frozen products 7.2.4 Aseptic bag-in-box containers 7.2.5 Tanks for NFC 7.2.6 Reclaim product
97 99 99
6.4 Shipping costs
100
6.5 Terminals for receiving orange juice 6.5.1 Terminals for bulk FCOJ 6.5.2 Terminals for bulk aseptic NFC
100 100 101
6.6 Blending house operations
102
PROCESSING AT THE JUICE PACKER
V
103 105 105 105 110 110 111 111 112 112 112
7.3 Water treatment 7.3.1 Water quality 7.3.2 Water treatment methods 7.3.3 In-plant distribution of product water 7.3.4 Deaeration of water
113 113 114
7.4 Blending 7.4.1 Blending of nectars and fruit drinks 7.4.2 Defining the blending formula 7.4.3 Savings made by accurate blending 7.4.4 Comparison of blending methods 7.4.5 Batch blending systems 7.4.6 In-line blending systems 7.4.7 How a refractometer works 7.4.8 How a density meter works
116 116 117 118 118 119 120 121 122
7.5 Pasteurisation and deaeration 7.5.1 Selecting the heat exchanger 7.5.2 The pasteurisation process 7.5.3 Deaeration 7.5.4 System design 7.5.5 Process control 7.5.6 Control of pasteurisation units
122 123 124 125 126 126 127
7.6 Aseptic buffer 7.6.1 Operational steps
128 129
7.7 Hot filling 7.7.1 Process description
129 130
7.8 Aseptic transfer of NFC
130
7.9 Cleaning-in-place 7.9.1 CIP procedures 7.9.2 Pigging
131 132 133
7.10 Quality control of final product 7.10.1 Microbiological control
134 134
115 116
Contents
8. ADD-BACK COMPONENTS – VOLATILE FLAVOURS AND FLOATING PULP
135
8.1 Volatile flavours 8.1.1 Origin of natural volatile orange flavours 8.1.2 Major constituents of flavour fractions 8.1.3 Flavour standardisation and folding of oils 8.1.4 Methods of separating and concentrating flavours 8.1.5 Creation of flavour systems
136
8.2 Floating pulp 8.2.1 Useful terms 8.2.2 Floating pulp properties 8.2.3 Floating pulp concentration
142 142 144 145
8.3 Components added back to juice
146
9. PACKAGING AND STORAGE OF ORANGE JUICE
149
139
10.2 Orange juice at the retailer 10.2.1 Distribution units 10.2.2 Handling at the retailer
140 141 142
151
9.2 Barrier properties against oxygen 9.2.1 Vitamin C degradation 9.2.2 Colour changes 9.2.3 The impact of oxygen on storage-dependent flavour changes
152 152 154
9.3 Barrier properties against light
156
9.4 Barrier properties against aromas 9.4.1 Composition of orange juice aroma 9.4.2 Properties of different polymers 9.4.3 Properties of different packages 9.4.4 Consequences of flavour scalping
156 156 157 158 159
9.5 Aseptic versus nonaseptic packaging
160
167
10.1 Distribution of product to retailer 169 10.1.1 Delivery directly to the retail store 169 10.1.2 Delivery through wholesalers 169 10.1.3 Delivery to a retailer’s central depot 170
137
9.1 The role of packaging 9.1.1 Product quality parameters to be protected during storage 9.1.2 Factors affecting quality parameters during storage
9.6 Different packages and packaging systems 9.6.1 Carton-based packages 9.6.2 Bottles 9.6.3 Hot filling 9.6.4 Selecting the most appropriate package for a particular juice
10. FROM JUICE PACKER TO CONSUMER
171 171 172
10.3 The orange juice consumer 174 10.3.1 Regional preferences for juice categories 174 10.3.2 Who buys juice in the USA 176 10.3.3 When orange juice is consumed 176 10.3.4 Where orange juice is consumed 177 10.3.5 Why people buy orange juice 178 10.4 Orange nectars and orange drinks 179 10.4.1 Fruit nectars 179 10.4.2 Still fruit drinks 179 11. STANDARDS AND REGULATIONS
151 151
154
160 161 163 165
181
11.1 Standards governing juice composition and labelling 11.1.1 The USA and Canada 11.1.2 The European Union 11.1.3 Other major regions and countries 11.1.4 Fruit juice standards of Codex Alimentarius
182 183 184 186
11.2 The problem of adulteration 11.2.1 Protecting the consumer 11.2.2 Telling wrong from right
188 188 189
12. GLOSSARY
191
13. ABBREVIATIONS, WEIGHTS AND MEASURES
197
13.1 Abbreviations
197
13.2 Unit conversions
198
187
13.3 Density tables for sugar solutions 199
166
VI
14. FURTHER READING AND REFERENCES
201
14.1 Books on orange juice
201
14.2 References
202
14.3 Useful websites
204
INDEX
205
1
The orange fruit and its products
In section 1 you will read about: • The origin and spread of the orange plant from Southeast Asia to the rest of the world. • Global orange production and the development of large-scale production. • Common orange crop diseases and their control by using resistant rootstocks. • The whys and wherefores of single-strength and concentrated juice.
• How the seasons are bridged to provide consumers with year-round supplies. • What’s inside an orange. • Nature’s gift. Every part of the orange can be used for producing commercial products. • Valuable by-products such as pulp, peel oil, essences and animal feed. • The most important orange-growing regions.
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1. The orange fruit and its products A look inside Basically, an orange consists of juice vesicles surrounded by a waxy skin, the peel. The peel comprises a thin, coloured outer layer called the flavedo and a thicker, fibrous inner layer called the albedo. The endocarp, the edible portion of the fruit, includes a central fibrous core and individual segments containing the juice sacs. In large processing plants the complete fruit is utilised. By-products are produced to help maximise profits and minimise waste.
Summary The orange plant originated in Southeast Asia and spread gradually to other parts of the world. Today, orange juice products derive from four main groups of orange. About 65 million tonnes of oranges per annum are produced globally. Of this, around 40 % is processed into juice and the rest consumed as whole fruit. Single-strength or concentrated As juice is produced on a seasonal basis, it must be stored between seasons to ensure a year-round supply to consumer markets. Most juice is produced as frozen concentrated orange juice, FCOJ, because it can be stored for long periods of time and shipped at lower cost as it contains less water. “Not-from-concentrate” juice, NFC, which is at single strength, requires much larger volumes during storage and shipping. Most NFC produced is intended for nearby markets but its export is increasing.
Major players The two most important orange-processing regions are Brazil and the state of Florida in the US. Together these regions account for nearly 90 % of global orange juice production.
Tangerines 17 %
Lemons / Limes 11 %
1.1 The fruit’s origin and important varieties The orange is the world’s most popular fruit. Like all citrus plants, the orange tree originated in the tropical regions of Asia. Oranges are mentioned in an old Chinese manuscript dating back to 2200 BC. The development of the Arab trade routes, the spread of Islam and the expansion of the Roman empire led to the fruit being cultivated in other regions. From its original habitat, the orange spread to India, the east coast of Africa, and from there to the eastern Mediterranean region. By the time Columbus and his followers took plants to the Americas, orange trees were common in the western Mediterranean region and the Canary Islands.
Grapefruits 6%
Oranges 66 %
Fig. 1.1 World citrus fruit production by types 2001/02. Source: FAO
Oranges account for more than two thirds of the world production of all citrus fruits, of which other important species are the lemon, grapefruit and mandarin (see Figure 1.1).
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1.2 A global overview
Italy Greece California
Spain Turkey
Florida Caribbean Mexico Central America
Israel
Japan China
Egypt
Morocco Brazil
Argentina
Australia
South Africa
Fig. 1.2 The major orange-growing regions.
Four groups of fruit are of commercial significance in the production of orange juice products: • The sweet orange, also known as the China orange, Citrus sinensis • The sour or bitter orange, also known as the Seville orange, Citrus aurantium • The mandarin orange and tangerine varieties, Citrus reticulata • Hybrid oranges (tangors) which result from various crosses between tangerines and sweet oranges.
ripens at a similar time, which allows efficient harvesting and operation of processing plants. However, it also means that trees of the same variety in a grove are susceptible to the same diseases and physiological disorders. As required in different regions, bud wood may be grafted on to rootstocks known to be resistant to certain diseases or drought. During their first few years of growth orange trees do not bear fruit, but when they do, the yield per tree increases gradually until the trees reach maturity at about 10 years old.
Of these, the sweet orange is by far the most important. In several markets, including Europe, only juice made from sweet orange varieties, Citrus sinensis, may be labelled as orange juice. To be cor rect from a horticultural viewpoint, the common name for the species Citrus reticulata is mandarin, some varieties of which are called tangerines. However, the word tangerine is often used as the common species name. Most citrus plants are propagated vegetatively by bud wood cuttings (scions – the top part that controls the type of fruit) grafted on to a different rootstock. This means that trees of the same cultivar are genetically identical and respond similarly to their environment, for example fruit
1.2 A global overview Oranges are cultivated in tropical and subtropical regions around the world. The trees can grow in a wide range of soil conditions, from extremely sandy soils to rather heavy clay loams, although they grow best in intermediate types of soil. Local growing conditions, such as climate, type of soil and grove practices, have a large influence on the quality of fruit produced and on the extracted juice. An orange variety, for example Valencia, may have quite different properties when grown in different parts of the world. The major orange-growing regions are shown in Figure 1.2.
3
1.2 A global overview
120
Approximately 65 million tonnes of oranges are produced per year worldwide. About 40 % of the total tonnage is processed, the rest being consumed as fresh fruit. Whenever possible, growers prefer to sell oranges to the fresh fruit market as their price is normally higher than for fruit sold for processing into juice. In some countries this can lead to a significant variation in the amount of fruit processed from one year to another. Florida and Brazil are the world’s largest fruit producing countries. Here the majority of fruit harvested is processed because the orange varieties in these regions are grown for processing rather than for direct consumption. Due to the planting of new trees, world orange production continued to increase into the early 2000’s – mainly in Florida, Brazil and China. World orange production is also expected to increase further in other regions as a result of improved planting programmes, cultivating techniques, and support given to orange growers. Nevertheless, unwanted climatic effects like frost and storms, along with uncontrolled diseases of fruit trees, could reduce crops and juice yields significantly. Recent years have seen notable fluctuations in world orange production.
Others USA Brazil
Million tonnes
100 80 60 40 20 0 Citrus fruit
Oranges
Oranges for processing
Fig. 1.3 World citrus fruit production and processing, 2001/02. Source: FAO
In 1983 Brazil surpassed Florida as the world’s number one orange producer. However, new trees that were planted further south in Florida in areas less affected by frost are now bearing fruit. This has boosted Florida’s orange production significantly and in years with good yields the state meets most of the US demand for juice. Figure 1.3 shows the estimated world citrus fruit production and processing for the 2001-02 season (mid-01 to mid-02). China has the fastest growth in citrus fruit production as a result of the intensive planting of new trees. So far, most oranges in China are consumed fresh, with only a small amount of fruit being processed. The Mediterranean is an important region for growing high-quality fruit. As more and more Mediterranean oranges are being eaten fresh, juice production is gradually declining in this region.
1.2.1 LARGE-SCALE DEVELOPMENT
Commercial cultivation of oranges intended for large-scale processing into fruit sections and juice began in Florida in the 1920’s. In the late 1940’s, frozen concentrated orange juice for home dilution was developed in the USA. This led to a rapid growth in orange juice consumption. As a result, the cultivation and processing capacity of oranges in Florida grew rapidly. However, severe frosts in Florida drastically reduced fruit yields and killed many trees during the 1960’s, 70’s and 80’s. To secure the supply of orange juice for the US market, trees were planted and large processing plants were built for orange concentrate in Brazil. The first concentrate plant was built in Brazil in the early 1960’s and the large expansion in production capacity took place during the 70’s and 80’s. Orange processing in Brazil was established by US companies.
1.2.2 ORANGE CROP DISEASES
Like any other fruit, orange trees are susceptible to diseases. These may affect the leaves or fruit and even kill the trees. Because diseases have a large economical impact on the citrus industry, many orange-growing regions allocate large funds for research on citrus diseases, and develop more resistant fruit cultivars and cultivation methods to limit their effects.
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1.3 Bridging the seasons
The characteristics of a disease will determine the appropriate response to control it. Control methods include the eradication of infected trees, chemical suppression of disease-transmitting insects and using resistant rootstock for grafting. New trees should come from controlled nurseries where seedlings are protected from airborne or soil contamination. The inspection of groves and follow-up of measures taken are important for successful control of a disease. Large eradication programmes may require special funding. In the 1940’s almost all orange trees in Brazil were destroyed following an outbreak of CTV (Citrus Tristeza Virus). New plantings were made using a different rootstock (Rangpur Lime) resistant to this virus. Among the serious citrus diseases found today is Citrus Canker, caused by Xanthomonas bacteria, that results in premature leaf and fruit drop. There is no treatment but the disease is limited by removing all trees within a 60 m radius of infected trees. CVC (Citrus Cholorosis Variegated), caused by a bacterial pathogen transmitted by the sharpshooter insect, leads to spotted leaves and small fruit. The fungal disease Citrus Black Spot causes lesions on the fruit skin, which make fruit unsuitable for consumption although it can still be processed. In 1999, a new disease was discovered in Brazil called Citrus Sudden Death (CSD) because it caused the rapid decline and death of trees with fruit and leaves still on them. It is caused by an insect-transmitted virus (similar to Tristeza) and in just a few years it has spread to important citrus areas of São Paulo State. Certain rootstocks are resistant to the Sudden Death virus. Now there is intensive replanting using resistant trees as well as in-arching, where resistant seedlings are planted next to an existing exposed tree and a by-pass is grafted onto it above the bud union. However, since these alternative rootstocks are less resistant to drought, they may require more irrigation or be used to plant groves in areas having a wetter climate.
Fig. 1.4 Harvesting seasons in Brazil and Florida.
1.3 Bridging the seasons Oranges can only ripen on the tree and the quality of the fruit begins to deteriorate immediately after picking. Therefore, the time between picking fruit and processing it into juice and other products should ideally be as short as possible – less than 24 hours – although longer periods are not uncommon. Because the orange is a seasonal fruit, each region strives to grow orange varieties with different ripening periods (see Figure 1.4). This prolongs the total harvesting period in a region and allows greater utilisation of processing equipment. To provide a year-round supply to consumers, juice must be stored to bridge the gap between seasons. Most of the juice is stored frozen as concentrate. This is called Frozen Concentrated Orange Juice, or just FCOJ as it is referred to within the industry. For the same amount of ready-to-drink (RTD) juice, concentrate requires 5–6 times less volume for storage and shipping than singlestrength juice. Thus shipping costs over long distances are significantly higher for single-strength products like not-from-concentrate juice (NFC).
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1.4 Fruit selection
Juices from early and late fruit varieties differ in quality as regards colour, sugar content, etc. To deliver products of specified and consistent quality throughout the year, concentrate suppliers blend concentrates produced from different orange varieties. Most NFC products also consist of a blend of juices extracted at different times of the season. Blending of NFC may take place within the producing country or in the importing market. The difference in quality and yield between different orange varieties is reflected in the range of market prices.
In plants where NFC is produced, concentrate should also be produced to make use of the “nonoptimal” fruit. In most regions, fruit best suited to NFC production is available for only part of the season. The proportion of NFC and concentrate produced in a certain region will depend on the availability of suitable fruit. At present, NFC production makes up a low percentage (<10 %) of the total juice production in most orange-growing regions except for Florida, where the share of NFC production can reach 45 %. With oranges grown to be eaten fresh, a certain amount of fruit is rejected because of poor appearance (up to 20 %). The rejected fruit is used for processing into juice. This is why juice processing facilities are also found in regions which specialise in producing oranges intended for the fresh fruit market.
1.4 Fruit selection In Brazil, the typical processing season is from June to February. In Florida, oranges are usually processed from late October to early June. Good quality fruit is harvested for the greater part of the season. In the Mediterranean, the period yielding fruit of quality suitable for processing is shorter than in Florida and Brazil. NFC is essentially juice as it is extracted directly from the fruit. Regulations and the production process allow for very limited, if any, adjustments to product characteristics other than blending NFC from different varieties. Therefore careful selection of the fruit is necessary for NFC production. In concentrate production it is possible to adjust certain quality parameters. Careful control of the evaporation step, essence recovery and the possibility of blending concentrates that differ in character enable the processor to meet many different product specifications. Hence, variations in fruit properties are less critical for concentrate production.
1.5 Inside an orange Essentially, an orange is a ball of juice sacs protected by a waxy skin, the peel. The peel consists of a thin outer layer called the flavedo and a thicker, fibrous inner layer called the albedo. Orange-coloured substances called carotenoids in the flavedo give the fruit its characteristic colour. Vesicles (a small sac or cavity) containing peel oil also present in the flavedo contribute to the fruit’s fresh aroma. The white spongy albedo contains several substances which influence juice quality, often negatively, if they find their way into extracted juice. These substances include flavonoids, d-limonene, limonin and pectin.
ABBREVIATIONS AND DEFINITIONS FCOJ = Frozen concentrated orange juice NFC = Not-from-concentrate juice Single strength = The natural strength of juice and that at which it is consumed. Single-strength equivalent (SSE) = Concentrate and other products stated as their corresponding amount of single-strength juice.
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1.6 Squeezing out every drop
1.6 Squeezing out every drop
Central core Flavedo
Juice vesicles
In theory, the aim of the juice extraction process is to remove the maximum amount of juice from the fruit without including any peel. In practice, a compromise is made between the possible juice yield and the desired product quality. The maximum juice yield from an orange is 40–60 % by weight depending on the fruit variety and local climate. Valuable oil from the peel is recovered during juice extraction. Volatile flavours from the juice are also recovered during juice processing. The remaining material is mainly pulp, peel, rag and seeds. Some pulp is recovered for sale as a commercial product. Soluble solids are reclaimed from the remaining pulp stream by washing with water. d-Limonene is extracted from oil in waste peel for use in the chemical and electronics industry. Other by-products such as pectin and clouding agents are sometimes recovered. Peel and other residual waste can be dewatered and dried as pellets for animal feed. Because orange waste is very biodegradable, small plants may dispose of it as landfill. Increased cost-efficiency is important for the orange juice industry. The development of equipment within the citrus processing industry is aimed at increasing juice yields while maintaining juice quality. It is also very important to reduce energy costs and to further refine by-products and find new uses for them.
Albedo Oil sacs
Seed Segment
Segment wall
Fig. 1.5 The structure of an orange.
The edible portion of the fruit is known as the endocarp. It consists of a central fibrous core, individual segments, segments walls and an outer membrane. The segments contain juice vesicles, or juice sacs, that are held together by a waxy substance. Seeds may also be present within the segments. (See Figure 1.5.) Apart from the juice itself, droplets of juice oil and lipid are also present in the juice vesicles. The juice contains sugars, acids, vitamins, minerals, pectins and coloured components along with many other components. These are discussed in more detail in subsection 2.2. After juice is extracted, pieces of ruptured juice sacs and segment walls are recovered as pulp. When these particles are large, they are referred to as floating pulp because they rise to the surface of the juice. Very fine particles and suspended solids that gradually accumulate at the bottom of the juice are called sinking pulp.
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1.7 Primary and secondary products
1.7 Primary and secondary products
Juice
This product is produced either: • as a single-strength (natural strength) bulk product in frozen or aseptic form (NFC); • as bulk concentrate normally frozen (FCOJ).
The orange is one of nature’s gifts. The two primary products – whole fruit and juice – are enjoyed worldwide. Various secondary products, the by-products, help to maximise profits and minimise waste. No part of the fruit is unused after the juice is extracted if fruit throughput justifies investment in equipment needed to turn pulp and peel into commercial products. A range of products that can be obtained from oranges is summarised below, many of which are discussed in greater detail in other sections of this book. Yields of the various products derived from Florida Valencia oranges are shown in Figure 1.6.
Comminuted citrus base
A by-product made either by milling the whole fresh fruit or by mixing juice concentrate with milled peel. This product is used as an ingredient for fruit drinks. Because comminuted citrus base has a stronger flavour and provides more cloud than pure orange juice, it imparts a good orange flavour to fruit drinks of low fruit content. It was originally developed in the UK. Pulp
This is ruptured juice sacs and segment walls recovered after the extraction process. It can be added back to juice and juice drinks to provide mouthfeel and give a natural appearance to the product. Pulp, also traded as “cells”, is usually distributed frozen but also in aseptic bag-in-box containers.
Fresh fruit
After picking, fruit intended for the fresh fruit market is sent to packing stations where it is normally graded by visual inspection, washed, coated with wax and packed. The detergent used in washing may include fungicides. As traces of fungicide could find its way into juice, fruit from packing houses may not be processed into juice for sale to, for example, the European Union countries.
1000 kg
553 kg Essence oil: 0.1 kg
Juice
Essence aroma: 1.1 kg
Pulp: 30 kg
65 °Brix concentrate: 100 kg
Peel oil: 3 kg
Evaporated water: 452 kg
Peel, rag and seeds: 413 kg
Fig. 1.6 Products derived from whole Florida Valencia oranges. Source: SunBase, Florida
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1.7 Primary and secondary products
Pulp wash
d-Limonene
A product reclaimed from washing the pulp stream. Pulp wash contains soluble fruit solids and is often used in fruit drink formulations as a source of sugars and fruit solids. It is also used as a clouding agent to provide body and mouthfeel because of its pectin content. If the law permits, pulp wash is sometimes added to juice in-line before concentration. Pulp wash is also referred to as water-extracted soluble orange solids, WESOS.
The major component of peel oil. Industrial d-limonene is recovered as a by-product from waste peel in the feed mill. It is sold for use in the plastics industry as a raw material for the manufacture of synthetic resins and adhesives. It has also found use as a solvent, e.g. in the electronics industry. Animal feed
Dry pellets made from the material left over from juice processing. The waste stream consists of peel, rag, unrecovered pulp and seeds. This residue is dewatered and dried to form concentrated fodder for cattle and sheep.
Peel oil (cold-pressed oil)
The oil extracted from orange peel. Some peel oil is added to concentrate after evaporation prior to long-term storage. It masks or slows down the development of a cardboard off-taste during storage. Peel oil is sometimes used by blending houses and juice packers for extra additions to concentrate. It is sold to flavour manufacturers for the production of various flavour compounds used in the beverage, cosmetics and chemical industries. In trading, it is often referred to as CPO, cold-pressed oil, or CPPO, cold-pressed peel oil.
Citrus molasses
The syrup produced from the concentration of liquor pressed from the wet waste stream. It is used in producing animal feed pellets or as raw material for the production of citrus alcohol by fermentation. Pectin
A less common by-product of fruit peel. Pectin can be extracted from the peel for use in jam, marmalade, jelly and preserve production.
Essence
Essence comprises the volatile components recovered from the evaporation process. These are separated in an aqueous phase and an oil phase. The water-soluble compounds (essence aroma) are sometimes added back to the concentrate or juice product. The oil phase (essence oil) is different from peel oil and contains more of the fruit flavour. Essence oil is also used as add-back to concentrate. Both aroma and essence oil are raw materials used by flavour companies for the manufacture of flavour mixtures for the beverage and other food industries.
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1.8 Major orange-producing regions
Mexico 1.7 % Cuba 1.3 % Greece 1.2 % South Africa 0.9 % Australia 1.1 % Egypt 0.4 % Others 1.7 %
1.8 Major orange-producing regions Together, Brazil and the USA grow 50 % of the world’s oranges and produce more than 85 % of the global orange juice supply (12 billion litres/year). Regions contributing to the majority of world orange juice production are shown in Figure 1.7. The export of orange juice onto the world market is dominated by Brazil. US exports are quite small as a consequence of the large domestic market for orange juice. (See Figure 1.8). The USA has been a significant net importer of juice. However, as juice production in Florida increased as a result of new tree planting, US net juice imports have gradually declined to a low level, the quantities depending on the size of the Florida harvest. Thus more juice available on the world market must find new or existing markets. Figure 1.9 shows the orange juice production in Brazil and Florida between 1996-2003.
Spain 2 % Italy 3 %
Brazil 51 % USA 36 %
Fig. 1.7 World orange juice production, 2001/02. Source: FAO
1.8.1 BRAZIL
During the 2002/03 season, the orange crop in Brazil was about 15 million tonnes (370 million boxes of 40.8 kg/90 lb). Almost all commercial groves and processing plants are located in the state of São Paulo, where 280 million boxes were produced. The 2002/03 harvest saw a 25 % lower fruit yield than the previous and following harvests, following cyclic fluctuations in yield.
The majority of Brazilian oranges goes into processing. Nevertheless, the domestic fresh fruit market, selling for home-squeezed orange juice, makes up a significant share of the total production resulting from the increase in per capita income.
1800 1600
Thousand tonnes
1400 1200 1000 800 Others Belize Costa Rica Spain USA
600
Brazil
400 200 0 86
88
90
92
94
96
98
Year
Fig. 1.8 World export of frozen concentrated orange juice (FCOJ), NFC volumes calculated as concentrate. Source: FAO
10
00
1.8 Major orange-producing regions
10,000
Million litres
8,000
Brazil
6,000 4,000
Florida
2,000 0 96/97
97/98
98/99
00/01
99/00
01/02
02/03
Fig. 1.9 Orange juice production in Brazil and Florida as SSE, single-strength equivalents. Source: Florida Department of Citrus
Sweet oranges comprise the bulk of the Brazilian crop. The most important varieties are: Pera Rio Pera Natal Valencia
(June to mid-July; mid-August to mid-December) (September to mid-January) (mid-July to September;midOctober to January)
Brazilian fruit tends to be smaller, less round and to have a thicker peel than oranges grown for processing in, for example, Florida. The normal processing season for Brazilian juice plants is from late June through to early February.
Boxes/tree
2.50 2.25 2.00 1.75 1.50 96/97
97/98
98/99
99/00
00/01
01/02
02/03
Crop year
Fig. 1.10 Average orange yield per tree in São Paulo expressed as boxes of 40.8 kg (90 lb)/tree. Source: USDA Gain report Brazil
11
Groves are not normally irrigated and climatic variations, including drought, can have a strong influence on fruit yield and juice quality. Some citrus varieties (Hamlin and Valencia) have a biennial cycle which leads to cyclic fluctuations in orange output. The variation in yield per tree obtained during recent harvest seasons is shown in Figure 1.10. In Brazil, the “bloom” – the time when the tree flowers and becomes pollinated before the new crop of fruit starts to grow – does not occur at the same time for all the trees in a grove or plantation. As a consequence, trees in a grove bear fruit of differing ripeness at any given time. Since fruit in a specific grove is gathered at one picking, the harvested crop will therefore vary in maturity. This variation in fruit ripeness forces the processor to make compromises in the juice extraction process that affect both the quality and yield of juice produced. Nevertheless, the processor can modify process conditions and use essence recovery and juice blending to compensate for variations in fruit to produce juice concentrate of consistent uniformity. Most juice in Brazil is processed into concentrate that is exported in large volumes. There is a small but growing production of NFC. This is intended for the South American market, as well as overseas export to North America and Europe.
1.8 Major orange-producing regions
Florida also produces about 40 % of the world’s grapefruit, of which 40 % is sold as fresh fruit and 60 % is processed into juices and fruit products. The Florida orange juice processing season extends from late October to late May/early June. Seasonal variations occur from year to year depending on the weather. Climatic conditions in Florida are such that the bloom occurs uniformly and during a very short period of time, usually two or three weeks. The high level of grove management includes irrigation and intensive pest and weed control. This combination of favourable climate and proficient grove management enables the fruit to ripen uniformly for efficient harvesting. Moreover, the uniform fruit quality enables the processor to select the optimum processing conditions for the fruit harvested each day.
1.8.2 FLORIDA
During the 2002/03 season, the orange crop in Florida was about 8 million tonnes (200 million boxes). This was a smaller yield, 15 % lower, than average for the early 2000’s. More than 95 % of the orange crop harvested in Florida is processed into juice or juice products. A combination of climatic conditions, tree variety and soil conditions results in fruit that has a low appeal to the fresh fruit market, but produces a very high quality of juice. The skin is not uniform in colour and it is often quite green or yellow. The peel is fairly difficult to remove, which contributes to consumer rejection. However, the round shape and thin peel of Florida oranges make them ideal for mechanical extraction systems. The main varieties of sweet oranges are: Early season Hamlin (October to January) Parson Brown (October to January) Mid-season Pineapple (December to March) Late season Valencia (February to June)
round shape and thin “The peel of Florida oranges make them ideal for mechanical dejuicing systems
”
During the early part of the season the orange juice is light in colour and has a low oil content, whereas during late season the juice has a stronger colour and higher oil content. Some mandarin and hybrid fruit is also processed into juice from December to April for blending in small amounts with orange juice to obtain the desired colour and/or flavour.
There has been a shift in processing oranges away from FCOJ to NFC to meet the demand of the North American market. At present, 35–45 % of the total orange crop goes to NFC production. In years with lower orange yields, processing to NFC is favoured while FCOJ production is reduced. Most NFC juice is consumed in the US. There are relatively short distances between juice production and consumption.
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1.9 Other regions
1.9 Other regions
Caribbean and Central America
This region includes several areas of small but increasing orange cultivation and orange juice production. Valencia is the most common variety of sweet orange. Grove management is not intensive and irrigation is rare. Climatic variations lead to differences in crop yield and juice quality between seasons. The main product in this region is frozen concentrate, although NFC is also produced for export markets. The orange processing capacity has been consolidated in Belize and Costa Rica, whereas capacity has expanded in Cuba, the largest producer in the region. Cuba’s citrus production increased steadily in the 1990’s. However, in 2001 a hurricane damaged a large part of the citrus-growing area. Cuba’s orange production in the 2001/02 season was 0.4 million tonnes, of which more than half went to processing. Cuba is among the world’s most important grapefruit producers, but output was dramatically reduced by the hurricane. Valencia oranges are harvested from December to June. Fruit harvested from March onwards tends to be high in sugar and low in acidity, which leads to very high Brix:acid ratios (>25). This juice therefore requires blending.
California
California is the second largest orange-producing area in the US as regards quantity of fruit, but is the leading supplier of oranges to the fresh fruit market. The dry climate results in oranges with thick skin and good appearance that appeal to consumers. The state produced about 2 million tonnes of oranges during the 2001/02 season. The dominant sweet orange variety in California is Navel, a seedless variety, followed by Valencia. Both are grown primarily for the fresh fruit market. About 20 % of the crop, which for some reason is considered unattractive to consumers, is used for fruit processing. Navel orange juice has the peculiarity of developing a bitter taste after processing. In small amounts, Navel juice can be used for blending with other juices or, alternatively, the bitterness can be removed in a debittering process. Other orange-growing states in the USA are Arizona and Texas. Mexico
During the 2000/01 season, 3.8 million tonnes of oranges were produced in Mexico. Oranges make up two thirds of citrus production, limes come second with nearly 30 % of total production and their plantation area is increasing. The sweet orange crop is dominated by the Valencia variety, and most of the fruit (about 85 %) goes to the fresh fruit market. The majority of groves are small, a result of Mexican land reform and regulation that limit the size of farms. In the orange-growing areas there is often a shortage of investment money and difficulty in achieving effective grove management. This leads to variations in crop size and fruit quality from year to year. The production quantity of FCOJ depends on world market prices for FCOJ and raw material costs. In years with short orange supply, prices are high in the domestic fresh fruit market and so less fruit goes to processing.
Argentina
Citrus production in Argentina was about 2.3 million tonnes in 2003. Oranges made up about 30 % of the total crop, the main outlet being the fresh fruit market. However, lemon is the most important citrus crop, with Argentina being the world’s largest producer of lemons, yielding about 1 million tonnes annually. Most lemons are grown in the northeast province of Tucuman. One third is exported as fresh fruit, whereas about two thirds are processed into lemon juice. Local consumption of lemons is small, and the main markets for lemon export lie in the Northern Hemisphere. Fresh fruit export to some regions has been constrained by the required protocols and phytosanitary standards, but these demands are now being increasingly met.
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1.9 Other regions
China
Japan
China has the highest growth in citrus fruit production, with the provinces Sichuan, Guangdong and Zheijang accounting for the largest yields. In 2001, the seasonal production was about 12 million tonnes, up 50 % in 5 years, and extensive citrus tree planting is expected to further increase harvests. Nevertheless, compared with other large citrus-producing regions, fruit yields are relatively low because of poor cultivar availability and grove practices. Mandarins account for more than half of citrus harvests in China, although the trend is to reduce mandarin planting in favour of sweet orange cultivars. These include Hamlin, Valencia and Chinese varieties, which make up about 30 % of the total citrus production. Most oranges are consumed fresh with very little being processed into juice; the predominant processed product is canned mandarin. At present, the majority of oranges are harvested during a short period. Since fruit quality deteriorates rapidly after harvesting, there is only a short fresh fruit consumption period of 3–4 months. In comparison, Brazil and Florida have typical harvesting cycles with balanced yields over 7 months. Therefore there is a strong desire in China to change to fruit varieties that result in longer consumption and processing periods. The per capita growth in income has led to the rapidly increased demand for orange juice, especially in large cities. But until greater orange production can support efficient processing, this demand will continue to be satisfied by juice imports over the next few years. Likewise, it will be difficult to meet the demand for fresh fruit by domestic production in the foreseeable future, especially as the per capita fresh citrus consumption is expected to increase by 50 % over the next 10 years. Fresh fruit will continue to be the main market for domestic oranges. When China joined the WTO in 2001 it agreed to reduce tariff rates, a measure that promotes higher imports of fresh fruit and orange juice.
Citrus fruit grown in Japan consists primarily of mandarin varieties, some of which are processed into juice. However, since the strict restrictions governing fruit juice imports into Japan were lifted at the end of the 1980’s, production of mandarin juice has decreased to a low level. Imported orange juice concentrate now meets the needs of the rapidly expanding domestic juice market. Japan is also a large importer of fresh grapefruit and orange fruit, mainly from the US. Periods of economic downturn also show in declining imports. Australia
Sweet orange varieties in Australia are Navel and Valencia. Because of the high popularity of Navel – it is easy to peel and enjoyable to eat – and new plantings replacing old Valencia trees, it now accounts for about half of the crop and supplies the fresh fruit market. The orange production in Australia was about 0.6 million tonnes for the 2001/02 season, a high-yield year in the biennial yield cycle. Fruit for processing, mainly Valencia, typically accounts for 40 % of the total harvest. The Australian market for NFC has increased rapidly over the last few years and domestic producers are shifting from FCOJ to NFC production, which offers higher profitability. It is difficult for Australian producers to compete at world market prices for concentrate in the domestic market. Frozen concentrate now accounts for half of the juice market, mainly imported from Brazil. There is also a drive to increase the export of fresh fruit, primarily Navel, to Far East markets and increasingly to the US. As Australia has an alternate season to the US, it can supply the US market with high-quality fruit during the California Navel off-season.
14
1.9 Other regions
Oranges in the Mediterranean region are primarily grown for the fresh fruit market, both domestic and for export to European countries. About 15 % of regional crops goes into processing. The Mediterranean is also important for other citrus fruits. Mandarin production is about 4.5 million tonnes, or 30 % of world production. Lemons, about 3 million tonnes, account for 30 % of world supply. Spain is the largest Mediterranean producer of oranges and mandarins, the most important sweet orange varieties being Navel and Valencia. Exports to fresh fruit markets dominate. Production of orange concentrate has been reduced drastically in Spain because production costs are not competitive with world-market concentrate prices. This is despite the fact that processors in European Union countries are entitled to a significant subsidy for purchasing fruit for juice production. NFC is produced for the European market from high-quality Valencia fruit but volumes are limited by fruit availability.
Million tonnes/year
0
2
4
6
8
10
12
China Spain Mexico India Italy Iran Argentina Egypt Pakistan Turkey Japan South Africa
Spain is the largest “Mediterranean producer of
Morocco Greece
oranges and mandarins
”
Cuba Production Processing
Australia
The cultivation of seedless clementines in Spain has met with success and is much appreciated by consumers. Most fruit is exported and accounts for 50 % of world mandarin exports. In Italy, orange concentrate production has also dropped drastically because of strong international competition as regards price. However, several types of blood orange unique to Sicily are grown on the island. Juice from these oranges has created a niche market for export of both NFC and concentrate. In other cultivation areas, replacement of blonde oranges with more profitable pink grapefruit is taking place.
Israel
Fig. 1.11 World citrus fruit production and processing except Brazil and Florida, 2001/02. Source: FAO
Mediterranean countries
In order of crop size, the most important orangegrowing countries in the Mediterranean are Spain, Italy, Egypt, Turkey, Greece, Morocco, Syria, Algeria and Israel. About 11 million tonnes of oranges are grown in this region (2001). This represents about 20 % of world orange production, and slightly more than the current yield in Florida.
15
1.9 Other regions
Citrus production in Israel has been declining for many years. Orange production was less than 0.2 million tonnes in 2002, similar to grapefruit production. The drop in concentrate production has caused the closure of processing plants. Uprooting of orchards is carried out because of low profitability, urbanisation and an increasing water shortage. The main varieties of sweet oranges grown in Israel are Shamouti (early) and Valencia. (Jaffa is not a fruit variety but a trade name used for fruit and juice exported from Haifa harbour.) The CMBI (Citrus Marketing Board of Israel), which encouraged the production and marketing of citrus for more than 65 years and actively built up the European juice market, closed in 2003.
South Africa
South Africa has an expanding citrus industry, the main orange varieties being Valencia and Navel. Most of the orange production, some 1.3 million tonnes, is exported as fresh fruit. About 20 % goes to the domestic fresh fruit market and the same amount is processed into concentrate. Traditionally, the main export market for orange fruit was Europe, but deregulation in 1997 opened up new opportunities that led to Japan and the Middle East becoming important markets. South Africa has good potential for exporting fresh fruit to the northern hemisphere because of its alternate season. However, increased trade depends on South Africa meeting the phytosanitary requirements and production protocols of the importing regions. Changes in the organisation of the South Africa citrus industry have taken place aimed at enabling producers to meet importers’ demands more efficiently.
16
2
Orange juice quality and categories
In section 2 you will read about: • How quality is assessed in objective and subjective ways. • Substances and factors that are important to juice quality, such as sugars and acids, cloud, pulp, flavour and colour components, and vitamin C.
• How the different quality parameters are measured. • Orange juice categories and the terms used to describe the various types of orange juice. • An introduction to regulations governing juice quality.
17
2. Orange juice quality and categories Juice categories and relevant terms Many special terms are used for the two main categories of orange juice products, ready-to-drink orange juice and juice concentrate. Some of these terms are referred to in the regulations of certain countries, other terms are merely used in juice marketing and trading. Standards and regulations governing product origin, juice processing, juice quality and product labelling are implemented by a number of regulatory bodies in different trading blocs. There is a general desire worldwide to harmonise the standards in force.
Summary The most important compounds that influence the quality of orange juice are sugars and acids, flavour and colour components, and vitamin C. These compounds, plus cloud, are analysed to define and grade juice. The °Brix scale is used to measure sugar concentration, and juice acidity is measured by titration. There are several methods for measuring cloud and colour. Flavour is evaluated using subjective methods and is thus difficult to define and measure. The deterioration of juice quality is mainly related to flavour degradation, nonenzymatic browning and nutrient loss. Enzyme activity affects the mouthfeel of juice, and the formation of limonin makes juice taste bitter.
2.1 Juice quality 2.1.1 DEFINING QUALITY
For food products, quality is subjective and what is good quality must ultimately be determined by the consumer. This is also true for orange juice. The quality of orange juice as perceived by the consumer is made up of: • taste • mouthfeel • colour
TABLE 2.1 IMPORTANT QUALITY PARAMETERS FOR ORANGE JUICE Sugar content (°Brix) Acid content Ratio of °Brix to acid Cloud Pulp
However, because orange juice is traded and consumed worldwide, its quality cannot be determined solely by subjective assessments. To make assessments more objective, several quality parameters have been defined. Some of these parameters are used to classify (grade) orange juice, while others are used to specify the product for trading. Table 2.1 lists the important quality parameters for orange juice.
Flavour Oil content Colour Vitamin C Defects
All the parameters listed in Table 2.1, except flavour, can be determined by standard methods of analysis to give meaningful and reliable results. Orange juice flavour can only be evaluated by sensory means, usually by groups of panellists. These analysis methods have been collected and published in books by, for example, Redd et al. and Kimball.
18
2.1 Juice quality
All processing and storage of juice on its way to the consumer should aim at maintaining the initial quality as much as possible. Equally important is the quality of water used to reconstitute orange juice, as juice made from concentrate comprises 85 % added water. The effects of processing on quality are mainly related to flavour degradation, while nonoptimal storage conditions can result in juice browning, loss of vitamin C and flavour changes.
TABLE 2.2 AIJN QUALITY REQUIREMENTS FOR ORANGE JUICE Properties Relative density 20/20 Corresponding °Brix
Direct juice min. 1.040 min.10
Properties L-ascorbic acid (vit. C) at end of shelf life, mg/l Volatile oils, ml/l Hydroxymethylfurfural (HMF), mg/l Volatile acid as acetic acid, g/l* Ethanol, g/l D/L Lactic acid, g/l Arsenic and heavy metals, mg/l
Reconstituted juice min. 1.045 min. 11.2
Direct juice / Reconstituted juice min. 200 max. 0.3 max. 10
2.1.2 QUALITY SPECIFICATIONS
Guidelines for quality standards for fruit juices for the European Union are specified in the Code of Practice for the evaluation of fruit and vegetable juices, published by the AIJN (see Section 11). The absolute quality requirements defined in the reference guideline for orange juice are given in Table 2.2. In the USA, the US Department of Agriculture, USDA, is responsible for specifying quality standards for orange juice. To be labelled USDA Grade A, orange juice produced in Flor ida must meet the quality requirements shown in Table 2.3. The quality factors are measured on a 100point scale. If the total score is above the limit but just one of the quality factors does not meet the Grade A requirements, the juice still may not be labelled Grade A. The most important properties of orange juice that are directly related to these quality parameters are discussed in the following subsections.
max. 0.4 max. 3.0 max. 0.2 max 0.01–5.0 (various values)
* Indication of hygiene, not juice acidity. Source: AIJN Code of Practice, Reference guideline for orange juice, 2003
The basic quality of orange juice is determined at the fruit processor, i.e. by the quality of fruit accepted at the reception area, fruit storage times and the way juice is extracted. Subsequent processing steps cannot improve the main quality parameters of a given production batch. This can only be achieved by blending a particular juice with superior quality orange juice or concentrate. This is commonly done.
TABLE 2.3 REQUIREMENTS FOR USDA GRADE A ORANGE JUICE Orange juice Analytical factors °Brix Ratio (Brix:acid) Recoverable oil % v/v.
NFC
From concentrate
min. 11.0 12.5 – 20.5 max. 0.035
min. 11.8 12.5 – 20.5 max. 0.035
Quality factors Appearance Reconstitution Colour Flavour Defects Total score
fresh orange juice —— very good, min. 36 points very good, min. 36 points practically free, min. 18 points min. 90 points
fresh orange juice reconstitutes properly very good, min. 36 points very good, min. 36 points practically free, min. 18 points min. 90 points
Source: USDA
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2.2 Important properties of orange juice
2.2 Important properties of orange juice
HOW BRIX IS MEASURED Brix can be measured by either density measurements or by measuring the refractive index of orange juice. Both are then related to a 100 % sucrose solution. The °Brix scale is based on standard measurements at 20 °C. If the juice/ concentrate is analysed at any other temperature, a correction factor is used to equate the °Brix measurement to one made at 20 °C. To obtain the corrected °Brix value, the acid content must be determined by titration in order to read the right correction value from a table.
2.2.1 SUGARS AND ACIDS
The most important properties of orange juice are its sugar content and ratio of sugar to acid content. This ratio indicates the balance between sweetness and acidity in the juice. When the fruit matures, this ratio increases as sugars are formed and the acid content decreases. The sugars are mainly sucrose, glucose and fructose in a ratio approximating to 2:1:1. The sugar content of juice is normally expressed as °Brix. In extracted juice, the concentration of sugar typically varies from 9 °Brix for early season varieties to 12 °Brix for fruit harvested late in the season (e.g. Florida). The °Brix (degree Brix) scale, which was developed by the sugar industry, relates the sucrose concentration of a pure sucrose solution to its density at 20 °C. °Brix for orange juice not only includes the concentration of dissolved sugars but all soluble solids. Dissolved substances other than sugars will influence the result of °Brix measurements. Thus, the level of acid, the second most abundant dissolved material, is often measured and a correction of the Brix value is made. For single-strength orange juice, acid correction is small and the term °Brix is commonly used without correction to mean only the sugar content. However, in measuring °Brix of orange juice concentrate, the acid correction is important due to the much higher acid content of concentrate. Here, the term “°Brix, cor rected” is used.
Density measurements: The buoyancy of a hydrometer in a liquid is directly proportional to the density of the solution. Therefore a scale on the neck of the hydrometer can be calibrated to a °Brix scale. The °Brix is read on the scale at the point where the liquid meniscus intersects the hydrometer neck. Before measuring it is important to deaerate the juice since air in the sample can affect the result. Hydrometers are mostly used for singlestrength juice. Although a hydrometer is an inexpensive instrument, it is not very fast and requires up to 200 ml of sample. For in-line Brix measurements, one common method of measuring density is to feed the sample through an oscillating tube. When the liquid enters the tube, the frequency of the oscillations decrease. From this deviation the density can be calculated. Read more about inline density measurements in subsection 7.4.8. Measurement of light refraction: Light travels at different speeds in different media such as air, water or sugar solutions. When light passes from one medium to another it is refracted, that is, it changes direction slightly. This property of a medium can be quantified as its refractive index. The refractive index of a solution depends on its total soluble solids. Therefore °Brix can be determined by measuring the refraction of light. Either analogue or digital refractometers can be used to measure °Brix. Although refractometers are more expensive than hydrometers, they are more frequently used because they can measure over a large scale, 1–70 °Brix, and they constitute a fast method which requires very little sample, 2–3 ml. Modern refractometers can compensate for temperature, but independent correction for acids is necessary, especially for concentrates. Read more about in-line refractometer measurements in subsection 7.4.7.
°Brix = % soluble solids (w/w) °Brix, corrected = % sugar (w/w) In the laboratory, the °Brix of orange juice is analysed by measuring the juice density with a hydrometer or by measuring the refractive index of juice using a laboratory or hand refractometer. Two basic instruments used for Brix analysis are shown in Figure 2.1. Read more about in-line measurements in subsection 7.4.
Source: Dan A. Kimball, Citrus processing: Quality control and technology, 1991.
20
2.2 Important properties of orange juice
Density: – hydrometer
Light refraction: – hand refractometer
HOW ACIDITY (TOTAL ACIDS) IS MEASURED Juice acidity is measured using a chemical titration method. Orange juice contains acids which release hydrogen ions (H+) in solution. When a base which releases hydroxyl ions (OH ) is added to an acid media, a chemical reaction takes place which gradually turns the solution neutral.
Fig. 2.1 Examples of instruments used for °Brix measurements.
After sugars, acids are the most abundant class of soluble solids in orange juice. The acids comprise mainly citric acid and to a lesser degree malic acid. Some of the acids are in the form of salts, which give orange juice a buffering capacity. Thus even though the acid content may vary a lot, the pH of juice extracted from mature oranges is generally between 3.2 and 3.8. Total acid content (acidity) is measured by titration and is often expressed as grams citric acid per litre juice.
H+ + OH- ➞ H2O To analyse the acid content in a juice sample, a base (e.g. sodium hydroxide, NaOH) of known concentration is slowly added under agitation until a specific pH value is reached. Most official methods state that the end pH value should be 8.1 (AOAC*) – 8.2 (USDA). However, some producers titrate to pH 7.0 (neutral) and it is therefore important to mention the end pH together with the acid content. The change in pH can be detected by a pH electrode or by using a sensitive pH colour indicator that changes colour abruptly at pH 8.2. When the size of the juice sample, the concentration of the base and the amount of base added are known, the total concentration of acids in the juice can be calculated. In Europe, the acidity of orange juice is expressed as grams citric acid per litre juice, whereas in the USA it is expressed as grams citric acid per 100 grams juice, or % w/w.
Ratio
The Brix:acid ratio is very important for taste as it is a measure of the balance between the sweet and sour sensation. As oranges ripen, the acidity decreases while the sugars increase. Therefore the Brix:acid ratio will also increase. The ratio decides the maturity of the fruit before harvesting. Maturity standards for oranges in Florida require a minimum °Brix of 9.0 and a minimum Brix:acid ratio of 10. Consumers prefer a ratio around 15 and therefore it is often necessary to increase the ratio. In the USA, the only permitted way of doing this is by blending low-ratio juice with juice of higher ratio extracted at other times of the season. In the EU, sugar may be added up to 15 g/l orange juice for balancing acidity without having to label it “sweetened”. Many other countries also allow for small amounts of sugar addition but the permitted level may vary. Therefore local legislation should be consulted for details of this. Adding sugar to juice for sweetening purposes (in higher concentrations than above) is not permitted without highly visible information on the package indicating this. Removal of acid from the juice, deacidification, would also increase the ratio but is not permitted for orange juice in most countries. Orange juice concentrate can be bought with different ratios; typical values lie between 14 and 17.
EXAMPLE Procedure Pipette 10 ml of single-strength juice or weigh 5–10 g concentrate into a beaker. Pour sodium hydroxide (NaOH) of concentration 0.1562 N into a burette. The pH can be indicated by adding 5 drops of phenolphthalein or by using a pH meter. Titrate until a slight darkening in the juice persist or until pH 8,20. Read off the amount NaOH used from the burette. Calculation Single-strength juice: % acid = ml titration solution/10.4 Concentrate: % acid = ml titration solution/g concentrate * AOAC The association of official analytical chemists.
Ratio =
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°Brix % (w/w) citric acid
2.2 Important properties of orange juice
2.2.2 CLOUD AND PULP
Cloud in orange juice is considered a desirable characteristic; it gives an opaque appearance to the juice and is important for the mouthfeel. Orange juice cloud is formed by soluble and insoluble (suspended) compounds released during juice extraction. Pectin is an important soluble cloud constituent because it increases the viscosity of the juice liquid, thereby allowing solid particles to remain suspended. So-called “cloud loss” is caused by a loss in viscosity due to reactions between pectin molecules and calcium. In the reaction, long pectin molecule chains are formed which settle to the bottom. Cloud loss leads to total separation of suspended particles, leaving an upper clear phase and a lower cloudy phase consisting of solid matter settling towards the bottom. If the same reaction between pectin and calcium takes place in orange juice concentrate, it will instead lead to gelation of the concentrate. You can read more about this in subsection 4.4. Another important contributor to the opaque appearance of juice is the suspended solids also known as pulp. The very small pulp particles called “sinking pulp” are closely related to cloud. Some sedimentation of these particles will occur during storage. This sedimentation is not related to cloud loss. Pulp is made up mainly of ruptured fruit cell walls, segment walls and core fibre. Two kinds of pulp are found in juice:
HOW CLOUD AND PULP ARE MEASURED Sinking pulp Different procedures for measuring the pulp and concentration of suspended solids of orange juice are used by the industry, therefore it is often impossible to compare values from different sources. The juice sample is centrifuged in graduated tubes for a known time and speed. Solid material above a certain particle size will settle in the tubes according to the time and centrifugal force of the lab centrifuge. The recommended procedure in the juice industry is to spin the juice sample at 370 g for 10 minutes at 26 °C (USDA method), whereas the Tetra Pak method uses 3000 g for 3 minutes. The higher g-force used in the Tetra Pak method gives a more compact pulp sediment and therefore a significantly lower reading than the recommended method for juice of the same pulp content. The sedimented quantity is expressed as volume %. Not only may the time-speed combination vary greatly from method to method, but the results may be referred to suspended solids, suspended pulp, centrifugable pulp or sinking pulp. Floating pulp Floating pulp is often measured by a sieving method. Sieves with different hole sizes are used to determine the amount and size of pulp in juice. (See subsection 8.2) Cloud stability Cloud stability is detected by measuring the transmittance of orange juice in a spectrophotometer. This analysis method is based on the fact that both soluble and insoluble solids absorb light, with the result that only a certain amount of total light entering a sample will pass through it. The orange juice sample is centrifuged to take away larger suspended particles (sinking pulp). The light transmittance of the sample serum is measured at 650 nm wavelength. The denser the cloud in orange juice, the lower the transmittance, %T. Orange juice cloud is not considered stable if the %T at 650 nm is greater than 36.
Sinking pulp, comprising particulate fibres that gradually settle out with time. This type of pulp is found in all orange juices and is an important part of orange juice cloud. Typical values in single-strength juice range from 5 % to 12 %, although the results depend very much on the analysis method used.
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2.2 Important properties of orange juice
Floating pulp, or cells, consisting of larger solid matter. Most of this rises to the surface of juice after it has been stirred. Floating pulp is added to concentrate or reconstituted juice. Its typical concentration in single-strength juice, if added, is 5–30 g/l (sieving method).
The first two components have already been discussed. The following text deals with the volatile components of orange juice. ‘Volatile’ means that the compounds will vaporise from the juice at elevated temperatures. The lower the temperature at which the flavour component evaporates, the more volatile is the component. As the orange ripens the volatile components are created and increase. The volatiles are of two types – water-insoluble oils and watersoluble aromas. In everyday speech, volatile components are referred to as flavours. During the production of orange juice concentrate, most of the volatile flavours are removed in the evaporation step by being boiled off together with water. This results in juice concentrate having a flat cooked taste. However, the volatiles boiled off from juice are collected in an essence-recovery system. The orange flavour in the juice can later be restored by adding back the recovered fractions. Processing and storage of juice along the whole supply chain from tree to consumer are responsible for the changes in orange flavour caused by the juice losing or gaining components. Gained compounds are called off-flavours (not always volatile). They are of two kinds; • natural constituents of the fruit itself (from peel and rag) • compounds formed during processing and/or storage
More information on pulp and pulp production can be found in Sections 5 and 8.
Essence oil Peel oil
Essence aroma
Figure 2.2 The product streams that contain volatile flavours in a juice processing plant.
2.2.3 FLAVOUR
Flavour is the complex experience of the smell, taste and mouthfeel of a product. The flavour of orange juice is built up from a number of components, the most important of which are: • acids and sugars for taste • cloud for mouthfeel • volatile components for smell and taste
It is important to extract the juice so that unwanted compounds from peel and rag do not enter the juice. This is mainly achieved by avoiding too high a pressure in the juice extractors and juice finishers (see Section 5). Heat and oxygen are involved in the formation of off-flavour compounds during processing and storage. However, it is still not totally clear how the compounds that affect juice flavour are formed.
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2.2 Important properties of orange juice
There is no reliable instrumental method of determining orange juice flavour objectively, so it is carried out by sensory evaluation. As this is based on subjective judgement, the setup of sensory analyses for flavour and the evaluation of results are complicated. Nevertheless, flavour analyses must be carried out because of the importance of flavour as a quality parameter.
Volatile flavours
The volatile flavour components are found in three product fractions – peel oil, essence oil and essence aroma. To obtain good orange juice flavour, components from all three fractions must be present. However, the exact blend needed for an optimal orange juice flavour is still unknown. Peel oil. The recommended level of peel oil in reconstituted FCOJ is about 0.02 % v/v. When added to juice, peel oil gives body and freshness, although when used alone it can give an artificial taste. Oil levels much above 0.02 % v/v give rise to juice harshness and a burning taste.
Oil content
The oil content is often equated to d-limonene concentration since d-limonene is the dominant compound present in both peel oil and essence oil. d-Limonene acts as a carrier of flavours but contributes little to the flavour itself. However, excess of d-limonene can give a burning taste to juice. Juice processed under USDA directives may have a maximum oil content of 0.035 % v/v. However, consumer preferences range between 0.015 and 0.020 % v/v. High levels of oil in juice result from squeezing the fruit too hard when extracting the juice (for increased yield).
Essence oil. A typical concentration of singlestrength essence oil added to orange juice from concentrate is about 0.01 % v/v. When added to juice, essence oil gives top-notes and makes the juice fruity, green and sweet. Essence aroma. The essence aroma gives topnotes to the juice and makes it fresh and sweet. A typical concentration of single-strength aroma added to orange juice is about 0.2 % v/v. Addition of this fraction is more commonly found with premium quality juice products than with standard products.
HOW OIL CONTENT IS MEASURED The analysis of volatile flavours is often complicated and involves expensive instruments like a gas chromatograph. The d-limonene level can, however, be measured by a simpler titration method, the Scott method. Since it is not possible to titrate the juice directly, the oil must first be removed from the juice. This is done by heating up a mixture of juice and alcohol; the alcohol and oil evaporate readily from the mixture since they are the most volatile components. The alcohol and oil vapours are cooled down and collected. The d-limonene content in this mixture can then be determined by titration. The titration in the Scott method is based on a chemical reaction between d-limonene and bromide. A red colour indicator is first added to the sample and then a bromide solution is added slowly. Bromide reacts with d-limonene, and as long as there is d-limonene present in the sample the solution remains red. When the sample no longer contains any d-limonene the bromide reacts with the colour indicator instead and the red colour disappears. As the concentration of the bromide solution and the amount added to reach the colour change are known, it is possible to calculate the d-limonene content. The oil level is expressed as % v/v in 11.8 °Brix juice.
balance of flavour “Acompounds from peel oil, essence oil and aroma is essential for optimal orange flavour
”
The add-back of flavours to concentrate or reconstituted juice is carried out to different degrees. Most processors add essence oil, essence aroma and additional peel oil to develop a special taste. And today, dedicated flavour companies usually offer specially developed flavour packages to enhance a certain desirable flavour profile. Further details on volatile flavour fractions can be found in Section 8.
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2.2 Important properties of orange juice
In juice used for concentrate production, high oil levels are not regarded as a serious problem since most of the oil is boiled off in the evaporator. However, high oil levels in juice from the extractors may indicate that other unwanted compounds have entered the juice. These nonvolatile flavour compounds do not leave the juice during concentration. For NFC production, low-pressure extraction and/or downstream deoiling of extracted juice is often used to reduce the oil content to near 0.020 % v/v.
2.2.4 COLOUR
The intense colour of orange juice is mainly due to compounds called carotenoids. Colour, which should be bright yellow to orange-red and not too pale, is an important quality parameter. The fact that the USDA regards colour scores and flavour scores as equally important for orange juice shows the significance of colour.
HOW COLOUR IS MEASURED Colour is an important quality parameter but it is difficult to define and measure. The main methods used to evaluate colour are presented below.
Bitterness
Orange juice should have no noticeable trace of bitterness. Although even very small amounts of bitter substances are detectable by the consumer, bitterness is not a common problem for orange varieties normally used for processing. Some orange varieties mainly intended for the fresh fruit market such as Navel and Shamouti contain a precursor (a chemical substance that gives rise to another more important substance) of a very bitter compound called limonin. The precursor itself is not bitter, which explains why fresh fruit and freshly extracted juice of these varieties do not taste bitter. But when the juice sacs are ruptured during extraction, the limonin precursor enters juice where it is rapidly converted to limonin. A debittering process involving ultrafiltration and adsorbing separated bitter components on to resin can be used to remove the bitter taste. For more information see Braddock, 1999.
Known colour standards An example of this subjective method is the set of USDA colour tubes. One merely matches the colour of the orange juice sample with one of six colour standards in glass tubes. The comparison should be done under a defined light intensity around 150 candela. Colorimetry A colorimeter emits a flash of light from a pulsed xenon arc lamp to illuminate a juice sample and then measures the reflected light. The measured colour is then expressed according to the L, a and b scale. The L axis indicates lightness of colour, the a axis indicates the colour range from red to green, and the b axis indicates the colour range from yellow to blue. Although colorimetric measurements are not subjective, meaningful interpretation of results can only be made after fairly long experience. The colorimeter can also be calibrated to known standard colour tubes to make the colour measurements easier. Spectrophotometry The colour change that may occur in orange juice during storage is often called browning and is measured with a spectrophotometer. All cloud material is removed from the juice sample and the light absorbed by clear juice is measured at 420 nm wavelength. A wavelength of 420 nm is selected because the more red-brown the sample is, the more light will be absorbed at this wavelength. The higher the absorption, the more accurate the results.
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2.2 Important properties of orange juice
In dry and cooler climates such as in the Mediterranean, the colour of juice is well developed, while in hotter and more humid climates like that of Florida the pigments are diluted and thus juice has less colour. The only legal way to enhance colour is to blend the juice in question with another orange juice with a higher colour score (e.g. from Valencia oranges). In the USA it is also allowed to add up to 10 % tangerine juice to early season orange juice. Tangerine juice contains more carotenoids and therefore has stronger colour than most other citrus varieties. Colour can be measured by comparing the juice with known colour standards in glass tubes, or by using a colorimeter. Off-colours result primarily from formation of brown compounds that dull the natural colour of juice, not by changes in the pigments themselves. The colour pigments of orange juice are quite heat-stable compared with colour pigments in other foods. The formation of brown-coloured compounds occurs after excessive heat treatment or long storage at room temperature.
TABLE 2.4 AVERAGE VITAMIN C CONTENT IN SOME FRUITS Fruit
Peach Apple Blackberry Kumquat Grapefruit Orange Papaya Kiwi fruit Strawberry Guava Blackcurrant
Average vitamin C, mg per 1000 g edible fruit 80 80 210 380 390 530 620 630 660 1840 2100
Source: Svenska statens livsmedelsverk, Livsmedelstabell
Typical values for vitamin C in freshly extracted juice range from 450 to 600 mg/litre. Provided that the production procedures are correct, only a small loss of vitamin C occurs during the initial processing into concentrate. More significant losses may occur during processing at the juice packer and during ambient storage. Typical values for orange juice when consumed range from 200 to 400 mg/litre. Vitamin C is essential for the synthesis of collagen, the most abundant protein in mammals. Collagen is the major fibrous element of skin, bone, blood vessels and teeth. A lack of vitamin C leads to scurvy, which causes loss of teeth, bleeding skin and ulcers. Vitamin C is sometimes suggested to have an anticancer effect by its reaction with and inactivation of free radicals in the body. A wide range of other beneficial effects of vitamin C are also suggested. However, contrary to popular belief, it has never been shown clinically that vitamin C has a preventive effect on the common cold.
2.2.5 PROMOTING HEALTH
A number of compounds present in juice contribute to its health-promoting image. Some of these are discussed below. Ascorbic acid
Ascorbic acid – vitamin C – is the most important nutrient in orange juice. One of the reasons for this is that consumers regard oranges as a good source of vitamin C. Some other fruits contain more vitamin C than oranges but few are as popular, see Table 2.4. The level of vitamin C in freshly extracted orange juice may vary a lot depending on orange variety and growing conditions.
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2.2 Important properties of orange juice
TABLE 2.5 THE NUTRIENT COMPOSITION OF FRESHLY EXTRACTED ORANGE JUICE
Constituent Protein (total Nx6.25), g Amino nitrogen, g Fat (ether extract), g Soluble solids, total, g Sugar, total as invert, g Reducing sugar, g Sucrose, g Acid, total, g Malic acid, g Mineral nutrients as ash, g Calcium, mg Chlorine, mg Fluorine, mg Iron, mg Magnesium, mg Phosphorus, mg Potassium, mg Sodium, mg Sulphur, mg Ascorbic acid (vitamin C), mg Betain, mg Biotin, mg ß-Carotene, mg Choline, mg Flavonoids, mg Folic acid, mg Inositol, mg Niacin, mg Pantothenic acid, mg Pyridoxine (B6), mg Riboflavin (B4), mg Thiamine, B1, mg Vitamin B12, µg
Content per 100 g Range 0.58–1.29 0.029–0.07 0.0–0.66 8.1–17.7 6.23–14.3 2.25–8.83 2.98–6.24 0.58–1.73 0.10–0.17 0.27–0.70 6.3–29.4 3.6–13.2 0.11–0.19 0.1–0.8 9.8–17.1 8.0–30.0 116–265 0.2–2.4 3.5–11.3 26–84 41–47 0.0001–0.00037 0.23–0.28 7–15 80–118 0.003–0.007 170–210 0.13–0.46 0.06–0.3 0.023–0.094 0.013–0.059 0.057–0.106 0.0011–0.0012
Average 0.91 0.047 0.2 12.3 9.15 4.60 4.37 1.09 0.15 0.41 15 6 0.14 0.3 12 20 196 0.5 8 56.6 44 0.00024 0.12 11 99 0.004 194 0.26 0.13 0.038 0.021 0.077 0.0011
Source: adapted from Redd and Praschan.
Flavonoids and pectin are believed to be linked to the reduction of blood serum cholesterol in humans. The flavonoid hesperidin can, however, cause problems during orange juice production as it precipitates out as white flakes in the evaporator. A number of other nutrients like thiamine and potassium are also found in orange juice but not in larger amounts than found in other fruits and vegetables. A comprehensive list of nutrients in freshly extracted orange juice is given in Table 2.5.
Other nutrients
Folic acid is also found in significant amounts in orange juice. This B vitamin is required for DNA synthesis and its deficiency is first expressed in tissues with high rates of cell turnover. Pregnant women are prone to folic acid deficiency which, in rare cases, may affect the foetus. Folic acid is quite heat-sensitive, but the vitamin C in citrus juice protects it from degradation during heat treatment.
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2.3 Orange juice categories
Ready to drink NFC or direct juice
RTD juice made from concentrate
Fig. 2.3 Main orange juice categories.
For dilution FCOJ 41–52 °Brix
2.3.1 READY-TO-DRINK ORANGE JUICE
Ready-to-drink (RTD) orange juice is at the strength at which it will be consumed. It does not require dilution before drinking. Some categories of RTD orange juice are given below. Freshly squeezed orange juice
2.3 Orange juice categories
Juice packaged directly after extraction but without pasteurisation or any other physical or chemical treatment. Its shelf life is very short.
Quality parameters as defined in product specifications and grade standards provide orange juice buyers and sellers with appropriate information about the product they are handling. This applies to any link in the production chain. To the consumer, however, orange juice covers a wide range of products, many of which are not well-defined. Many different terms are used within orange juice marketing to describe the various products. Several of these terms are not consistent and have different meanings in different countries. Nevertheless, along with the increase in global trade and marketing of orange juice, there is growing pressure to harmonise the terms used. Orange juice products can be divided into two main categories – ready-to-drink juices and concentrates. The latter require dilution with water before consumption. Ready-to-drink juices are either NFC or reconstituted from concentrate.
Fresh orange juice
A misleading term that should be avoided. Sometimes it is used to mean freshly squeezed orange juice, in other markets it is used for juice distributed chilled (NFC or made from concentrate). Not-from-concentrate juice (NFC)
Juice which has neither undergone a concentration step nor dilution during production. This term originated in the USA. Premium juice
A term which has been used in the USA and Canada for NFC for marketing purposes. Direct juice
A term sometimes used in Europe for NFC. The expression “not from concentrate” is felt to imply to consumers that juice derived from concentrate is inferior to NFC. In European legislation NFC is defined simply by the term fruit juice.
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2.3 Orange juice categories
Pure juice or 100 % juice
Orange juice drinks
Often used on a label to define pure juice, being a direct juice or one made from concentrate to distinguish it from nectar.
Drinks with a lower juice content than nectars. They are not subject to juice legislation but to general food legislation. In some cases they may contain only peel oil and flavouring agents.
Orange juice from concentrate
This product is also known as orange juice made with concentrate. The juice is produced by diluting orange concentrate with potable water.
Orange flavour drinks
Products tasting of orange but containing no genuine juice product. 2.3.2 CONCENTRATED ORANGE JUICE
Concentrated orange juice is diluted to single strength before consumption. The most common orange concentrate products for the trade and retail sectors are given below.
FORTIFIED ORANGE JUICES
Juice with added floating pulp
This is juice with added floating cells (also known as pulp or fruit meat). The product is sometimes called Home style, Natural, etc. The added cells provide mouthfeel and increase the natural fibre content of juice. Juice without floating cells is referred to as “smooth”.
Frozen concentrated orange juice (FCOJ), 65–66 °Brix
The standard product for traded orange juice concentrate. It is concentrated approx. 5.5 times. It is a bulk product only, stored and shipped at –6 to –25 °C. The term may be misleading as FCOJ at such high concentration does not freeze solid but is still pumpable.
Vitamin enriched
Both naturally occurring vitamins and man-made vitamins can be added by packers to increase the nutritional value of orange juice. Calcium enriched
FCOJ at approx. 55 °Brix
Calcium compounds, which are soluble in juice, are added to juice by the packer to increase its nutritional value.
This product is often referred to as Dairy Pack. It is a bulk product only. It is 66 °Brix concentrate cut back (rediluted), e.g. with single-strength juice and pulp, to the required concentration. No further additions are needed at the juice packer apart from water dilution. This product is commonly used by dairies.
Fibre enriched
Addition of nutritional fibre (normally not from oranges) to increase the health value of juice.
FCOJ at min. 41.8 °Brix
RTD ORANGE PRODUCTS WHICH MAY NOT BE CALLED ORANGE JUICE
A retail product, mainly in US, for dilution with water (3 times) to single strength at home, in restaurants, etc.
Orange nectar
Orange juice with added sugar, acids and/or water. The minimum fruit content varies according to legislation. For orange nectar, EU regulations stipulate min. 50 % fruit juice content at RTD strength.
Concentrate at approx. 52 °Brix
A retail product aseptically packaged, mainly in Scandinavia. For dilution with water (4 times) to single strength at home, in restaurants, etc. It is distributed chilled or at ambient temperature.
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2.4 Regulations governing juice origin
In the USA, standards governing the composition and labelling of food and the use of additives are under the administration of the Food and Drug Administration (FDA) and the United States Department of Agriculture (USDA). The standards for orange juice identity (or juice origin) are enforced by the FDA, whereas the standards for orange juice grades (more or less the quality) are enforced by the USDA. In the European Community, legislation covering fruit juices and fruit nectars is based on a Council Directive concerning fruit juices and similar products. The current directive 2001/112/EC came into force in 2001 and EU countries were given until 2003 to comply with it. The demands for labelling are outlined in the Council Directive on labelling, although specific labelling requirements are given in the fruit juice Council Directive. Countries in other regions have similar legislation to that of the US and EU. Countries not having their own legislation refer to the Codex Alimentarius published by the FAO. There is a general desire worldwide to harmonise orange juice standards to promote free and open global trading. This is an objective of the Juice Products Association (JPA), whose members are drawn from the United States, Canada, Mexico, Central and South America, and Europe. The JPA’s position is that the USDA standards covering the grade and quality of orange juice should be applicable throughout the major citrus juice producing countries. It even suggests that USDA standards should be adopted as a worldwide harmonised standard. There are ongoing discussions with European and other authorities on this topic. An overview of the most important aspects of legislation in the US, EU and other countries are found in Section 11, Standards and Regulations.
2.4 Regulations governing juice origin In the European Union and several other countries, the term ‘orange juice’ may only be used for juice extracted from sweet oranges, Citrus sinensis. In the USA, regulations allow for up to 10 % of tangerine or hybrid orange/tangerine juice to be included in orange juice. Also Codex Alimentarius allows for 10 % mandarine juice. These added juices can improve the colour and flavour of the blended juice. In principle, regulations governing direct juice, or NFC, require that flavour and pulp removed during processing should be added back to the same juice. For reconstituted orange juice, water should be added back to the minimum concentration defined in the quality standard applied in a country. Essences should be added back to restore flavours, and pulp may be added to achieve the desired properties of the final juice product. Orange juice should come from the endocarp of the fruit and be extracted by mechanical means. The EU directives for fruit juices of 2001 allow pulp wash in orange juice from concentrate, but not in direct (NFC) juice. In-line addition of pulp wash is also allowed in the US (up to 5 %) and many other countries. Although attempts are being made continually to reach consensus between legislation in different global trading blocs, regulations governing fruit juices and other beverages still vary worldwide. In general, legislation covers: • product origin • how juice processing may be carried out • the composition and quality of fruit juices • product labelling
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3
The supply chain and global consumption of orange juice
In section 3 you will read about: • How FCOJ is traded as a commodity product and the significance of the futures market to bulk trading. • Import duties with examples in certain trading blocs and countries. • The amount of orange juice products consumed in major markets.
• The structure of the orange juice industry. • The evolving relationship between orange growers and fruit processors. • How marketing processors and bulk processors operate. • The activities of blending houses, juice packers and soft drink producers. • The fluctuations in the worldwide pricing of bulk juice products.
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3. The supply chain and global consumption of orange juice Pricing and trading Special terminals for handling frozen concentrate in bulk are located in major ports. The world market price of FCOJ fluctuates according to its supply and demand. Freecarrier Rotterdam warehouse is a common standard for FCOJ (66 °Brix) traded prices, which include freight charges to the port of Rotterdam, the Netherlands. The futures market enables the citrus industry to manage commercial risks. It also sets a value for FCOJ. The speculative activity of the futures market provides the finance needed to transact commercial hedges and set price levels. In addition to long-term contracts there is also a spot market for FCOJ. Quite large differences in import duties for orange juice exist between importing countries. As regards the consumption of orange juice, the USA and Europe are the largest markets.
Summary Orange juice products usually change hands many times along the supply chain. It is thus important for all involved in the intermediate steps to be familiar with the total sequence of juice production. In Florida, orange growers are becoming diversified agribusiness companies. In Brazil, the large orange processors still get part of their fruit from their own groves. So-called marketing processors produce and sell their own juice brands. Bulk processors mainly sell their products in bulk form. Blending houses provide concentrate and bases of consistent quality according to defined customer specifications. Juice packers treat bulk product as required and then pack it in consumer packages. Soft drink producers may use orange concentrate and prepared bases from blending houses as raw materials.
3.1 The chain of supply
Industry structure
There are many links in the chain of supply for orange juice – from ripe oranges ready for picking to the consumer opening a carton of juice at a distant location (see Figure 3.1). The product usually changes hands several times along the way. It is thus important to be familiar with the complete sequence of juice production in order to understand the commercial conditions for each type of company forming the intermediate links in the supply chain. This section refers generally to orange juice production in Florida and Brazil, which dominate the world juice market.
Full vertical integration – i.e. having all the steps from fruit harvesting to distribution of packaged consumer product under one roof – is rare in the orange juice industry. This has resulted not only from geographical factors but also from the way the industry has matured. There is a trend for each link in the production chain – growers, fruit processors, juice packers and retailers – to become independent businesses. This may be a natural consequence of the marketplace demanding increased and specialised competence at each step of the production sequence. It may also be partly due to commercial factors, such as long-term supply contracts and the futures market, that allow individual sectors of the citrus industry to reduce their own commercial risk from market price fluctuations.
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3.1 The chain of supply
Oranges Packaged juice – reconstituted and NFC
Packaged juice and juice drinks
Fruit processors
Bulk concentrate and NFC
By-products Bulk concentrate and NFC
Juice packers
Still and carbonated soft drinks
Fig. 3.1 The supply chain from fruit harvest to consumers. Soft drink bases
Blending houses
Soft drink producers
The orange-growing and processing industry undergoes constant change in line with evolving commercial and political conditions. On the growers’ side, in Florida there has been a shift from independent farmers to diversified agribusiness companies that are active in marketing and interested in long-term business relationships. Moreover, in Florida during the 90’s, growers divested themselves of juice production, and processors who had until then owned their own groves instead formed partnerships with growers. Long-term agreements between processors and growers ensure the stable supply of raw materials. There are several organisations promoting the interests of Florida citrus growers to give them a stronger marketing and negotiating position than their counterparts in other countries. In Brazil, the large orange processors still get part of their fruit (20 %) from their own groves. The remaining fruit is mostly obtained by long-term contracts with medium- and largesize growers.
3.1.1 GROWERS
Orange growers manage the groves, harvest and sell the orange fruit. They are organised in many ways – from small independent growers selling their fruit to a fruit handler or through a cooperative, to growers who are part of a large fruit processing company. For the fruit processor it is essential to secure a continuous supply of oranges in sufficient quantities and at the right price. Traditionally, many orange processors have owned the groves needed to supply them with all or the majority of fruit required throughout a season. This is particularly important during periods of uncertain fruit supply and unstable prices, e.g. as was experienced during the Florida freezes in the 1980’s. Today, however, the supply of fruit is abundant in most regions, although the drop in concentrate prices has made alternative outlets for fruit more interesting than concentrate production.
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3.1 The chain of supply
The largest marketing processors are based in Florida, such as Tropicana, the leading NFC producer, and Citrus World. They process fruit into juice and fill it into retail packages at their own facilities. They also purchase additional juice in bulk form from other bulk processors. For marketing processors, the control of product availability is regarded as more important than ownership of manufacturing assets. As an example, Coca-Cola now focuses on marketing and distributing Minute-Maid brands, while the production facilities are owned and operated by a Brazilian bulk processor, Cutrale. The majority of orange juice worldwide is produced by bulk processors. Bulk delivery is most important to the large Brazilian processors. They do not possess their own consumer brands, one reason being to avoid competing with their bulk juice customers. Several joint ventures have been created for the rapidly growing NFC market in South America. Brazilian bulk processors pack retail products at their facilities as co-packers for companies that have their own branded products and distribution and marketing chains. The bulk products are transported in ship tankers, tank cars or in individual containers, such as 200 litre (55 gallon) steel drums and one tonne bagin-box containers. Efficient transport is crucial for these commodity products. (See also Section 6.) Several terminal installations around the world are dedicated to receiving and shipping frozen concentrated orange juice (FCOJ) using tankers. The larger Brazilian processors own terminals in Brazil for exporting bulk products from Brazil, and in Europe, the USA and Japan for importing FCOJ into these markets. These companies also own several large tanker ships designed and dedicated to transporting FCOJ. Recently, bulk ships and terminals dedicated to handling chilled aseptic NFC from Brazil have also come into operation. Bulk processors make their money from the difference in bulk concentrate prices and fruit prices – the bulk processing margin. Florida bulk processors are very vulnerable to the wide fluctuations in FCOJ prices.
Growers
Fruit handlers
Fruit processors
Fig. 3.2 The supply of oranges to fruit processors. How growers are paid
Fruit quantities are often quoted in “field box” units. Based on Florida practice, one box is defined as 90 lb (40.8 kg) of oranges. In Florida, payment to growers is not based on the weight of delivered fruit but on the amount of soluble solids (juice sugars) obtained from the fruit. The quantity of soluble solids is calculated from the volume of juice extracted from the fruit multiplied by the °Brix level of the juice. The amount of extracted juice is determined by squeezing a sample of oranges on a “State test extractor”. Oranges rejected during screening at the processing plant fruit reception area are not paid for. In Brazil, payment to the growers was made traditionally according to the gross weight of delivered fruit, including rejects. Payment today is still based on fruit quantity although the contract format has changed. Standard contracts with payment to growers based on FCOJ world market prices were abandoned in the mid 90’s and replaced by free negotiations. 3.1.2 TYPES OF FRUIT PROCESSOR
In short, orange processors take in fruit and process it to produce concentrate and NFC. They can be divided into two groups: • marketing processors • bulk processors Marketing processors sell packaged juice under their own brand name, which requires retail and consumer marketing skills. Bulk processors mainly sell their products in bulk form, which requires skills in the efficient distribution and marketing of a commodity.
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3.1 The chain of supply
Bulk processors Long-term contracts
Trading companies
Long-term contracts
Blending houses
Juice packers Long-term contracts
Spot purchases
Spot market
Fig. 3.3 The orange juice supply chain from bulk processors.
Therefore they need to take advantage of the commodity trading market (and to benefit from its commercial protection) in a similar way to their Brazilian counterparts. The links between Florida and Brazil strengthened during the 1990’s. The major Brazilian bulk processors acquired several juice facilities in Florida and operate 8 plants (2002) contributing to about half of Florida’s juice production. Operating in both markets offers benefits such as higher trading efficiency and balancing concentrate quality. NFC, which has had a high growth rate in Florida and now accounts for more than a 40 % share there, offers better margins than FCOJ for Florida juice producers. Bulk processors supply NFC to juice packers and marketing processors but some also co-pack in their own facilities. The links between Florida and Brazil strengthened during the 1990’s. The major Brazilian bulk processors acquired several juice facilities in Florida and operate 8 plants (2002) contributing to about half of Florida’s juice production. Operating in both markets offers benefits in trading efficiency and balancing concentrate quality. The different routes that orange juice products take from bulk suppliers are shown in Figure 3.3.
season and operating conditions change in the plant. Juice packers, however, need to buy raw juice of defined quality as they, in turn, need to supply the market with uniform products over the long term. The need for consistent juice quality has created the industry segment “blending houses”. Although they normally work with many different fruit juices, orange juice is a primary product for blending houses. Their purpose is to provide juice packers with a concentrate (and sometimes also NFC) that consistently meets defined quality specifications. They achieve this by blending concentrates of different origin and adding flavour fractions, often according to customer-specific recipes. In addition to supplying the defined juice product, blending houses normally have specialist product know-how which is made available to their customers. (Blending house operations are also discussed in Section 6.) Blending houses are often located in or near the main ports receiving juice concentrates. The larger Brazilian processors who have their own terminal facilities also offer blending house operations. The preparation of soft drink bases is another important business activity of those blending houses which have developed from flavour-manufacturing operations. Purchasing concentrate from a blending house is generally more expensive than buying it on the spot market. However, the buyer can be assured of product quality meeting his demands.
3.1.3 BLENDING HOUSES
Consistent quality between batches of FCOJ cannot be maintained during processing. Variations in flavour profile, Brix:acid ratio, pulp levels, etc., are unavoidable because fruit varies during the
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3.1 The 3.1 chain The ofchain supply of supply
2500
USD/tonne
2000
1500
1000
500 88
89
90
91
92
93
94
95
96
97
98
99
00
01
02
03
Year
Fig. 3.4 World market for FCOJ (Brazilian export prices Rotterdam) Source: Foodnews
Fluctuations in world market prices for FCOJ, not always reflected in retail prices, put pressure on juice packers. For a successful operation, the juice packer requires important skills in several areas:
3.1.4 JUICE PACKERS
Juice packers take in bulk product, treat it as required and then pack the product in consumer packages. The juice packer may also control the distribution of the packaged product. Juice packer operations are described in more detail in Section 7. As with fruit processors, there are two main categories of juice packer – those who market their own brands and those who focus on copacking, e.g. for private label brands. There are dedicated juice packers and dairies with juice packing operations. The product range of juice packers may include nectars and fruit-based still drinks in addition to 100 % pure juices.
Sourcing: raw material costs constitute a major share of the total costs. The right juice quality and favourable contracts are vital to overall profitability. Processing/Packaging: where the focus is on maintaining product quality and keeping running costs, including product losses, low. Distribution: distribution of packaged product also accounts for a significant share of the total costs, and efficient distribution therefore plays an important part in overall profitability.
packers treat bulk “Juice product as required and
Marketing: marketing skills are important to both packers who market their own brands and those who focus on co-packing.
then pack the product in consumer packages
”
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3.2 World market pricing for bulk juice products
In the mid 1990’s world market prices for FCOJ (66 °Brix) were quite stable around 1,500–1,600 USD/tonne CIF Rotterdam because of efforts made by the Brazilian export association, ABE. However, new producers entering the market and large FCOJ stocks remaining after a cold European summer led again to a slump in prices, as low as 700 USD/ tonne. In the early 2000’s price levels remained around 1,000–1,200 USD/tonne. Although these levels are claimed to be near or below break-even for most juice processors, the purchasing market did not allow increases in price levels. Brazil is the dominant world exporter of frozen concentrate and Europe the largest market, with import harbours in Belgium and the Netherlands. Rotterdam is a commonly used reference for FCOJ world market prices. Freecarrier warehouse means that the price includes freight charges to the port of Rotterdam in the Netherlands, and loading product, e.g. on road tankers. But import duty and transport costs from the tank farm to the user need to be added. Price levels for Florida FCOJ are given in a different unit, US dollar per pounds solid, which is quoted free on-board carrier in Florida. Hence the bulk price does not include overseas transport, but this is not normally required as the main market is North America. FCOJ world market prices are set in US dollars. Variations in the Brazilian currency against the US currency influence the Brazilian processors’ margins. For European markets, the exchange rate of the Euro against the US dollar will influence retail juice prices. As regards the market for juice supply, the extensive planting of new trees seems to assure an adequate supply of fruit and orange juice concentrate in the foreseeable future. Nevertheless, a reduction in Brazilian output due to adverse climate effects or diseases can alter this outlook.
3.1.5 SOFT DRINK PRODUCERS
Although the term soft drinks strictly means all non-alcoholic drinks, the name soft drink producers is commonly applied to manufacturers of retail packaged carbonated beverages and fruitflavoured still drinks. The soft drink producer may use orange concentrate as a raw material, but often he purchases a prepared base from a blending house. For drinks of low fruit content, the flavour of FCOJ is not strong enough and so it has to be enhanced with additional flavours. Other ingredients in the soft drink base may be emulsifiers and preservatives. At the soft drink producer, only sugar, acid and water (plus carbonation as required) need to be added to a ready-prepared base. A few large multinational companies and many local companies can be found among the soft drink producers. As with juice packers, blending house specialists may provide a valuable source of experience and product knowledge for small to medium-sized soft drink producers. Blending houses may also help in developing new soft drink products and in responding to new consumer trends.
3.2 World market pricing for bulk juice products World market prices for FCOJ have shown wide fluctuations over the years. Prices increased during the 1980’s as freezes in Florida reduced orange supplies. Prices dropped between 1992 and 1994 as large harvests were again recorded in Florida. In the autumn of 1994 a severe drought in Brazil once more led to sharply rising prices for frozen concentrate. (See Figure 3.4.) In general there is a correlation between FCOJ price levels and expected supply, but in the past over reaction by the market has resulted in very wide price fluctuations. This usually constitutes an undesirable situation for both suppliers and juice purchasers.
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3.3 FCOJ commodity trading and the futures market
3.3 FCOJ commodity trading and the futures market
UNITS USED FOR BULK JUICE TRADING
The buying and selling of FCOJ have evolved into commodity trading. Two of the largest Brazilian bulk juice producers, Louis Dreyfus and Cargill (both also producing in the USA), are major commodity trading companies active in several other fields besides citrus. They have influenced the trading of citrus on the commodity trade market. Commodity products, which are usually supplied in well-defined units, can be traded on the “futures” market. “Futures” are contracts agreed for the future delivery of a physical commodity, such as FCOJ. Cash price is the price at which the actual commodity is selling for.
On the world market, frozen concentrates of Brazilian and other origin are usually traded per metric tonne product, with prices given as USD/tonne concentrate. In the USA, however, the basic unit for pricing orange fruit, singlestrength juice and FCOJ is the content of soluble solids (in principle the sugars), not the weight or volume of product. The unit used is lb. soluble solids. The US futures market also use lb. soluble solids to define product quantity. The following approximate factors can be used when converting prices: For FCOJ of 66 °Bx 1000 USD/t conc. 1430 USD/t conc.
Risk management and price setting
0.70 USD/lb solids 1.0 USD/lb solids
For NFC juice of 11.8 °Bx 1000 USD/t juice 3.82 USD/lb solids 260 USD/t juice 1.0 USD/lb solids
The futures market provides a means of managing risk for the citrus industry, a way for all involved to hedge (protect against financial loss) their risk exposure caused by fluctuations in cash prices for products. Futures markets require the participation of both hedgers (risk shifters) and speculators (risk assumers). Hedgers are those in the citrus industry, such as fruit processors and sellers, who transfer unwanted risks associated with their normal commercial activities. Speculators (nonproducers/processors) seek financial gain by cor rectly predicting changes in future price moves. The speculative activity provides the finance required to carry out commercial hedges. In addition to risk shifting, the futures markets also sets the value for one pound of FCOJ solids, known as price discovery.
Trading of FCOJ futures takes place through the Citrus Associates of the New York Cotton Exchange, NYCE. This nonprofit organisation provides the physical location where FCOJ futures and options are traded (by voice and hand signals), and oversees the regulations governing all transactions. It forms part of New York Board of Trade, NYBOT. The regulations define quantities of FCOJ to be contracted and the time periods allowed for trade and delivery of contracts (every other month). Grade standards for product quality, as well as product identification and inspection, are also specified in the regulations.
38
3.4 Import duties and juice imports
In 2004, a new form of futures contract was introduced that recognised the Florida/Brazil origin of FCOJ in order to more correctly follow cash market transactions, which tend to value FCOJ from Florida and Brazil differently to that of other origins. The futures market is important to the citrus industry, not only as a tool for risk management but also as a price basis for purchasing fruit and for sales contracts for bulk concentrate. The NYCE provides hedging opportunites for citrus industry players active in Florida, but there is no similar futures exchange providing risk management in São Paulo. The profit of bulk juice processors comes from the price difference between the fruit and concentrate. Therefore they must posses good skills in marketing a commodity product and risk management. In addition to long-term sales contracts there is also a spot market for FCOJ, delivered from tank storage and in drums. Trade on the spot market is high when price levels are unstable. Products on the spot market may be of less well-defined quality or product specifications and thus command lower prices. During periods of depressed retail prices for orange juice, juice packers may be forced to acquire large volumes of such juice on the spot market.
3.4 Import duties and juice imports There have been long-lasting negotiations between trading blocs aimed at reducing trade barriers and promoting freer trade, including that of citrus products. Examples are the GATT (General Agreement on Trade and Tariffs) where major agricultural agreements were established in the Uruguay round of talks held in 1994. The North American Free-Trade agreement, NAFTA, intended to reduce trade barriers between USA, Canada and Mexico was reached in 1994. Work on a similar agreement to also include all countries in South and Latin America, Free-Trade Area of the Americas or FTAA, was initiated in 1998. Although scheduled to come into force in 2005, the participants are still discussing many issues involved with the agreement. Since both Brazil and Florida, the major orange juice regions, are part of the FTAA, the agreement would have a significant impact on orange juice trade. The Florida citrus industry are carefully evaluating the likely impact on Florida orange growers and the juice market.
SOME TERMS USED WITH TRADE TARIFFS Ad Valorem tariffs: duty calculated as a percentage of the value of the imported product. Freight costs are included in the product value. Specific tariffs: a duty of a fixed amount of money per unit of juice independent of the value of the product. Quota: defined maximum quantity of product which is allowed, e.g. at a lower import duty. SSE or single-strength equivalent: FCOJ calculated as the volume of juice it would yield when reconstituted to single-strength juice. GATT: General Agreement on Trade and Tariffs. NAFTA: North American Free Trade Agreement.
39
3.4 Import duties and juice imports
3500 3000
Thousand tonnes
2500 2000 1500 Others
1000
Japan USA/Canada
500
EU
0 1996
1997
1998
1999
2000
Years
Fig. 3.5 The major juice import markets. Source: FAO
For orange juice, there are quite large differences in import duties between the various importing countries. Duties often depend on the exporting country, for example, several exporting countries have agreements with respective importing markets which enable duty-free or reduced import tariff. In general, however, such agreements do not apply to the major exporters, Brazil and the USA. The US “duty drawback” procedure favours the export of juice from the US. In the duty drawback system juice exporters/importers can recover the import duty paid for a certain volume of juice if they export the same volume and kind of product. US import duties distinguish between
FCOJ and NFC. Tariffs are higher for FCOJ than NFC (calculated as single-strength juice.) In general, citrus growers and fruit processors receive little or no subsidies. Within the EU, however, significant subsidies are paid to orange processors who purchase fruit from EU fruit growers at the minimum recommended fruit prices. The European Union is the largest juice import market, followed by the USA. The relative sizes of the major juice import markets are shown in Figure 3.5. The consumption of packaged orange juice per region is shown in Figure 3.6.
Million litres
5000 4000
4341
3000 2000
2451
1000 1206
240
Asia/Pacific
S&C America
0 USA/Canada
W Europe
Fig. 3.6 Consumption of packaged orange juice in certain regions, 2003. Source: Euromonitor
40
3.4 Import duties and juice imports
• Mexico Phasing down to duty-free unlimited import by 2008 (NAFTA agreement) For 2003: – within quota for FCOJ, 4.6 USD/100 l SSE – within quota for NFC, 1.8 USD/100 l SSE • Most Favoured Nation (e.g. Brazil) FCOJ 7.9 USD/100 l SSE NFC 4.5 USD/100 l SSE
3.4.1 IMPORT DUTIES WITH SOME TYPICAL EXAMPLES European Union
Tariffs for orange juice imported into the European Union vary greatly depending on the exporting country. The dominant share of juice imported into Europe comes from Brazil and is subject to import duty for Most Favoured Nation (MFN). This duty, which was 20 %, has gradually been lowered under GATT, and is differentiated according to the degree of concentration and temperature. EU import duties are ad valorem (a fixed percentage of the product value including freight). Some import tariffs in effect in 2002 are presented in the list below: • From EU countries and some non-EU Mediterranean countries, 0 % • Mediterranean Basin Preference (mainly Israel and Morocco) – within quota, 2.3 % – exceeding quota, 5.7 % • Lomé convention countries, 0 % (African, Caribbean incl. Belize and Costa Rica, Pacific) • Most Favourable Nation (MFN) tariff (applies to countries such as Brazil and USA) – FCOJ at -18 °C, 15.2 % – FCOJ at -10 °C, 12.2 % • Mexico – within quota for FCOJ, 3.8 % – exceeding quota imported at MFN tariff
The USA implements a “duty drawback” procedure. This allows US importers of FCOJ who also export FCOJ or reconstituted orange juice to be reimbursed 99 % of the import duty paid on the same quantity of imported concentrate as was exported within a 3-year period. NFC exports are not eligible for drawback against imported FCOJ. Canada
Canada allows orange juice concentrate to enter duty-free but levies import duty on singlestrength juice. All juice imports from NAFTA countries (USA and Mexico) are tariff-free. Japan
Until 1979 there was little fruit juice import into Japan due to very low import quotas. The quotas were gradually increased until they were removed altogether in 1992. Import duties are ad valorem. • Most Favoured Nation tariff FCOJ, 25.5 % Republic of Korea
Until 1989 juice imports were restricted by very low quota. Following GATT agreement, quotas for orange juice imports were removed in 1997. • Most Favoured Nation tariff for FCOJ and juice ad valorem, 55 %
USA
Import duties are specific in the USA. The rates, differentiated for FCOJ and NFC, are given as a fixed fee per pound of soluble solids. Some of the current duties, converted to US dollars per 100 litres single-strength juice, are given in the list below. Most US juice imports are as FCOJ and the largest exporter is Brazil, which is subject to full MFN duty. • Caribbean Basin Initiative beneficiary countries (e.g. Belize, Honduras, Costa Rica), 0 % • Israel (as of 1995), 0 %
China
Following China’s WTO entry, tariffs for imported orange juice have decreased significantly. Tariffs are ad valorem: • Frozen juice Most Favoured Nation tariff, 7.5 % • Nonfrozen single-strength juice MFN, 32 %
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3.5 Global orange juice consumption
Million litres
0
200
400
600
800
Austria Belgium Denmark Finland France Germany Greece Ireland Italy Netherlands Norway Spain Sweden Switzerland UK Canada Brazil China South Korea
Fig. 3.7 Consumption of packaged orange juice in European and other countries, 2003. Source: Euromonitor
has gradually increased to take more than 40 % market share. RTD juice made from concentrate accounts for about 40 %. Virtually all RTD orange juice in the US is distributed refrigerated (4 °C). See also section 10.3. In Europe, nearly all retail orange juice is RTD, there is very little concentrate. The total orange juice volume for Western Europe in 2000 was about 3 billion litres. European consumption has had a high growth rate – almost doubling between 1983 and 1993 – but since then growth has slowed down to about 3 % annually. Most orange juice in Europe is made from concentrate. The consumption of NFC has increased over the last decade and now accounts for more than 10 % of total orange juice sales. The growth in per capita income and the perception of NFC quality as being similar to that of fresh fruit have driven the increase in NFC sales despite its high price premium.
3.5 Global orange juice consumption North American and European markets are the largest consumers of orange juice. The USA and Canada account for some 50 % of total global consumption of packaged orange juice, whereas Western Europe consumes about 30 % of the total volume. (See Figure 3.6.) In the USA, consumption of orange juice, about 5 billion litres/year in 2001, has remained fairly constant over the past decade. Nevertheless, there has been a constant shift in market share for the three main types of orange juice in the US market: frozen concentrate for home dilution, ready-to-drink (RTD) juice made from concentrate, and NFC. Frozen concentrate has steadily decreased from a dominant position to less than 15 % of total orange juice retail sales. NFC, which emerged on the US orange juice market in the mid-80’s,
42
3.5 Global orange juice consumption
Litres / capita/year
20 15 16.6 10 13.8 5
8.3 2.7
0 USA
UK
Germany
Japan
Fig. 3.8 Per capita consumption of orange juice in some countries, 2002. Source: Canadean
NFC is retailed at up to double the price of orange juice made from concetrate. Compared with FCOJ, the 5–6 times larger storage and shipping volumes for NFC combined with the stricter quality demand on raw fruit for NFC result in a significantly higher cost for bulk NFC imported into Europe. During the introduction of NFC in Europe the market was dominated by Florida juice, but today NFC is often a blend of origins. In other markets, a rapid growth in the consumption of packaged orange juice is noteworthy in South America, particularly Brazil. Some Far East markets such as Japan and the Republic of Korea have also shown large growth rates, although these may fluctuate from year to year due to economic factors. Large cities in the coastal region of China constitute an area with high economic growth and a rapidly growing demand for orange juice. Eastern European counties are also rapidly expanding markets The consumption of packaged orange juice in European and other countries is shown in Figure 3.7.
3.5.1 PER CAPITA ORANGE JUICE CONSUMPTION
The USA is not only the largest total consumer of orange juice worldwide, but it also has the highest consumption per capita, some 16 l (4.2 US gal.) per person per year. Per capita consumption in the UK comes second, where orange juice accounts for the highest share of all fruit juice with more than 70 % of the market. Although Germany has the highest total fruit juice consumption in Europe, because apple and blends dominate, the per capita orange juice consumption is much lower than in the UK. The per capita estimates in Figure 3.8 are based on data collected by market organisations and refer to 100 % orange juice. The Florida Department of Citrus (FDOC) also estimates the overall orange juice utilisation in major markets. This is the “presumed consumption”, which is based on so-called “disappearance data”, or net utilisation of bulk orange concentrate and NFC. This means that orange concentrate used to produce nectars and fruit drinks is also counted as orange juice consumption. The values presented by the FDOC are therefore higher than the actual consumption of 100 % juice only. However, they provide a valuable understanding of the total usage of processed orange juice in different markets.
43
3.5 Global orange juice consumption
44
4
Principles of processing orange juice
In section 4 you will read about: • How the different steps of juice processing and bulk storage affect the quality of orange juice. • How oxygen gets into juice and its role in degrading juice quality and causing problems during operation. The removal of oxygen from juice is also discussed.
• Which microorganisms cause juice spoilage and the influence of raw materials and cleaning procedure on product contamination. • Why and when pasteurisation is carried out and the conditions needed for effective heat treatment.
45
4. Principles of processing orange juice Summary A good understanding of the properties of orange juice is required to design and operate processing plants that maintain high juice quality. The properties of fresh fruit and the initial processing conditions (during juice extraction) influence the quality of the end product. Heat treatment of juice is essential for obtaining the desired product shelf life, but the process should be designed to minimise unwanted quality degradation. Bulk storage conditions that minimise changes in quality are essential because juice may be stored for a year or more.
packages. It is therefore essential to prevent air from entering product streams, and to remove it before filling and packaging. Orange juice is a high-acid product which limits microbial growth to acidtolerant bacteria, yeasts and moulds. Yeast fermentation is the prime cause of microbial spoilage in aseptically packaged juice. Effective cleaning procedures are essential in controlling microbial contamination. Pasteurisation of orange juice is necessary for inactivating enzymes and for destroying microorganisms capable of growing during storage. Enzyme activity leads to cloud loss in single-strength juice and gelation in orange juice concentrate. The relevant enzymes in orange juice require a higher heat load to be inactivated than that for microorganisms.
Minimising loss of quality Air in juice leads to reduced product quality, foam during deaeration and filling, and uneven distribution of floating pulp (if any) in
Raw materials Quality Treatment
Processing Heat treatment Oxygen
Bulk storage Temperature Time
Packaging Barriers Hygiene
Shelf storage Temperature Time
Fig. 4.1 Factors which influence juice quality.
into consideration in designing and operating a process plant. It should be stressed that, despite the long experience of the industry in processing orange fruit and the large amount of research that has been done on the subject, all the secrets of orange juice have not yet been revealed. This subsection takes a look at the impact of raw materials, processing and bulk storage on the quality of orange juice according to Figure 4.1. Considerations involved in minimising quality degradation during processing are listed in Table 4.1. The effect of packaging and shelf storage on juice quality is discussed in Section 9.
4.1 Impact of processing on juice quality Orange juice is a complex product. Therefore a good understanding of the basic nature and properties of orange juice is needed for processing and packaging orange juice. In fact, to ensure that high product quality is maintained during juice processing, such understanding is indispensable. Section 4 as a whole looks at the principles of processing orange juice that have to be taken
46
4.1 Impact of processing on juice quality
Highly alkaline water may affect the acidity of the final product, and excessive solids and minerals will cause a brackish or metallic taste. Chlorine imparts water with a “pharmaceutical” taste and has a negative influence on juice colour and taste. Both iron and copper catalyse oxidation reactions which result in chemical changes. Microorganisms and organic debris contaminate juice, affect its taste and reduce product shelf life. However, the main spoilage organisms of juice products are not commonly found in water. Despite all the possible effects on juice quality, there are no regulatory standards specifying water quality for beverage production other than that it should fulfil the drinking water standards in the respective country. Read more about water treatment in subsection 7.3.
4.1.1 RAW MATERIALS Orange fruit
The quality of orange fruit is important for the characteristics of the final orange juice product. Since oranges are natural products, they vary significantly in flavour, vitamin C content and colour according to the variety of orange, the time of season when harvested and the region of the world where they are grown. A prerequisite for initial high juice quality is the use of whole, undamaged oranges with low microbial populations. Juice concentrate
Juice concentrate is the raw material for the juice packer. As the quality of reconstituted juice depends very much on the quality of concentrate used, it is essential that high quality concentrate with the desired Brix:acid ratio, colour and sinking pulp content is used. °Brix determines the volume of single-strength juice that can be reconstituted from a given volume of concentrate. The microbial condition of concentrate is another important factor because high microbial loads demand more intensive pasteurisation to achieve the required product stability. The maximum microbial load in concentrate should be specified by the concentrate producer.
4.1.2 PROCESSING
Processing steps to stabilise extracted orange juice with respect to enzyme and microbial activity are indispensable before concentration, bulk storage, packaging and distribution. One exception is perhaps for the small amount of freshly squeezed, unpasteurised single-strength orange juice which is distributed chilled and has a shelf life of up to 3 weeks, often shorter. Heat treatment with respect to time/temperature settings should be designed to minimise unwanted chemical and flavour changes in the product. Never theless it should still give an adequate safety margin concerning the inactivation of enzymes and spoilage microorganisms.
Water
Water must often be treated before it can be used for juice reconstitution. The degree of treatment depends on the water source. As regards reconstituted orange juice, the quality of water is critical with respect to the content of chlorine, metals, nitrates, salts, air, etc.
47
4.1 Impact of processing on juice quality
loss of nutritional value. It is generally agreed that the degradation of vitamin C in citrus juices can occur through both aerobic (depending on oxygen) and anaerobic (not depending on oxygen) reactions of nonenzymatic nature. Which one predominates depends on the temperature and availability of oxygen. During processing, the aerobic degradation of vitamin C predominates, whereas during orange juice storage both pathways must be taken into account. In the aerobic degradation of vitamin C, the presence of 1 mg oxygen corresponds theoretically to a loss of 11 mg vitamin C. This calculation is based on the reaction where vitamin C is oxidised to dehydroascorbic acid.
TABLE 4.1 PROCESSING CONSIDERATIONS AT THE FRUIT PROCESSOR - Choice of orange fruit. - Short residence time in the fruit bins before extraction to prevent deterioration of fruit. - Fruit washing and grading. - Fruit sizing. - Optimal extractor pressure and correct finisher settings to avoid unwanted (of ten bitter) compounds in fruit from entering the juice. - Evaporation using low temperature and short residence time to obtain high-quality concentrate.
AT THE JUICE PACKER - Preventing air contact during concentrate handling and reconstitution. - Water quality. - Short residence time after juice reconstitution and prior to pasteurisation to minimise microbial growth and vitamin C degradation. - The use of correct temperatures during pasteurisation and filling. - Package integrity. - Storage conditions.
AA + 1/2 O2
DHA + H2O
AA = ascorbic acid (vitamin C) DHA = dehydroascorbic acid
Oxygen is soluble in single-strength juice up to a level of approximately 8 mg/l, which corresponds to a potential loss of 88 mg vitamin C. Assuming an initial vitamin C content of about 450 mg/l, this corresponds to a 20 % loss in the nutritional quality attributed to vitamin C. Subsection 9.2.1 gives more information on how different storage conditions affect vitamin C degradation.
To a great extent the loss of quality during processing is similar to that encountered during packaging and shelf storage. Refer to Section 9, packaging and storage of orange juice, which complements the information presented in this section. Oxygen impact on vitamin C degradation
At the fruit processor, the loss of vitamin C (ascorbic acid) from orange fruit to frozen orange juice concentrate is generally negligible when the right processing conditions and short residence times before concentration and freezing are used. During reconstitution of the orange juice and further processing steps, the amount of oxygen present has an important impact on juice quality. Oxygen is a very reactive element which can induce several changes in the chemical composition of orange juice, the most dominant of which is the loss of vitamin C and consequent
Flavour changes
The desirable taste of freshly squeezed orange juice is easily affected by heat treatment and subsequent bulk storage. The juice may undergo several chemical reactions that can degrade the original volatile flavours of the juice. In addition, off-flavours can be formed mainly from compounds in the aqueous juice matrix. The Maillard reaction, a well-known reaction between sugars (or vitamin C) and amino acids, is an example of this.
48
4.1 Impact of processing on juice quality
Several potential off-flavour molecules have been identified in orange juice. Most of these compounds are formed during juice storage, although it takes a long time (several months) or storage at high temperature before any off-taste is noted, i.e. the compounds responsible for an off-taste are present in high enough concentration. PVG, 4-vinyl guaiacol, is an exception. This compound has been found in concentrations above its perception threshold in newly extracted and processed juice. It imparts an old fruit or rotten fruit aroma to the juice. PVG is formed from an odourless compound – ferrulic acid – normally present in juice. The concentration of free ferulic acid in juice has been shown to double after the first pasteurisation step, thereby greatly increasing the possibility of PVG forming. More about off-flavours is presented in subsection 9.2.3. When orange juice is concentrated in an evaporator, the volatile water-soluble and oil-soluble components that provide most of the characteristic orange flavour are removed. The process flavour (also known as “pumpout” flavour) obtained is a combination of the loss of volatile flavour and the cooked taste resulting from heat treatment. The impact of these unwanted changes can be compensated for by addition of flavour fractions at a later processing stage.
For long-term storage, the lower temperatures are used. Industry experience has shown that this temperature range is needed to avoid changes in colour and taste. At temperatures below –20 °C, concentrate can be stored for several years and still be of acceptable quality. If the pasteurisation of juice prior to concentration has not been carried out correctly, the residual enzyme activity can lead to gelation of the concentrate. Pectic substances in the juice form a gel which prevents the concentrate from being reconstituted to a juice of acceptable quality. See subsection 4.4.2.
enzymes are not completely “Ifinactivated, gelation of concentrate may occur
”
Not-from-concentrate juice, NFC
Two kinds of bulk storage are practised for NFC: • frozen (in 200 l drums at –18 °C or lower) • chilled (in large aseptic tanks or aseptic bagin-box containers at –1 to 1 °C) Both forms of storage give a shelf life of at least one year. This long shelf life is necessary since juice from fruit harvested at different times of the season is blended to obtain consistent quality yearround. Low-temperature storage is important; a temperature around 0 °C is low enough to avoid deterioration of the juice while still keeping the juice as a liquid. An advantage of aseptic NFC storage over frozen NFC is that the juice does not have to be thawed before final packaging. This avoids the use of crushing equipment and high energy input for quick thawing. At ambient temperature thawing takes several days and therefore product quality may deteriorate during this period due to microbial growth and flavour degradation.
4.1.3 IMPACT OF LONG-TERM BULK STORAGE
During bulk storage the product is kept under conditions that minimise changes in quality. This is of great importance since storage may be for a year or longer. Demands on the storage conditions depend on the orange juice product, FCOJ and NFC, and the intended storage time. Frozen concentrated orange juice, FCOJ
Orange juice concentrate is bulk-stored frozen at temperatures from –6 to –25 °C to avoid degradation of product quality. A temperature of –8 °C is often used during bulk transport.
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4.2 Air/oxygen in the product
4.2 Air/oxygen in the product
Temperature
Air consists mainly of the gases nitrogen and oxygen. These gases are soluble in orange juice to a certain degree, but if the juice contains more air than it can dissolve, free or dispersed air bubbles are formed. Air in the product can cause a number of problems for the juice packer, such as: • decreased product quality due to oxidation • foam formation in the deaerator • foam formation during filling, which leads to underfilling of retail packages • uneven distribution of floating cells in retail packages
Pressure
Sugar concentration
Fig. 4.2 The effect of temperature, pressure and sugar concentration on oxygen solubility.
Oxygen solubility
The solubility of oxygen is important since dissolved oxygen is more difficult to remove than dispersed oxygen. The solubility of oxygen and other gases in a liquid, i.e. the concentration of dissolved gas, depends on pressure, temperature and the concentration of soluble solids in the liquid (see Figures 4.2 and 4.3). Solubility decreases with: • increasing temperature • decreasing oxygen partial pressure • increasing concentration of soluble solids (sugars)
COMPOSITION OF AIR: Nitrogen N2 Oxygen O2 Other gases
Solubility of oxygen
78 % v/v 21 % v/v minor
It is therefore important to prevent air from entering juice during reconstitution and blending of concentrate. If the juice does contain air after reconstitution, it can be removed later in the process. Dispersed air can be decreased by letting the juice rest for half an hour in an open tank before pasteurisation. A deaerator can be used to further decrease the air content. A deaerator uses vacuum at ambient or elevated temperatures to remove dispersed and soluble gases from the juice. Nitrogen can be considered as an inert gas with regard to juice quality, whereas oxygen is very reactive and is involved in many reactions that impair quality. It is therefore essential to remove oxygen from juice. The deaeration efficiency is determined by measuring oxygen concentration in the product before and after deaeration.
The measured amount of oxygen in orange juice can sometimes be higher than its theoretical solubility values. This can be explained by the phenomena whereby free oxygen adsorbs as gas bubbles to pulp particles in the juice. When solubility decreases due to increased temperature and/or reduced pressure, the gas released does not leave the product but stays as gas bubbles on the surface of fruit cell particles. This adsorption phenomena appears mainly on large particles in the form of added floating cells, but not on the smaller sinking pulp particles.
50
4.2 Air/oxygen in the product
14.00
4.2.1 SOURCES OF AIR/OXYGEN 100 kPa, atmospheric pressure
Oxygen (mg/litre)
12.00 10.00 8.00 6.00 4.00
20 kPa
2.00 0.00 0
10
20
30
40
50
60
70
Temperature (°C)
Fig. 4.3 Solubility of oxygen in water as a function of temperature at two different pressures.
Oxidation
The main reason for deaerating juice is to reduce its oxygen concentration. Oxygen is very reactive and promotes many of the reactions that take place in juice during processing and storage which lead to quality degradation. The most important reaction is the oxidation of vitamin C, which leads to loss of nutritional quality (see subsections 4.1 and 9.2). Considering that many countries have regulations that define the minimum level of vitamin C in products at the end of their shelf life, and as long shelf life (3 to 9 months) is a desired benefit, the importance of maintaining the vitamin C content of juice is readily understood. Other significant parameters like colour are also affected by oxidation (see subsection 9.2).
At the fruit processor, juice is in contact with air during extraction and finishing. Deaeration is essential in the production of NFC for bulk storage, since a high oxygen level will decrease its vitamin C level significantly. Oxygen is less of a problem in the production of concentrate because gases are removed in the evaporator. However, if concentrate is mishandled, a large amount of dispersed air may enter the concentrate. The various steps of reconstituting orange juice from concentrate present a number of entry points for oxygen and air. Nevertheless, optimising the first process step to avoid air entry minimises problems later in the process. Steps where particular care is needed are: handling of juice concentrate, handling of water, addition of floating cells, flow in pumps and pipes, blending and reconstitution (Figure 4.4). Concentrate
Concentrate can be a source of gases. Although the solubility of oxygen in orange juice concentrate is low due to the high concentration of soluble solids, the high viscosity of concentrate makes it difficult for free gas bubbles to rise to the surface. Therefore careful procedures are important during all handling steps involved with concentrate, including its transport, transfer and blending.
Concentrate
Water
Blending/ Agitation
Pumps & pipes
Floating cells
Fig. 4.4 Sources of oxygen/air entry during orange juice reconstitution.
51
4.2 Air/oxygen in the product
Blending tanks
Deaeration
Pasteurisation
Filling
Storage
Fig. 4.5 Process steps where high oxygen/air concentrations can cause problems.
Water
Tanks
Water for reconstitution is often a source of high levels of dissolved oxygen. The solubility of oxygen in cold water is about 9 mg per litre (at 20 °C). Deaeration of water before reconstitution of juice minimises dissolved oxygen. It can also eliminate the need to deaerate reconstituted juice. During certain water treatments, the carbon dioxide concentration builds up to levels that cause problems with foaming during the deaeration of juice containing floating cells.
Tank inlets should be designed to prevent air entry and foaming when the tank is filled. Juice should not be left in blending tanks for long periods before deaeration and pasteurisation, since this may lead to impaired quality due to microbial growth and vitamin C loss. Sometimes tanks are blanketed with nitrogen to prevent oxygen entry, especially in buffer tanks containing deaerated juice. 4.2.2 PROBLEMS CAUSED BY AIR/OXYGEN IN THE PRODUCT
Floating pulp
If air gains entry during the initial reconstitution steps, it can cause problems later in the process. See Figure 4.5.
Addition of floating pulp to juice often increases its gas content. Frozen pulp contains a lot of air, both as air bubbles adsorbed to the surface of pulp particles and as free bubbles which are not released due to the high viscosity of concentrated pulp. Moreover, the agitation required to blend pulp with juice and keep the mixture homogenous in the tank increases the risks of additional gas entry. Due to gas bubbles adsorbed to cell particles, the measured oxygen content can exceed 9 ppm/litre at 20 °C.
Blending tank
Gas bubbles adsorbed to floating pulp reduce their density and make them float to the top of juice. This makes it difficult to maintain even distribution of floating pulp in the blending and balance tanks. Deaerator
Dissolved and dispersed gases are removed in the deaerator. Problems with foaming can occur if the incoming product contains high concentrations of undissolved gas. When juice goes from a higher pressure (in the pipes) to a lower pressure (in the deaerator), gas solubility decreases and bubbles of free gas form in the juice and build up foam. The foam formed in the deaerator and filling machine consists mainly of gas which is separated by very thin layers of liquid film. Some foam in the deaerator does not affect its performance, but if the deaerator is filled with foam deaeration becomes insufficient. This problem is mainly found with juices containing floating pulp or a lot of dispersed gas.
Pumps and pipes
Bad piping design and pumps that are not airtight can be responsible for air entry. Blending/agitation
It is important to use the right blending and reconstitution techniques. Blending in tanks should be done with low-speed agitators, and the juice should cover the agitator. In some cases, blending is carried out under a blanket of nitrogen to prevent oxygen entering the product. Using an in-line blending technique minimises oxygen ingress during reconstitution.
52
4.2 Air/oxygen in the product
Henry’s law states that the equilibrium concentration XA of gas A in solution is proportional to the partial pressure of gas A in the vapour phase. In order to remove dissolved oxygen (decrease XA in Henry’s law) a driving force must be applied. This can be done either by: • reducing the oxygen partial pressure (PA) above the liquid surface; • increasing the temperature (T). This will increase Henry’s constant [H(T)].
Pasteurisation
Ineffective pasteurisation can occur if juice contains very high concentrations of dispersed gas (which may lead to reduced residence time or inconsistent heating). Filling
Problems with foam in filling machines may occur for the same reasons as with deaerators, i.e. foam is formed when the pressure is suddenly released in the filling nozzle. Foaming causes decreased filling efficiency that can lead to: • product losses • incorrect amounts of juice in packages
A combination of these two alternatives is often used during deaeration. The partial pressure (PA) is reduced by either using a vacuum (the total pressure becomes very low) or by replacing oxygen in the gas phase with another gas. Dispersed oxygen bubbles in juice (without added floating cells) can be removed by leaving the juice in an open tank. The gas bubbles, which have a lower density than the juice, will rise to the top and gradually leave the juice with time. This process can be accelerated by creating a vacuum above the juice. However, it is still a relatively slow process. Dissolved oxygen and oxygen bubbles adsorbed to floating pulp are much more difficult to remove by such a tank process. To increase the efficiency of deaeration, it must be made difficult for the oxygen to remain in the juice, e.g. by decreasing its solubility. This can be done by: • increasing the temperature • decreasing the pressure
If the juice contains floating pulp, gas in the juice can cause poor distribution of particles in the packages (see blending tank). Storage
Oxygen takes part in many reactions that impair the quality of juice during storage. These reactions include changes in colour and taste, and degradation of vitamin C. It is therefore crucial to protect the juice against oxygen during storage. The need for protection depends on the period the juice will be stored for and at what temperature. (See Section 9.) 4.2.3 PRINCIPLES OF DEAERATION
The concentration of dissolved gases in a liquid follows physical laws. One of the more important relationships is the one defined by the scientist Sir William Henry (1775–1836). A gas which is dissolved in a liquid is in equilibrium with the gas above the liquid surface. This equilibrium is given by Henry’s law.
XA=
It is important for the juice to have sufficient residence time in the deaerator to allow the gas to leave the juice. By turning the juice into thin layers of liquid, the distance the gas has to diffuse from the liquid phase to the gas phase is minimised, thereby producing a high rate at which the gas leaves the juice.
PA H(T)
XA =
concentration of gas A in the liquid phase (mole fraction). PA = partial pressure of gas A in the vapour phase (Pa). H(T) = Henry’s constant. It is a function of temperature and depends on the liquid (Pa/mole fraction).
53
4.3 Microbiology of orange juice
There are several types of stripping system. In one type, the liquid and the gas meet in countercurrent flow as they pass through a packed column. In a another, the liquid is sprayed into a room filled with gas, or the gas is sprayed into the liquid stream before the deaerator vessel.
Deaerators
Methods of removing oxygen include vacuum deaeration and counter-current flushing with an inert gas. Existing methods of deaeration do not remove all oxygen from juice. Nevertheless, vacuum flash deaeration reduces residual oxygen to levels that no longer have a significant impact on juice quality.
4.3 Microbiology of orange juice
Vacuum deaerator
In a continuous vacuum deaerator, the gases are removed from a thin film of juice over a large area at a raised temperature and/or at a underpressure. A thin layer of juice can be achieved by: • spraying the juice through a nozzle • spreading the juice by centrifugation • distributing the juice over surface packing
4.3.1 RELEVANT MICROORGANISMS IN ORANGE JUICE
Although several microorganisms have been isolated from orange juice, few of them cause spoilage. The high acidity (low pH) of juice limits the types of microorganism that can grow in the juice. Juice spoilage is caused by microorganisms that are able to multiply in juice during its processing and storage (see Table 4.2.) The growth of microorganisms in orange juice is characterised by fermentation and/or the production of off-flavours that spoil the product. Fermentation may lead to gas formation, which, in turn, results in blown packages.
When juice is sprayed through a nozzle or run over packing and/or trays, a large surface area is created for release of oxygen from the liquid to the vapour phase. Dissolved oxygen has then only a short distance to diffuse to the liquid surface. The finer the nozzle or the more packing/trays, the quicker (and therefore often better) deaeration at a given temperature. However, there are practical and cost limitations. During vacuum flash deaeration, usually about 1 % of the liquid is vaporised. As the vapour contains some volatile flavour components, it has to be condensed back into the juice. This can be done either by an internal or an external condenser that chills the vapour back to a liquid state. In both cases, the temperature of the cooling water in the condenser and the vacuum applied will determine the amount of flavour components condensed.
TABLE 4.2 THE PREDOMINANT MICROORGANISMS IN ORANGE JUICE Acid-tolerant bacteria Yeasts Moulds
Acid-tolerant bacteria
Lactic acid bacteria belonging to the genera Lactobacillus and Leuconostoc are the most common acid-tolerant bacteria that cause spoilage of orange juice (see Figure 4.6). Spoilage is characterised by a “buttery” or “buttermilk-like” flavour resulting from the formation of diacetyl during bacterial growth. Leuconostoc and many species of Lactobacillus also produce large amounts of CO2.
Gas stripping
In the gas-stripping type of deaerator, the partial pressure of oxygen in the vapour phase is reduced to almost zero by displacing the oxygen with another gas, e.g. nitrogen (N2) or carbon dioxide (CO2). By removing the oxygen in the vapour phase above the liquid, the oxygen in the juice is forced out from the juice into the vapour phase. This process does not reduce the total gas content of the juice but replaces oxygen with another gas.
54
4.3 Microbiology of orange juice
The optimal growth temperature for most yeasts is 20–30 °C. They are more tolerant of cold temperatures, high osmotic pressure and lack of nutrients than bacteria or moulds. Species of yeasts can easily survive in citrus concentrates of 58 to 65 °Brix and in frozen juices.
are the most common “Yeasts type of spoilage organism ” Saccharomyces cerevisiae, Rhodotorula spp and Zygosaccharomyces spp are the most common yeasts present in juice. Saccharomyces cerevisiae is most commonly associated with the spoilage of pasteurised citrus juices. The presence of Rhodotorula may be indicative of poor postpasteurisation hygiene. Zygosaccharomyces is an osmophilic yeast, which means that it can survive the high osmotic pressures and low water activity of concentrated orange juice. It is frequently associated with spoilage of concentrates.
Fig. 4.6 Different shapes of lactic acid bacteria.
Most lactic acid bacteria grow best in orange juice at temperatures between 20 and 37 °C. Their rate of growth is greatly reduced above or below these temperatures. Growth is very slow at 4 °C in single-strength juice. These bacteria are sensitive to heat and high osmotic pressure (high juice concentration); no growth is observed in juice above 45 °Brix. Lactic acid bacteria pose the biggest problem during the processing steps prior to concentration. After extraction, the juice has to be refrigerated or heat-treated as soon as possible to prevent the build-up of large populations of these bacteria. It is also important for fruit processors to maintain an effective programme of sanitation. The main species of lactic acid bacteria causing spoilage are Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc mesenteroides and Leuconostoc dextranicum. Yeasts
Fig. 4.7 Yeasts showing budding reproduction.
Yeasts (see Figure 4.7) are the most common type of spoilage organism in both single-strength and concentrated orange juice. Spoilage of orange juice by yeasts typically results from an alcoholic fermentation which leads to off-flavours and CO2 production. Yeasts not capable of alcoholic fermentation may cause turbidity, flocculation and clumping in juice.
55
4.3 Microbiology of orange juice
Some moulds that have been isolated from orange juice are: Aureobasidium pullulans, Aspergillus niger, Botrytis spp, Fusarium spp, Geotrichum spp, Mucor spp, Aspergillus fumigatus, Cladosporium spp and Penicillium spp.
Fig. 4.8 Example of mould structure.
Pathogenic microorganisms
The presence of pathogenic microorganisms in orange juice is rare. The low pH of juice inhibits growth of pathogens, but long-term survival of some pathogens in refrigerated orange juice is possible. Outbreaks of disease, particularly salmonellosis, traced back to orange juice have occurred as a result of consuming unpasteurised orange juice, or due to reconstituted juice becoming contaminated before serving. Diseases attributed to orange juice are mainly caused by incorrect product handling and can be prevented by carrying out approved sanitary procedures, pasteurising the juice, and by preventing product contamination after pasteurisation.
Moulds
Moulds form colonies of aerial mycelia on the surface of juice, and flocculation or floating mycelia within juice (see Figure 4.8). They can grow under a wide variety of conditions. In general, moulds grow well in acid media and require abundant oxygen. Moulds that grow in orange juice are generally sensitive to heat treatment and are thus easily destroyed by pasteurisation. Compared with yeasts and bacteria, moulds have only infrequently been associated with spoilage of orange juice. This is because of their aerobic (oxygen-dependent) nature and slow growth rates. However, with the advent of longterm chilled storage of single-strength juice and extended shelf life of juice in nonaseptic cartons with oxygen barriers, mould growth in citrus juice has become a more important issue. Moulds may give rise to concern during juice extraction when fruit-handling and juice room equipment is not kept in hygienic condition. When the correct approach to sanitation is neglected, moulds colonise the surfaces of conveyor belts, fruit bins, extractors and other equipment. These conditions promote the contamination of juice or the surfaces of containers.
Spore-forming microorganisms
Most bacterial spores cannot grow in fruit juices with a pH below 4.5. Though very rare, thermoresistant acidophilic bacteria have been isolated from shelf-stable juices. In 1992 these strains were classified in a new genus called Alicyclobacillus. Microorganisms belonging to this genus have a preference for thermophilic temperatures with an optimum temperature around 45 °C, and they will most likely not grow below 20 °C. The most likely source of contamination of fruit juices is fruit contaminated with soil during harvesting. Such contamination is introduced into the manufacturing process through unwashed or poorly washed fruit. A spoilage characteristic of this type of bacteria has been described as an off-flavour like “disinfectant” or guaiacol. No gas production has been observed.
56
4.3 Microbiology of orange juice
Not-from-concentrate juice, NFC
4.3.2 MICROFLORA OF DIFFERENT TYPES OF ORANGE JUICE
After pasteurisation, NFC is either filled directly into consumer packages or, more often, stored in bulk for a period of time under chilled aseptic or frozen conditions. Generally, microbial spoilage of pasteurised single-strength juice sold chilled under nonaseptic conditions is due to fermentative yeasts. The most common spoilage organism in this product is Saccharomyces cerevisiae, although other yeasts have occasionally been isolated as well. The microflora of NFC strongly depends on juice storage temperature. At temperatures ≤7 °C yeasts are the predominant flora responsible for spoilage, whereas at ≥10 °C lactic acid bacteria outgrow the yeasts and become the main spoilage organisms. The main species present are lactic acid bacteria, such as Lactobacillus spp, Leuconostoc spp, and yeasts like Zygosaccharomyces spp and Saccharomyces cerevisiae.
The microflora of different orange juice products can vary widely according to the state of raw fruit, and juice processing and storage conditions. Frozen concentrated orange juice
FCOJ is not aseptic or commercially sterile. It can contain abundant microflora of wide diversity including yeasts, moulds and bacteria. However, frozen orange juice concentrate does not have any significant microbial problems because it is stored frozen. Concentrated orange juice quite often has a total microbial population around 100 to 1,000 organisms/ml. In general, an acceptable microbial quality of concentrate is a total viable count lower than 1,000/ml; for yeasts in the range of 100/ml, and for moulds lower than 10/ml. When concentrate is exposed to temperatures above freezing point, osmophilic yeasts like Zygosaccharomyces spp are the primary spoilage organisms.
Freshly squeezed orange juice – unpasteurised
The total number of microorganisms in this product varies throughout the season and is strongly dependent on the condition of the fruit and sanitation of the processing equipment. In general, higher counts are observed with mature oranges that have a higher ratio (Brix:acid). Much higher counts are observed with unsound fruit. The hygienic condition of the processing plant will also influence the number of microorganisms present in juice. In general, freshly squeezed orange juice has a total microbial count ranging from 1,000 to 10,000 organisms/ml. However, this number may be as high as 32,000,000 organisms/ ml in juice extracted from poor-quality oranges in processing plants with bad sanitation.
Reconstituted orange juice from concentrate
As yeasts represent the dominant microflora of any consequence in concentrate, it is most likely that they will remain so in juice reconstituted from concentrate. Nevertheless, if reconstitution is not carried out under appropriate sanitary conditions, the type and number of microorganisms in the end product will increase. Microorganisms normally present in the sur rounding air and water, and on equipment, can contaminate juice. Juice should not be held in tanks for long periods of time before pasteurisation. Whenever concentrate is reconstituted to single-strength juice, microorganisms that were dormant in the concentrate are suddenly provided with the conditions that allow them to grow rapidly. After dilution of concentrate but prior to pasteurisation, juice is held in tanks. These require proper cleaning procedures to prevent them from becoming a source of contamination.
57
4.3 Microbiology of orange juice
Juice not from concentrate
Pasteurisation
Chilled/ frozen storage
Juice extraction
Juice from concentrate
Cold filling
Chilled distribution
Aseptic filling
Ambient distribution
Pasteurisation
Pasteurisation/ concentration
Reconstitution Frozen storage
Fig. 4.9 Orange juice pasteurisation steps.
The low pH of juice and a rapid juice reconstitution process usually suffice to prevent the build-up of large microbial populations in juice. Furthermore, as reconstituted juice is pasteurised before packaging, microorganisms of concern will be destroyed. However, if a plant has poor cleaning routines and reconstituted juice is held in tanks for a long time prior to pasteurisation, high populations of microorganisms can become established. This will demand higher pasteurisation temperatures to completely destroy the microorganisms. In fruit processing plants, microbial contamination is controlled by three different levels of cleaning: • Frequent cleaning during everyday production which is necessary to maintain the hygienic appearance of equipment. • Intermittent-type cleaning while plant is in operation, or cleaning parts of the plant temporarily taken out of production in order to clean them properly. • General cleanup of the plant which occurs when the plant is completely shut down.
4.3.3 INFLUENCE OF RAW MATERIALS Fresh fruit
Microorganisms found in nature will enter the processing plant via fruit, soil, animals and people. Their number will vary depending on harvesting method as well as handling on the way from the groves to the processing plant. Out of the large variety of microorganisms, only those species capable of growing during the production of orange juice are of prime concern. These are lactic acid bacteria, yeasts and moulds. Fruit grading and washing
There is a correlation between the percentage of defective fruit entering a processing plant and the contamination of extracted juice. To minimise microbial contamination within a plant, fruit must be carefully graded and washed effectively. In some cases fruit is treated with detergent to minimise surface microorganisms. All unsound fruit should be removed. Washing is usually done with (chlorinated) water sprays located at strategic points on conveyor belts and elevators. The sprays must cover the entire width of the belt completely, otherwise microorganisms will accumulate at the edges of the belt. Washing efficiency has a direct bearing on the microbial population of extracted juice.
Flushing with chlorinated water is generally performed periodically to control microbial contamination while the plant is in operation. Floors should not be cleaned during operation of the production line because this can spread microorganisms. Cleaning-in-place (CIP) systems that greatly improve the efficiency of cleaning are now generally used by processing and packaging plants. See also subsection 7.9.
4.3.4 SANITATION
Effective cleaning procedures are essential in controlling microbial contamination in production of orange juice concentrate, as well as during reconstitution of concentrate to produce singlestrength orange juice.
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4.4 Pasteurisation
4.4 Pasteurisation
4.4.2 INACTIVATION OF ENZYMES
Cloud loss of single-strength juice and gelation in concentrate are mainly caused by pectin methyl esterase, which is present naturally in fruit. PME is mainly active in the temperature range from 5 to 65 °C and shows maximum activity at 60 °C. Above 60 °C its activity gradually decreases. The activity of the enzyme at temperatures below 5 °C is low, but it is still enough to cause cloud loss in single-strength orange juice. Even at a temperature as low as –18 °C the reaction rate is high enough to cause gelation of concentrates during storage.
4.4.1 PURPOSE OF PASTEURISATION
The purpose of pasteurisation is to make the juice product stable during subsequent processing and storage. Pasteurisation of orange juice is necessary for destroying the microorganisms capable of growing during storage, and for inactivating enzymes to prevent cloud loss. Enzymes are proteins that catalyse biological reactions. They are necessary for the growth of all living matter. Orange juice is pasteurised at least twice before it reaches the consumer (except for a small amount of NFC that is filled directly into consumer packages). The first pasteurisation occurs immediately after extraction prior to bulk storage, and the second pasteurisation occurs before packaging (see Figure 4.9). The first pasteurisation is necessary to completely inactivate the enzyme pectin methyl esterase (PME), also known as pectin esterase (PE), which will otherwise cause cloud loss of single-strength juice and gelation of concentrate during storage. Microorganisms of commercial interest are also killed by this process. The second pasteurisation destroys any microorganisms that may have contaminated juice after the first pasteurisation step and survived bulk storage, as well as those which may have contaminated juice during its reconstitution from concentrate.
A given enzyme will only split cer tain molecules, and only at certain bonds.
FACTS ABOUT ENZYMES Enzymes are proteins produced by living organisms specialised in catalysing biological reactions. They are therefore sometimes called biocatalysts. Enzyme action is specific; each type of enzyme catalyses only one type of reaction. The action of an enzyme is also strongly influenced by temperature and pH. The basic function of an enzyme that breaks down a larger molecule into smaller ones is illustrated in Figure 4.10. The enzymes in orange juice come from the fruit itself. They are firmly associated with the cell wall fractions and therefore are mainly derived from parts of orange like peel, rag and juice sac tissue (pulp). Enzymes are released from the fruit solid phase (membranes) into the liquid phase (juice) during the extraction process.
The enzyme fits into a particular spot in the molecule chain, where it weakens the bond.
Fig. 4.10 The basic function of an enzyme.
59
The molecule splits. The enzyme is now free to attack and split another molecule in the same way.
4.4 Pasteurisation
• Among orange varieties from Brazil (Pera Rio, Pera Coroa, Natal and Valencia), PME in Valencia and Pera Rio juice had the highest heat resistance, requiring 2 min at 90 °C for complete inactivation, whereas PME in Pera Coroa and Natal varieties was inactivated after 1.5 min at 90 °C. • Juice with higher pH requires a more intensive heat treatment to inactivate PME than juice with lower pH. The influence of pH on thermal inactivation of PME is dependent on fruit variety. Orange juice from the Pineapple variety showed the highest sensitivity to pH changes, followed by Valencia. • As PME is associated with cell wall materials, a higher heat load is required in juices with higher pulp content. An increase of pulp content from 5 to 10 % increases by about 2.5 times the time required at a given temperature to inactivate PME.
1000
D value (sec)
100
10
1 60
70
80
90
100
110
Temperature (°C)
Fig. 4.11 Decimal reduction time (D value) for PME in Valencia orange juice at pH = 4.1 and with 12 % pulp content.
Cloud loss
The most common reason for cloud loss or gelation in orange juice is the enzymatic breakdown of pectin molecules in the juice. Pectin is a complex organic substance (consisting mainly of partially methylated sugar units) that exhibit important properties, such as the ability to form emulsions and to increase liquid viscosity. In single-strength orange juice, pectin is one important constituent of the cloud. The cloud of orange juice contributes to its visual appearance (opacity) and viscosity. Viscosity is essential for good juice “mouthfeel”. The enzyme breaks down pectin by removing methyl groups from the sugar units. The resulting molecule reacts with calcium (naturally present in the juice) to create bridges between the sugar units, see Figure 4.12. The insoluble molecule formed is called calcium pectate. In single-strength juice, calcium pectate settles to the bottom of the package. This causes separation of the juice into a clear upper phase and a lower sediment phase. This separation is referred to as cloud loss. In orange juice concentrate, calcium pectate forms gel-like lumps due to the high sugar and acid content. This gelation makes it impossible to reconstitute to orange juice of good quality.
In order to prevent cloud loss or gelation during processing and storage of orange juice, it is necessary to inactivate PME. Although several methods have been tested, pasteurisation is the only process used industrially to inactivate the enzyme. The time-temperature conditions to inactivate PME are dependent on : • juice pH • juice pulp content • fruit variety/maturity From the literature it is known that: • Among the varieties of oranges from Florida (Valencia, Pineapple and Hamlin), the heat stability of PME was highest in juice from Valencia oranges, and similar in juice from Pineapple and Hamlin oranges. Figure 4.11 shows the decimal reduction time for PME in Valencia oranges grown in Florida. The D value correspond to 90 % enzyme inactivation. A heat load corresponding to 2–3 D values is generally sufficient for inactivation of the enzyme.
60
4.4 Pasteurisation
Secondary pasteurisation
The second pasteurisation, carried out prior to juice packaging, involves NFC after bulk storage or juice reconstituted from concentrate. It is for microbial destruction rather than inactivation of enzymes. Since microorganisms are less heat resistant than enzymes, the second pasteurisation may be carried out at a lower temperature than the first pasteurisation. The required time-temperature combination for the second pasteurisation will depend on the total number of microorganisms in the juice to the pasteuriser. This population of microorganisms depends on the initial number in the concentrate, residence time in tanks before pasteurisation and the standard of plant sanitation.
O O-CH3 C
Pectin methyl esterase Cacium (Ca2+) Pectin bridges methylesterase -
O O CH3OH C
Fig. 4.12 The action of the enzyme pectin methyl esterase (PME).
4.4.3 INACTIVATION OF MICROORGANISMS
The heat-resistance of microorganisms is affected by factors like pH, water activity and oxygen. The reduction of microorganisms is more efficient under conditions not favourable for their growth. In general, moulds are less resistant to heat than yeasts and yeasts less resistant to heat than bacteria. The yeast Saccharomyces cerevisiae is the most common spoilage organism in citrus juices. It can form ascospores that are much more heat-resistant than its vegetative cells.
FACTS ABOUT THERMAL PROCESSING The use of heat for a given period of time is a method of food preservation used to destroy microorganisms, enzymes and heat-labile toxins. Pasteurisation and sterilisation are two types of thermal processing. Sterilisation destroys all living microorganisms including microbial spores, whereas pasteurisation kills the majority of vegetative microorganisms, particularly pathogenic bacteria, but has little or no effect on bacterial spores. Pasteurisation is generally adequate heat treatment for highacid juice foods.
4.4.4 TIME-TEMPERATURE CONDITIONS FOR PASTEURISATION
Thermal resistance of microorganisms is tradi tionally expressed in terms of D values and z values. These are defined as follows:
In orange juice, PME is more heat-resistant than the microorganisms commonly present in orange juice. This means that a more intensive time-temperature treatment is necessary to inactivate the enzyme than to destroy microorganisms.
D value: D value, or decimal reduction time, is the time required at a given temperature to decrease the population of a specified microorganism by 90 % or one log cycle. For example, D80 = 1 min means that it takes 1 minute at 80 °C to destroy 90 % (or one logarithmic reduction) of the specified microorganism.
Primary pasteurisation
Orange juice should be pasteurised to inactivate PME as soon as possible after extraction. It is pasteurised above 95–98 °C for 10–30 sec. This can be done as a separate step or as a first step in the evaporator.
z value: This is the change in temperature needed to alter the D value by one log cycle. For example, if an organism has a z = 5 °C and a D80 °C = 1 min, the D85 °C = 0.1 min and the D75 °C = 10 min.
61
4.4 Pasteurisation
1000
Sac. cerevisiae
Pectin methyl esterase
Ascospores Time (sec)
100
Vegetative cells
10
1 50
60
70
80
90
100
110
120
Temperature (°C)
Fig. 4.13 Theoretical thermal destruction curves of pectin methyl esterase, ascospores and vegetative cells of Saccharomyces cerevisae in orange juice.
Figure 4.13 shows the theoretical thermal destruction curves of pectin methyl esterase, and of ascospores and vegetative cells of Sac. cerevisae in orange juice. All temperature/time combinations to the right of the ascospore curve are sufficient for 10 decimal reductions or more. The blue square shows the time/temperature combinations used mainly by the industry today. Since microorganisms grow much slower at chilled than at ambient temperatures, chilled juice can be sold as a nonaseptic product, i.e. nonaseptic filling and packaging can be used. However, the pasteurisation step must ensure that microorganisms in the juice will not spoil it during its intended shelf life.
intensive time-temperature “More treatment is necessary to inactivate
Temperatures from 80 °C up to 95 °C for 15–30 sec. are commonly used by the industry for the second pasteurisation of orange juice reconstituted from concentrate and intended for storage at ambient temperature. However, the industry is now showing an increasing interest in lowering the pasteurisation temperature and/or holding time. As already mentioned, Saccharomyces cerevisiae is the most common spoilage agent in orange juice. This species of yeast produces ascospores, a more resistant form of yeast cell. Based on the heat-resistance of this microorganism, (D60 = 3–19 min), a heat treatment of 75–80 °C for 15–20 seconds will be adequate to sufficiently reduce the microbial population (second pasteurisation) provided that the raw material is of good quality. When aseptically packed, this product can be stored under ambient conditions.
the enzyme PME than to destroy microorganisms
”
62
5
Fruit processing
In section 5 you will read about: • The production steps in a processing plant. • Fruit delivery and what is done at the fruit reception area to prepare oranges for juice extraction. • How the maximum amount of juice is squeezed from fruit and the two principal extractor types. • Removing pulp by clarification so that juice can be evaporated to concentrate or processed to single-strength juice.
• NFC production including heat treatment and bulk storage. • Concentrate production and the need for efficient evaporators. • The recovery of peel oil. How winterisation makes wax drop out. • The production of animal feed from waste streams. • Pulp production and the many uses of pulp. • Washing of pulp to recover valuable solids.
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5. Fruit processing
Pulpy juice
Fruit unloading
Grading
Juice extractor
Storage bins
Sizer
Washer
Grading
Concentrate
Finisher
Centrifuges
Concentrate cooler
Pasteuriser
Frozen storage tanks
Evaporator
Pulpy juice
NFC
Pasteuriser
Refrigerated aseptic storage
Oil emulsion
Pulp
Frozen drum storage Defect removal
Finisher
Pasteuriser
Finisher
Wet peel, rag, seeds
Peel oil
Concentrator
Polisher
Winterisation storage
Frozen drum storage
Animal feed
Presses
Drier
Silo
Fig 5.1 Flow chart showing typical processing steps found in an orange processing plant.
A box of oranges is defined as containing 40.8 kg (90 lb) of fruit. In Florida, the small/ medium-size plants typically process 5–10 million boxes (200–400,000 tonnes) per season, the large plants up to 25 million boxes. Most Brazilian citrus plants have much higher capacity. The world’s largest orange juice plant, Citrosuco at Matao, Brazil, can take in 60 million boxes (2.4 million tonnes) of fruit during a season. In most other orange-growing regions, citrus processing plants are considerably smaller than those in Florida and Brazil. Typical orange processing steps are shown in Figure 5.1.
5.1 Processing plant overview Orange processing plants are located in the vicinity of the fruit growing area. Fruit should be processed as soon as possible after harvesting because fruit deteriorates quickly at the high temperatures found in citrus-growing areas. Orange products, on the other hand, are produced in a form that allows them to be stored for extended periods and shipped over long distances. In the orange industry, the basic unit of reporting crop and plant intake is commonly the fruit box.
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5.1 Processing plant overview
Fruit reception
Not-from-concentrate juice (NFC) production
Fruit is delivered in trucks which discharge their loads at the fruit reception area. The fruit may be prewashed to get rid of immediate surface dirt and pesticide residue before any leaves and stems still attached to the fruit are removed. Then follows pregrading by manual inspection to remove any unsuitable fruit. Sound fruit is conveyed to storage bins. Damaged fruit goes directly to the feed mill.
Instead of concentrate production, juice may be processed at single strength as an NFC product. Clarified juice is pasteurised before storage. Deoiling may be required to reduce oil levels in the juice, and deaeration to remove oxygen is part of good practice. Since the product is consumed year-round but production is seasonal, NFC may be stored for up to one year. It is stored in bulk either frozen or under aseptic conditions.
Extraction
Extraction involves squeezing or reaming juice out of either whole or halved oranges by means of mechanical pressure. After final washing and inspection, the fruit is separated according to size into different streams or lanes. Individual oranges are directed to the most suitable extractor in order to achieve optimum juice yield. As the extraction operation determines juice yield and quality, the correct setting of extractor operating conditions is very important.
Pulp production
For pulp recovery, pulpy juice from the extractor is passed through a system that removes defects where undesirable pulp components, such as seed and rag, are removed. The clean pulp stream is then concentrated in a primary finisher. After heat treatment, the pulp slurry is typically concentrated further before being sent to frozen storage. Pulp wash
If the pulp fraction is not recovered for commercial sale, pulp from the final juice finishers and clarifiers can be washed with water to recover juice solubles. This stream is called pulp wash and may, legislation permitting, be blended with juice before concentration.
Clarification
After extraction, the pulpy juice (about 50 % of the fruit) is clarified by primary finishers which separate juice from pulp. The finishing process is a mechanical separation method based on sieving. The juice stream is further clarified by centrifugation. The pulp stream, containing pieces of ruptured juice sacs and segment walls, may then go to pulp recovery or to pulp washing.
Peel oil recovery
Recovered peel oil represents some 0.3 % of the fruit intake. The emulsion of oil and water coming from the extractor section is clarified by centrifugation in two steps. The purified oil contains dissolved waxes which are removed by winterisation (refrigeration) of the oil for a certain time.
Frozen concentrated orange juice (FCOJ) production
From the buffer/blending tanks and after clarification, juice goes to the evaporator. Within the evaporator circuit, the juice is first pre-heated and held at pasteurisation temperature. It then passes through the evaporation stages of the process where it is concentrated up to 66 °Brix. During the evaporation process, volatile flavour components flash off and can be recovered in an essence recovery unit. Juice concentrate is cooled and blended with other production batches as required to level out fluctuations in quality. It then goes to frozen storage in tanks or drums as FCOJ, sometimes for several years.
Feed mill
It is economically feasible to include a feed mill operation in larger processing plants. Rejected fruit from grading, peel and rag from extraction, and washed pulp and other solid waste are sent to the feed mill where it is dried and pelletised for animal feed. Smaller plants usually truck their solid waste to a plant with a feed mill or dispose of it in other ways, such as landfill.
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5.2 Orange juice production steps
5.2 Orange juice production steps
Picking of fruit
All production steps for orange juice, from orange fruit to packaged product, are shown in the block diagram Figure 5.2. The steps carried out in the fruit processing plant as highlighted in the figure are discussed in more detail.
Transport
Fruit reception
Main products
By-products
Oil emulsion
Juice extraction
Peel oil recovery Peel, rag, seed
Feed mill Pulpy juice
Pulp production
Pulpy juice
Pulp
Clarification
Pulp wash production
Essence recovery
Not from concentrate juice production
Concentrate pr production
Essence
Fig. 5.2 Production steps for orange juice. Bulk transport
Reprocessing
Packaging
Distribution
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5.3 Fruit reception
Truck unloading
Prewash
Destemming
Pregrade
Sampling
Final grading
Final fruit wash
Surge bin
Fruit storage
Fig. 5.3 Processing flow for fruit reception. Fruit storage
5.3 Fruit reception
The pregraded fruit is stored in bins specially designed with inclined multilevel internal baffles. These distribute the fruit evenly in the bin to prevent too much weight pressing on fruit. The procedure of holding the fruit in storage bins in order to reduce juice acidity and increase the final juice ratio needs to be applied with care, because passing fruit through bins usually reduces the final juice yield compared with direct processing. Besides the main function of storing fruit with different characteristics to provide processing options and the desired juice quality, correct management of stored fruit also make it possible to avoid very wide fluctuations in the Brix: acid ratio of raw juice. Such fluctuations are usually the main cause of hesperidin-related defects formed during evaporator operation and found in the final juice concentrate. A good procedure is to minimise the time fruit stays in storage bins, preferably less than 24 hours. Storage for longer times, however, does occur.
After harvesting, fruit picked in the groves is loaded onto trucks (typically 20 tonnes in Florida) and taken to the processing plant. Figure 5.3 shows the subsequent processing flow at the fruit reception. Truck unloading
The trucks are unloaded onto a specially designed tipping ramp. The ramp lifts the front of the truck to allow the fruit to roll off the rear of the trailer directly onto a conveyor. The fruit is then conveyed to the prewash station. Alternatively, the truck may be reversed down a ramp so that the fruit is unloaded directly onto a conveyor. Prewashing, destemming and pregrading
The fruit may undergo initial washing to remove dust, dirt and pesticide residues. Some processors have discontinued washing the fruit before bin storage because wet fruit in the bins can make downstream sanitation more difficult. The fruit then moves on to destemming and pregrading. The roller conveyor of the destemming and pregrading tables allows any leaves or twigs to fall through the conveyor bed. Pregrading by manual inspection removes rotten and visibly damaged fruit. Rejected fruit, known as culls, may be sent to the feed mill. Water used for prewashing is often condensate recovered from the evaporation process. There is a strong desire to reduce total water consumption in orange processing plants.
Surge bin
Fruit is drawn from the storage bins into the surge bin where fruit from one or more storage bins may be combined. Final fruit washing
Thorough washing of the fruit is carried out immediately before the extraction process. The wash water may include a mild disinfectant to help reduce the microbial population on the fruit surface. Fresh water or condensate recovered from the evaporators is used for final washing.
Sampling
A sample of fruit is taken for analysis from each truck. The main parameters analysed are juice yield, °Brix, acidity and colour. This gives the processor an indication of fruit ripeness. As the fruit goes into bin storage, each load can be tagged and identified. It is then possible to select suitable fruit from various sources for blending during the extraction process to achieve the desired final product quality. The measured juice yield may also form the basis for payment to the fruit supplier.
Final grading
The fruit passes over a series of grading tables for final visual inspection where damaged or unsuitable fruit is removed.
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5.4 Juice extraction
Peel oil extraction
Extractor, reamer-type
Alt.1
Fruit sizer
Pulpy juice Oil emulsion
Wet peel, rag, seeds
Clarification
Pulpy juice
Alt.2
Extractor, squeezer-type
Fig. 5.4 The juice extraction process.
Oil emulsion
Peel oil recovery
Wet peel, rag, seeds
Feed mill
5.4 Juice extraction
Fruit sizing
The aim of the juice extraction process (see Figure 5.4) is to obtain as much juice out of the fruit as possible while preventing rag, oil and other components of the fruit from entering the juice. These may lead to bitterness in taste or other defects later during juice storage. The extraction operation determines product quality and yield, and therefore has a major effect on the total economics of the fruit processing operation. Once the fruit has been washed and graded (inspected), it is ready for the extraction process. To optimise extractor performance, the raw fruit must be sorted according to size because individual extractors are set to handle fruit of only a certain size range.
After grading, the fruit passes over the sizing table which divides the fruit into different streams according to fruit diameter. A sizing table is generally made up of a series of rotating rollers over which the fruit passes. The distance between the rollers is preset, and increases as the fruit travels over the table. Over the first set of rollers, the smallest fruit drop between the gap onto a conveyor which carries them to an extractor set for their particular size range. As the gap increases, larger fruit will pass through the rollers onto extractors set for their defined size range. In this way, all the fruit is selected to suit the individual settings of the extractors. There are normally 2–3 different size settings in an extractor line. A well-functioning fruit sizer is essential to producing juice of high quality and/or yield. If the fruit is too big or small, then (depending on the extractor type) it will be oversqueezed and excessive rag and peel will get into the juice with resulting bitterness. If the fruit is undersqueezed, insufficient yield will result.
THREE STREAMS RESULT FROM THE EX TRACTION SECTION
5.4.1 EXTRACTOR TYPES Oil emulsion, containing oil from the peel and water, goes to peel oil recovery.
Two types of extractor dominate in orange processing plants, the squeezer type and the reamer type. For these two types there are two major brands, FMC (squeezer type) and Brown (reamer type). Both extraction systems are dedicated to citrus fruit. The reamer-type extraction system provides excellent separation of the orange components juice, oil and peel.
Wet peel together with pulp, rag and seeds, flows directly to the feed mill. Pulpy juice, goes to clarification and then production of concentrate or NFC. Pulp intended for sale as pulp goes to pulp production. Residual pulp goes to pulp washing or the feed mill.
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5.4 Juice extraction
It works best – as regards both product quality and yield – with fruit round in shape and of uniform ripeness such as found with Florida fruit. Squeezer-type extracFig. 5.5 A squeezer-type orange juice extractor. tors are less sensitive to the size and shape of the fruit but can lead to higher oil content in the juice and more damaged pulp compared with reamer-type extractors. Adjustments to the standard squeezer-type extractor may be needed to keep oil levels low and/or improve pulp quality. Globally, squeezer-type extractors are the most common. However, in Florida, the total installed extraction capacity is about equal for both types of extractor. The major share of the NFC produced in Florida is extracted using reamer-type extractors. Another type of extraction equipment is the rotary press extractor. These are more multipurpose machines and therefore may also be used to process other types of fruit. With rotary press extractors, the fruit is cut in half and the halves pass between rotating cylinders which press out the juice. Oil is extracted from the peel in a separate step prior to extraction. Although the extraction process is simple, both juice yield and quality are less optimal compared with squeezer-type and reamer-type extractors. Rotary press extractors, which have a high capacity per unit and require lower investment, are popular in the Mediterranean area. However, globally they are of minor importance compared with squeezer- and reamer-type extractors. Once installed in a plant, extraction systems are not easily interchangeable due to the different demands on the surrounding equipment.
5.4.2 THE SQUEEZER-TYPE EXTRACTOR
A squeezer-type extractor is shown in Figure 5.5. These are placed in lines in the extractor room with up to 15 extractors per line. Each extractor may be fitted with 5 heads, which are available in different sizes so that they can handle the type and quality of fruit available. Typical sizes are 23⁄8, 3, 4 and even 5 inches (used mainly for grapefruit). The head size for each extractor in a line is chosen to optimise the handling of sized fruit. The extractor separates the fruit into four parts – pulpy juice, peel, core (rag, seeds and pulp) and oil emulsion. Fig. 5.6 Operation of the squeezer-type orange juice extractor. Water Whole fruit
Peel
Juice manifold Oil emulsion
Pulpy juice Core
The head of an extractor comprises an upper and a lower cup (see Figure 5.6). The cups have metal fingers that mesh together as the upper cup is lowered onto the lower cup. A cutter comes up through the centre of the lower cup to cut a hole through the skin in order to allow the inner parts of the orange to flow out. The cutter is part of the perforated strainer tube, sometimes referred to as the prefinisher. Once the strainer tube has cut into the fruit, the upper cup squeezes down on the lower cup. This pressure initially forces the juice to burst out of the juice vesicles and pass through the perforations of the strainer tube. Some of the pieces of the ruptured juice sacs (i.e. pulp) will pass through with the juice. The upper cup continues to squeeze down on the lower cup to extract as much juice as possible.
are two major types “There of extractor system, squeezer type and reamer type
” 69
5.4 Juice extraction
Eventually, the downward pressure causes the peel to break up, disintegrate and pass up through the fingers of each cup. Juice flows through the strainer tube into the juice manifold. The core material is discharged from the bottom of the strainer tube through the orifice tube. As the peel is forced through the fingers of the cups during the last step of the extraction cycle, oil is released from the peel. The bits of peel are washed with recycled water to extract the oil from the oil sacs. The oil is discharged from the extractors as an emulsion with water. With squeezer-type extractors, one item of equipment – the extractor – separates the fruit into four principal product streams in one basic step. It is claimed that contact is avoided between the juice and oil, and the juice and peel. For successful operation of this equipment, the correct selection of cup size and adjustment of cup and cutter operation are important. Too much pressure applied to fruit resulting from the use of undersize cups may result in blowing out the fruit and/or peel entering the juice stream. If too little pressure is applied the yield will drop. The throughput of a five-head extractor will vary according to the quality and size of fruit. The standard operating speed is 100 rpm, or 500 oranges per minute. Fruit will not always flow to each cup; 90 % utilisation is a high figure. A typical capacity for medium-sized fruit is 5 tonnes/hr of fruit per extractor, corresponding to about 2500 l/h of juice. Because extractors operate at a fixed number of oranges processed per minute, the citrus processing plant throughput is very sensitive and dependent on fruit size. Processing small fruit (350 oranges/box) will result in 1500 l/h juice flow rate instead of 3000 l/h when processing large fruit (180 oranges/box), an increase of 100 % related to the quantity of juice and by-products handled by downstream equipment. These figures show the importance of correct storage bin management and fruit size in smooth factory operations.
Modifications for premium pulp
As the pulpy juice passes through the holes in the strainer tube in the standard extractor, the pulp tends to be broken up into small pieces, typically 2–3 mm in length or less. This is acceptable if the pulp is intended for pulp wash and as commercial pulp for certain markets. Market demands in the juice market are changing, and the need for more “natural” pulp that has been subjected to less shear is increasing. In a squeezer-type extractor of modified design, larger pulp pieces, up to 15–20 mm long, flow along with the juice stream. The main difference in design is the use of a modified strainer tube with larger openings that allow more pulp to remain in the juice stream. The pulp is subsequently separated from the juice and treated in a modified pulp recovery system. Modifications to the squeezer-type extractor to suit premium pulp were introduced in the 1990's and today there are several installations in Florida and Brazil. Premium juice “low-oil” extractor
Certain fruit varieties (e.g. the Florida Valencia) will express more oil into the juice stream than other varieties. This can lead to oil content in the juice exceeding acceptable levels (such as 0.035 %, the maximum level permitted in Florida for grade “A” juice). This is a problem with NFC but less so with juice intended for concentrate because most of the oil will flash off in the evaporator. In the lowoil version of the squeezer-type extractor, the design of the strainer tube and orifice tube area are modified. This unit cuts a smaller core and puts less pressure on the fruit during extraction, thereby reducing the amount of peel oil getting into the juice. These modifications may also lead to a reduction in juice yield. When the top spray of water is stopped, the amount of peel oil to be recovered is thereby reduced. As an alternative, hermetic centrifuges or vacuum flashing can be used for deoiling the singlestrength juice in conjunction with the standard extractors. This allows a higher juice yield to be maintained during extraction, while excess oil is removed after the extraction process.
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5.4 Juice extraction
5.4.3 THE REAMER-TYPE EXTRACTOR
The reamer-type extractor is based on the same principle as a typical manual kitchen squeezer used to prepare orange juice for breakfast. An extraction line comprises several extractors, and it is very important to set up each extractor to suit the size of fruit fed into it. A reamer-type extractor is illustrated in Figure 5.7. Fruit is fed into the feed wheel and cut in half. The halves are oriented and picked up in synthetic rubber cups mounted on a continuous belt system. A series of nylon reamers (cone-shaped inserts that have ridges moulded into the form from tip to base of the reamer) are mounted on a rotating turntable. The reamers, in the vertical plane for most models, enter each fruit half and rotate as they penetrate them. The speed of rotation varies as the reamer penetrates the fruit, being slower towards the end of the operation. Juice, pulp, rag and seeds pass out through one outlet, and the remaining peel passes out through the peel chute. The juice and pulp are separated from the rag and seeds by a strainer, then pass on to the finishers. The size, pressure and rotation speed of the reamer can be adjusted to suit the maturity, size and quality of fruit. The reamer-type system typically gives a better quality of pulp (longer and larger cell fragments) than standard squeezer-type extractors. Juice yields between the two systems are comparable.
Fruit
Juice
Fig. 5.7 A reamer-type orange juice extractor. The oil extraction system
Peel oil can be recovered from the peel using a separate oil extraction system which is placed upstream of the juice extractors. It operates on the principle of puncturing oil sacs in the flavedo and washing the oil out to make an emulsion (see Figure 5.8). In the first stage of the oil extraction system, whole fruit passes over a series of rollers with small but sharp needle-like projections. The oil glands are pricked rather than scraped open so that little damage is done to the peel. Therefore, the amount of contaminating material washed away with the oil is minimal. This, in turn, makes the water stream separated from the emulsion cleaner and easier to recycle.
Water Fruit
Water Oil emulsion
Oil emulsion
Fig 5.8 An oil extraction system.
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5.5 Clarification
The rollers conveying fruit are Pulpy juice placed in a water bath and the oil from extractors from the pierced glands is washed out with water. After a finishing (straining) stage to remove any large particles of peel, the oil-water Pulp emulsion can be concentrated and Finisher 1 Finisher 2 Pulp wash polished in a series of centrifuges production/ (see subsection 5.8 on peel oil refeed mill Juice Juice covery). The water is recycled to a large degree. Instead of more recently developed oil extraction system Clarifying centrifuge upstream of juice extraction, older installations incorporate peel shavers placed after the juice extraction stage. The outer layer of flavedo is Product chiller literally shaved off from the peel mechanically. It is washed and pressed to remove the oil. The Buffer storage tank emulsion is then centrifuged in the conventional manner. The reamer-type extraction system requires two separate steps to extract juice and oil from the fruit. Concentrate production NFC production Nevertheless, the oil emulsion is often considered cleaner, easier to Fig. 5.9 The clarification process. centrifuge compared with other types oil recovery system, and the extracted juice has less contact with the oil. 5.4.4 DOWNSTREAM OF THE JUICE EXTRACTORS
5.5 Clarification The juice leaving the extraction process is clarified as it contains too much pulp and membrane material to be processed in the evaporator or as NFC. Typical process steps in juice clarification are shown in Figure 5.9. Pulp levels in pulpy juice from the extractors are generally around 20–25 % of floating and sinking pulp. The juice is therefore finished, that is, pulp is removed from the juice. A finisher is basically a cylindrical sieving screen. There are two types of finisher – screw-type and paddle. Their operating principles are shown in Figures 5.10 and 5.11.
The juice streams leaving either a squeezer-type extractor line or reamer-type extractor system flow to clarification and then evaporation, or pasteurisation if the end-product is NFC. The oil emulsion flows to peel oil recovery for separation by centrifugation. Peel, rag, seeds and other solid material are conveyed to the feed mill.
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5.5 Clarification
The standard squeezer-type extractor includes a prefinishing tube in the extractor and the pulpy juice flows directly to the primary finisher.
Screw-type finishers
These include a stainless-steel screw that conveys the pulpy juice through the unit and presses the pulp against the cylindrical screen. The juice flows through the screen holes. The pulp is consequently “concentrated” inside the screen and is discharged at the end of the finisher. As pulp is discharged through a restricted opening, the resulting back-pressure in the finisher helps to squeeze out more juice from the pulp mass.
Centrifugal clarification
Typically, the pulp content in juice leaving the secondary finisher is about 12 %. This pulp is predominately sinking pulp. If the market requires a juice with lower sinking pulp content, the juice can be further clarified by centrifugation. A two-phase clarifier is normally used for this application. Separation in the disc stack centrifuge takes place in the spaces created between a number of conical discs stacked on top of each other to provide a large separation area. Most models rotate at between 4,000 and 10,000 rpm. The accumulated solids can be discharged, without having to stop the centrifuge, by rapidly opening an annular slot at the periphery of the rotating bowl. The clarified juice leaves the centrifuge under pressure. Clarification by centrifugation often leads to improved operation of the evaporator system by providing consistent pulp levels in the juice. In order to meet recent demands for FCOJ with very low and low pulp content (<1 and <3 % pulp respectively) for use in the production of orange nectars and drinks, a new type of hermetic centrifuge with continuous pulp discharge is applied. Usually this type of machine is located within the evaporator system, between stages, in order to centrifuge warm juice. This type of hermetic centrifuge can reduce pulp levels to less than 1 % without frequent intermittent discharges.
Paddle finishers
These incorporate a set of paddles rotating on a central shaft within the cylinder. The pulp is pushed against the screen by the paddles. Paddle finishers apply centrifugal force rather than pressure to separate the pulp from the juice. This usually provides gentler pulp treatment and higher flow rates than screw finishers. Two finishers are often placed in series at the end of the extraction line. The upstream primary finisher is not set as tight as the downstream secondary unit and so will have a higher flow capacity. The exact configuration of the clarification stage depends upon the manufacturer of the extractor system and the type of pulp that the processor wishes to recover. The pulpy juice stream from a reamer-type system or premium pulp squeezer-type extractor may first pass through a classifying finisher (with larger holes) to remove peel and membrane pieces before pulp recovery.
Pulpy juice
Pulpy juice
Pulp
Pulp
Finished juice
Finished juice
Fig. 5.10 Operation of screw-type finishers.
Fig. 5.11 Operation of paddle finishers.
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5.6 NFC production
Juice from clarification
Buffer tank
Deoiling centrifuge Pasteuriser
Frozen drum storage
Chilled aseptic tank storage
Deaerator
Chilled aseptic bag-in-box storage
Fig. 5.12 NFC production through to bulk storage.
Turbofilters
5.6 NFC production
Turbofilters were introduced in Brazil during the mid-1990’s as an alternative to screw and paddle finishers. Turbofilters are claimed to give a more stable level of sinking pulp in the finished juice than conventional finishers. They incorporate a stainless-steel conveyor, rotating faster than screw finishers, which pushes the pulpy juice against a plastic screen. The pulp content of the juice can be adjusted by changing the inclination of the turbofilter.
The aim of NFC processing is to produce orange juice using the minimum of thermal processing. Nevertheless, the thermal treatment should be sufficient to ensure that the product is physically and microbiologically stable. Since fruit harvesting is seasonal and juice consumption is year-round, the product must be stable enough to be stored for several months up to one year so that seasons can be bridged. In some instances during the season, NFC is pasteurised and packaged for the retail market without long-term bulk storage. When this is the case, some blending may occur following the clarification step to minimise hourly variations in acidity and °Brix. Some pulp may also be added depending upon market demands. More commonly, the juice is processed and stored in bulk under aseptic or frozen conditions for some months until it is reprocessed and packaged. For large-volume NFC production, such as found in Florida and Brazil, aseptic tank farms are the most common form of NFC storage.
Blending
After clarification, the juice often undergoes some degree of blending with juice from other batches in order to balance its flavour, colour, acidity and °Brix levels before further processing. If intended for NFC production, the juice leaving the clarification section should be cooled to 4 °C to minimise the potential of microbiological activity before being passed into the buffer/blending tanks.
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5.6 NFC production
Juice oil
Reduction of oil can be achieved in different ways: Adjusting the extractor. Less pressure is applied to fruit during extraction or a low-oil extractor (squeezer-type) is used. Both alternatives are likely to reduce juice yield.
Deoiled juice
Vacuum flashing of preheated juice. This method can remove desirable volatiles from the juice along with the oil. Centrifugal separation of the oil phase from the clarified juice. With this method juice yield from the extractors can be maintained at a high level and there is no heating of the juice. Fig. 5.13 Operational principle of a hermetic centrifuge for deoiling juice.
Deoiling with centrifuges
Removal of oil from single-strength juice with centrifuges has been practised for years. It is a difficult separation task because the oil droplets are well emulsified, particularly in juice from squeezer-type extractors. Hermetic centrifuges give good results in separating oil even from juice coming from squeezer-type extractors. In a hermetic centrifuge the rotating bowl is completely filled with liquid. This means that there are no air pockets and thus no free liquid surfaces in the bowl, which in turn avoids air entrainment and high shear forces. The feed enters the centrifuge bowl from underneath through a hollow spindle. (See Figure 5.13).The smooth acceleration of the product as it enters the centrifuge prevents scattering of the oil globules, thereby enhancing separation. The hermetic (gastight) design also prevents loss of volatile components in the juice and ingress of oxygen. In the deoiling of single-strength juice with hermetic centrifuges, oil concentrations can typically be reduced from 0.04–0.08 % to 0.02–0.035 %. In terms of juice yield, the use of a deoiling centrifuge in combination with standard extractors gives a yield increase of 2–4 % compared with an extractor fitted with low-oil components. The deoiled juice is buffer-stored for a short period prior to pasteurisation. Some blending to level quality variations may be carried out.
The reprocessing often involves the blending of juice from early and late season fruit in order to standardise °Brix, ratio, colour, etc. The addition of pulp to the consumer product may be done at this stage. Sometimes, if volatiles have been removed from the juice prior to storage, these are added back to the juice during the blending step. The steps for NFC production up to bulk storage are shown in Figure 5.12. After clarification, but prior to buffer storage, the product should be cooled as soon as possible to prevent microbiological growth or enzymatic reactions. A plate or tubular heat exchanger can be used for cooling, the choice of which will be dictated by the type and quantity of pulp present in the juice. However, cooling is seldom done before pasteurisation in a traditional citrus processing facility. 5.6.1 OIL REDUCTION
Depending upon fruit variety and extractor operation, the oil content in the juice from extraction may exceed acceptable amounts. The levels may be specified by a legal standard, for example Florida grade A juice should have a maximum oil content of 0.035 %. Alternatively, the oil content may be decided on the basis of consumer preference. Acceptable levels of oil in juice ready for consumption range from 0.015 to 0.030 %.
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5.6 NFC production
dissolved oxygen. It also contains some free air. During product storage, oxygen present in juice in the dissolved state and as free bubbles may destroy a significant amount of the available vitamin C by oxidation (see also Section 4). Air bubbles present in the product during pasteurisation may also lead to insufficient heat treatment. Deaeration as part of the pasteurisation process is therefore recommended for the production of NFC. Deaeration is usually carried out by passing the product through a vacuum chamber. Free air bubbles expand in a vacuum and tend to escape quite easily from the juice, although dissolved oxygen is more difficult to remove. The deaeration efficiency, or reduction of dissolved oxygen, depends on several operating factors, such as the vacuum applied and juice surface area in the deaerator. Deaerator operation and equipment are described in subsection 7.5. Volatiles which flash off during deaeration are condensed and returned to the juice stream. Alternatively, they are sometimes removed and stored separately from the bulk juice.
5.6.2 PRIMARY PASTEURISATION
Pasteurisation prior to storage, the primary pasteurisation, must achieve two goals – to deactivate the enzymes present in the juice and to make the juice microbiologically stable. (See also subsection 4.4). It is carried out using tubular or plate heat exchangers. The choice of heat exchanger depends on the amount and type of pulp in the product and on the processor’s preference. Tubular heat exchangers are best for juice containing floating pulp (see also subsection 7.5). Normally, after bulk storage the juice is pasteurised at least a second time prior to filling into retail packages. The long shelf life required for NFC going to bulk storage demands strict attention to hygiene. Single-strength juice is more sensitive to microbial contamination than concentrate (where the high osmotic pressure resulting from high sugar content retards microbial growth). The use of chilled storage instead of frozen storage also imposes much stricter hygiene requirements for NFC production than what FCOJ producers may be accustomed to. Good manufacturing practice demands that the pasteuriser system should be presterilised at 95 °C or higher prior to production, and that a CIP program be integrated with the control system. NFC volumes to be processed are normally large, so a high degree of energy recovery is advisable. Thermal treatment is a concern among many NFC producers. Excessive heat load on the juice should be avoided. Careful control of temperature and residence time using well-designed heat exchangers is important. Low temperature differentials between the heating medium (hot water) and product minimises “shock” to the product.
oxygen in juice causes “Dissolved loss of vitamin C during storage ” 5.6.4 LONG-TERM FROZEN STORAGE
After primary pasteurisation orange juice is stored in bulk under either frozen or aseptic conditions. NFC production involves large product volumes. For the same amount of final juice, NFC volumes are 5–6 times larger than FCOJ. Vitamin degradation and changes in flavour during the storage period are minimised by freezing, but the energy and warehouse costs of freezing and storing frozen NFC are high. Freezing of NFC leads to handling problems because it freezes solid, whereas frozen orange concentrate is very viscous but still pumpable. Frozen storage of NFC is more appropriate to low NFC volumes. Large-volume producers store NFC aseptically in very large tanks. Juice to be stored frozen is filled into mild steel 200 l (55 US gal.) drums lined with a polyethylene plastic bag. As the product is to be frozen, the net filling volume is about 170 l (45 US gal.).
THE PURPOSE OF PRIMARY PASTEURISATION IS TWO-FOLD - to deactivate enzymes - to make the juice microbiologically stable
5.6.3 DEAERATION
Air tends to get mixed into the juice in the extractors and finishers. Some of the entrained air may escape during buffer storage, but juice going to pasteurisation is normally saturated with
76
5.6 NFC production
Normally, when product is required from these tanks, it is drawn off, blended with juice from another part of the season (and perhaps pulp) and repasteurised. In Florida, a large share of NFC is stored in tank farms with very large aseptic tanks. This technology was pioneered in Florida and gave rise to rapid growth in storage capacity during the 1990’s with still more capacity being added today. Growth in NFC production in Brazil after 2000 has also led to the construction of large storage tanks. But unlike Florida, where NFC is mainly stored and utilised on a processor’s site, NFC produced in Brazil is primarily intended for export. The aseptic tank farms are therefore installed at the dockside export terminal instead of at the juice factory. In this case, clarified juice is pre-pasteurised and cooled down to 0 °C at the processing site and then transported by road tanker to juice facilities at the export harbour (the distance from one of the major citrus processing sites to Port of Santos is 450 km). Full pasteurisation of juice takes place at the terminal before it is transferred to the large aseptic storage tanks for long-term storage to bridge the seasons. To avoid repasteurisation of juice before overseas transport, relevant technology has been developed that allows the aseptic transfer of juice to sea vessels fitted with bulk aseptic tanks. Juice is transported to the US and Europe under chilled aseptic conditions on board specially designed ships (see also subsection 6.3.3). On arrival at its destination, the juice is aseptically transferred to aseptic dockside tanks at the reception terminal using similar technology to that at the export facilities. The aseptic NFC technology requires a substantial initial investment, and the value of product at risk when stored in such large tanks is considerable. Today, however, risks are minimised by field-proven designs, advanced aseptic technology, and more than ten years of experience with the many large tank systems installed.
THERE ARE THREE MAJOR OPTIONS FOR LONG-TERM STORAGE OF NFC JUICE - frozen storage - aseptic storage in tanks - aseptic storage in bag-in-box bulk containers
Alternatively, the juice may be poured into block formers and then frozen (mainly for on-site storage).The frozen product is usually kept at –18 °C or lower. Thawing of NFC to make it ready for final processing also leads to some logistical and handling difficulties. It takes several days or weeks for bulk product in drums to thaw at ambient temperature. The outer layer of juice may be exposed to microbiological contamination during thawing with subsequent negative impact on product quality. Crushing systems enable more rapid handling but entail higher energy consumption and capital investment. Systems for freezing larger blocks of juice incorporating novel techniques for rapid freezing and thawing have been introduced, but so far have limited commercial use. 5.6.5 ASEPTIC STORAGE IN TANKS
As an alternative to frozen storage, NFC may be stored chilled in aseptic tanks. Technology exists to build very large tanks, up to 4 million litres capacity, for the aseptic storage of juice. Unique fabrication techniques are used to coat the internal surfaces of the carbon steel tanks with an expoxy lining. While lined tanks are common in Florida, Brazilian producers use mainly stainless-steel tanks for NFC storage. The tanks are sterilised prior to filling by flooding them with a sterilising fluid (e.g. iodoform). Rather than fitting the tanks with cooling jackets, they are installed within a large refrigerated building. The preferred storage temperature is about –1 °C, just above the freezing temperature of the juice. The juice must be agitated periodically to avoid separation of sinking pulp and to maintain °Brix uniformity. Pressurised nitrogen above the juice surface is often maintained to minimise the risk of vitamin C loss through oxidation.
an alternative to frozen “As storage, NFC may be stored chilled in large aseptic tanks
”
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5.6 NFC production
5.6.6 ASEPTIC STORAGE IN BAG-IN-BOX BULK CONTAINERS
As an alternative to aseptic tanks, the juice may be filled into 1,000 l (300 gal.) aseptic bag-in-box containers (see Figure 5.14). The bags, placed in bins usually made from wood, are then stored under refrigerated conditions. After storage, the product is accessed by opening the bag and pumping out the product. Alternatively, the bag can be emptied and the juice transferred aseptically to the filler. The use of “one tonne” aseptic bag-in-box containers for NFC storage requires more labour for filling and emptying the containers compared with large tanks. However, it gives added flexibility regarding storage capacity as the investment required to store additional volumes of juice is moderate. A drawback of the aseptic tank approach is finite storage volume unless a major investment is undertaken to have reserve capacity. Consequently, the bag-in-box solution is often preferred for start-up operations for NFC production. NFC processors who already have aseptic tanks installed may also use bag-in-box containers to provide additional storage capacity and shipment of NFC. Aseptic security during product filling and storage in the bag must be high. For long-term storage of juice (6 months or more), bag material with a very good oxygen barrier is recommended. Bags made with foil-based aluminium laminate offer higher protection against oxygen compared with metallised laminates where the aluminium layer is much thinner. Aseptic security during product filling and storage must be high. Any contamination may lead to blown bags during storage and shipment. Needless to say, a single blown bag during shipment can cause a lot of trouble. There are several filling systems for aseptic bag-in-box (BiB) containers. Some evolved from conventional (nonaseptic) BiB systems. A sterile chamber surrounds the filling head, and chemical sterilants are used for sterilisation.
Fig. 5.14 A filler for bag-in-box containers.
Other systems were developed specifically for aseptic filling. An example of the latter type is shown in Figure 5.14. It incorporates a simple filling system (spout and filling valve) and steam is used as the sterilising agent. 5.6.7 REPROCESSING OF NFC
In the USA, some NFC is moved in bulk by road and rail tankers to juice packers across the country, but most NFC is filled into retail packages in Florida and distributed from there. Shipping from Florida to Europe in bulk is done in frozen drums and aseptic bag-in-box containers. For Brazilian NFC, overseas shipping also occurs by bulk sea tanker. Overseas shipping of packaged product is at a cost disadvantage compared with shipping bulk juice. Moreover, the additional delay in transport time adds to difficulties with logistics and forecasting for the packaged product. Traditionally, NFC taken from storage at the fruit processor’s site for reprocessing is blended with juice from a different part of the season and/ or with pulp. The juice blend is then repasteurised prior to filling into consumer packages. Alternatively, specially designed equipment can be used to transfer juice from aseptic bulk bags to consumer packages, via an aseptic tank, without the need for repasteurisation. When NFC is shipped overseas, blending with other orange juice varieties and pulp may take place at the juice facilities at the reception terminal or at a blending house.
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5.7 Concentrate production
Juice from clarification
Evaporator
Condensate to fruit washing
Essence recovery Concentrate blend tanks
Plate cooler
Frozen concentrate storage
5.7 Concentrate production
Fig. 5.15 Flow chart of concentrate production.
During the 1970´s and 1980´s, there was a large expansion in concentrate capacity in the major citrus markets of Brazil and Florida. Today, little increase in evaporator capacity is needed in these regions, but new evaporators are being installed to satisfy the requirements of other expanding orange-producing regions.
Globally, most orange juice is produced as concentrate. Juice from the clarification step is evaporated to remove most of the water (see Figure 5.15). Currently, the most widely used citrus evaporators are of tubular design, although plate and cassette evaporators are also installed in citrus plants. The evaporators are designed for the enormous juice volumes commonly processed in large citrus plants, where evaporator capacities can exceed 100,000 kg/h (about 220,000 lbs/h) of water evaporated. Versions with as many as seven effects are installed (seven effects means basically that the steam is reused to evaporate water in seven steps). Such systems have a very low specific steam consumption; only 1 kg (2.2 lbs) of steam is used to evaporate 6 kg (13.2 lbs) of water. However, additional effects increase the residence time for the product in the evaporator accordingly.
5.7.1 TUBULAR EVAPORATOR SYSTEMS
The most common type of tubular evaporator system used for orange juice is the TASTE evaporator. It is generally described as a continuous, high-temperature short-time evaporator of the long, vertical tube falling-film type. The name is an acronym for Thermally Accelerated Short-Time Evaporator. It was designed and developed in Florida, and today this type of evaporator is manufactured in many different countries. These evaporator systems are dedicated to citrus fruit.
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5.7 Concentrate production
Preheated juice
3
5
1 Steam 7
4
6
2
Steam
Steam 1
Condensate Concentrate 65 °Brix
= Product stage
Juice 12 °Brix
Fig. 5.16 A simplified flow diagram of a tubular evaporator.
A flow diagram of an evaporator with seven product stages is presented in Figure 5.16. The juice is first preheated to 95–98 °C. Holding at pasteurisation temperature stabilises the juice by means of microbial and enzyme inactivation. The product then passes through a number of stages under vacuum until a concentration of up to 66 °Brix is achieved. By this time the product temperature has fallen to about 40 °C. The residence time in the evaporator is typically 5–7 minutes or longer. Good distribution is of primary importance in the design of an evaporator. It ensures that all the product is uniformly treated and that the heat exchange surface is used to its maximum potential. A special feature of the TASTE evaporator is the way in which the product is distributed across the tube bundle. The juice is fed into the distribution section at a temperature and pressure greater than in the entry zone of the tube bundle. The liquid is fed through a diverging expansion nozzle which converts all the product into a liquid/vapour mixture. The expanding vapour accelerates the liquid/vapour mixture through a second nozzle and cone assembly. Further flash expansion of the vapour causes atomisation of the liquid phase into a turbulent mist. The acceleration effect can cause mist velocities to exceed
50 metres/second on leaving the tube bundle! The high degree of turbulence increases heat-transfer rates and reduces burn-on, which helps to achieve long operating runs. Other tubular evaporation systems
There are also other tubular evaporator systems of similar design for citrus plants, which include a conventional mechanical method of distributing product across the tube bundles. They in cor po rate thermal recompression to increase steam economy without increasing residence time. Relatively few of these evapo ra tor sys tems have been installed for high product capacities. 5.7.2 PLATE AND CASSETTE EVAPORATOR SYSTEMS
In addition to tubular systems, plate and cassette evaporators are also used for concentrating orange juice. As the name implies, plate evaporators consist of plates clamped together in a frame with gaskets between them. It is more common to use cassettes (welded double plates) instead of single plates because they further simplify maintenance. The heating medium (steam or vapour) flows through the space between the welded plates that make up the cassette.
80
5.7 Concentrate production
Fig. 5.17 A rising film cassette evaporator.
Product channels are formed between individual cassettes separated by gaskets. This configuration allows ready inspection of product. Some advantages of plate/cassette evaporators when compared with other types of evaporator are that capacity increases are easily achieved by adding more cassettes, and that maintenance and inspection are easily carried out by opening the frame. Furthermore, as cassette evaporators are more compact, they eliminate the need for several walkways at different levels used to access the equipment as found with tubular systems. The onelevel configuration offers easy operator control and ready access for maintenance activities. A small temperature difference between the product and heating medium is sufficient in this type of evaporator. This allows lower operating temperatures to be used than with traditional tubular evaporators. The main type of cassette evaporator is the rising film unit.
The film flows upwards in a homogenous flow thus giving a very short retention time over the heating surface. The liquid/vapour velocity at the outlet of the very short heating channel is very high. It is possible to evaporate products of higher viscosity and higher pulp content than in a falling film evaporator. As plate systems can be designed for flexibility, some installations installed in citrus plants are used to process other types of juice outside the orange juice season. 5.7.3 HOMOGENISATION
Sometimes, homogenisation of concentrate is carried out within the evaporator system. Product then normally passes through a homogeniser before the last effect. At this stage the concentration is approximately 40–42 °Brix. Homogenisation breaks down the pectin, thereby lowering the viscosity of the concentrate. This increases the efficiency of the final stage of the evaporator. It is also claimed that homogenisation reduces the sinking pulp level in the product. This could permit juice with higher pulp levels to be fed to the evaporator. In the case of special requirements of concentrate with very low pulp content (<1 %), specially designed hermetic clarifying centrifuges may be included in the evaporator system.
Rising film cassette evaporator
In the rising film cassette evaporator the product enters the bottom of the cassette and rises up over the heating surface as it boils (Figure 5.17). No mechanical feed distribution device is needed and even distribution is achieved through gravity.
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5.7 Concentrate production
Concentrate
Juice feed
5.7.4 THE CENTRIFUGAL EVAPORATOR
Very gentle product treatment during evaporation is achieved in the centrifugal thin-film evaporator (Figure 5.18). The heating surface consists of rotating cones. By combining heating and centrifugal force, a high degree of concentration takes place in one single pass, in a very short time and at a very low temperature. A typical residence time for concentrating orange juice from 12 to 65 °Brix is about 10 sec at a temperature of 50 °C. These gentle conditions give the lowest possible thermal impact on the product. The centrifugal evaporator (Centritherm) handles capacities from 50 to 5,000 kg/h of evaporated water. It is configured in one effect and consequently has a specific steam consumption of approx. 1.1 kg steam per kg water evaporated. Although its capacity is too low and steam consumption is too high for cost-effective production of standard concentrates, the superior heat-transfer efficiency and gentle product treatment of the centrifugal thin-film evaporator are desirable features of units sometimes used for producing premium concentrates that command a high market price.
Vapour
Condensate
Fig. 5.18 The operational principle of a centrifugal evaporator.
Some recently designed essence recovery systems use structured packing in the distillation column instead of the traditional perforated plate device. This new approach results in less aroma liquid hold-up volume and residence time as well as increased separation efficiency. These features help to improve the yield of both water phase aroma components and essence oil.
5.7.5 ESSENCE RECOVERY
During evaporation volatile juice components are stripped from the juice together with the water. These are often recovered in an essence recovery system connected to the evaporator. The essence process usually forms an integral part of the mass and thermal balance of the evaporator system. Dr. James Redd of Florida pioneered the development work in the design of essence recovery units, the first commercial system being installed in 1963. The vapours from the early product stages of the evaporator contain most of the volatiles from the juice. These are captured and sent to a still mounted on the evaporator. The important volatiles are separated from the water by distillation under vacuum and condensed by chilling. The product essence is a concentrated mixture of aqueous and oil-soluble aroma compounds. This essence is separated into oil and aqueous phases by either decantation or centrifugation.
Water phase aroma and essence oil
The aqueous phase (called water phase aroma or essence aroma), contains the flavour top-notes. It has an alcohol strength typically standardised at 12–15 %. The oil phase (essence oil) holds the fruity and sweet-tasting flavours of fresh juice. It has different properties to those of peel oil (see Section 8). Add-back of water phase aroma and essence oil to concentrate has replaced the previous practice of adding single-strength juice (called cut-back) to improve the flavour of concentrate. In Florida, Valencia oranges are used to produce the best essence, but little essence can be derived from early varieties of fruit, and it is often of poorer quality. Aroma and essence oil are either sold as separate products to concentrate blending houses or juice packers, or alternatively purchased on contract by speciality flavour manufacturing companies.
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5.7 Concentrate production
5.7.6 CONCENTRATE STORAGE
Freeze-concentration
After evaporation, the 65 °Brix concentrate is chilled to –10 °C. It is then routed to storage. Blending of different production lots and addition of peel oil and essences may be done on the way to concentrate storage. Storage takes place in bulk storage tanks or 200 l drums with plastic liner. Drum storage is normally maintained at –20 to –25 °C, bulk storage in large tanks often at –10 °C. Just prior to dispatch from the plant, concentrate drawn from different bulk storage tanks is often blended to meet product specifications. Concentrates are sometimes diluted with pulp, for example, to reduce the Brix level. Shipping of frozen concentrate involves drums, tank cars or bulk tanker ships. Concentrate is traded as FCOJ. The term ‘frozen’ may be misleading as concentrate at 65 °Brix does not freeze solid at –10 °C due to its high sugar content. 65–66 °Brix is the most common concentration for FCOJ but bulk concentrates of lower °Brix are also available. FCOJ of 55–58 °Brix is typically supplied to dairies.
This method is based on the fact that during the freezing of sugar solutions, ice crystals are first formed which can be separated out from solution, thereby increasing the sugar concentration. When freeze-concentration is applied to juice, inactivation of enzymes is necessary. This may be carried out by pasteurising the juice before freezing or pasteurising the resulting concentrate. Several studies have shown that, compared with conventional evaporation, freeze-concentration yields superior flavour quality. However, the low temperatures involved lead to high viscosities of the concentrated products, which limit the degree of concentration that can be achieved and the amount of pulp and insoluble solids that may be present in the juice to be concentrated (Braddock and Sadler, 1989). Concentrates of up to 40 °Brix can be obtained with this method. Membrane filtration
Membrane filtration is another method evaluated for concentrating orange juice without using heat, but the resulting high viscosity of concentrate reduces filtration efficiency and limits the degree of concentration that can be achieved. To minimise viscosity, the pulp is first separated from the juice, e.g. by ultrafiltration (UF), to leave a clear liquid (serum) which is concentrated by reverse osmosis. The pulpy stream, rich in enzymes, is pasteurised before being recombined with the serum concentrate. Mixing back of the insoluble solids stream, essentially at single-strength juice concentration, reduces the Brix value of the concentrate. Concentrations up to 42 °Brix have been reported. Concentration systems using other membrane processes have also been tested. However, the necessity to retain the sugars, acids and aroma compounds in order to maintain a balanced citrus juice flavour puts tough demands on potential membrane systems.
5.7.7 ALTERNATIVE CONCENTRATION METHODS
Alternatives to evaporation for concentrating orange juice have been developed and tested, but so far their commercial application is limited. Lower Brix levels of the concentrate and often high operational costs compared with evaporator systems in common use hinder the commercialisation of the new systems. Two methods which do not use heat for concentration are freeze-concentration and membrane filtration.
83
5.8 Peel oil (cold-pressed oil) recovery
Peel oil emulsion from extractors
5.8 Peel oil (cold-pressed oil) recovery
Oil finisher
The oil-water emulsion, or oil frit, from the extraction process is sent to the peel oil recovery section. Apart from the oil and water, other fruit substances are present in the emulsion. These include particles of peel and pulp, and soluble pectin and sugars. The aim of the peel oil recovery system is to recover pure oil by removing all other substances with as little oil loss as possible. Peel oil is commonly referred to as coldpressed oil.
First stage centrifuge
Reclaimed water returned to extractors
Second stage centrifuge
Winterisation tanks
5.8.1 STRAINING AND CONCENTRATION STEP
The first step involves using a finisher as a straining method to remove large bits of peel and other parts of the orange that must not enter downstream centrifuges (see Figure 5.19). After straining, the oil emulsion containing about 0.5–2.0 % oil enters the first stage centrifuge (also called a desludger or concentrator). The centrifuge concentrates the oil up to 70–90 %. The first centrifuge is a three-phase machine. The light phase is concentrated oil, the heavy phase is water, and the third phase is residual particulate matter. The control of solids discharge from the sludge space is critical to the overall performance of the oil recovery system. If the discharge frequency is set too high then product is lost, but if the sludge space is allowed to fill up then separation efficiency is lost. The water stream is often recycled back to the oil extraction system as spray water, although it is important that some water is removed from the system to allow additional fresh water to enter it. Microbiological problems may occur if the same water is continuously recycled. Moreover, the centrifuged water contains undesirable components such as soluble pectin. As the concentration of these components builds up in the emulsion, the oil separation efficiency decreases, thereby resulting in lower oil yields. Again, this limits the amount of water recycling possible.
Drum storage
Bulk transport
Fig. 5.19 Flow chart of peel oil recovery.
The centrifuged water also contains microscopic particles of oil that are too small to be separated by the centrifuge. As this level of oil builds up with water recycling, the effectiveness of the water to extract oil from the peel decreases. This will also lead to an overall drop in efficiency of oil recovery. The type of oil extraction used and the performance of the centrifuges will determine the amount of water that can be recycled. The cleaner the peel oil emulsion, the higher the oil yield of the peel oil recovery system and the larger the recycling of water. The oil extraction system upstream of the reamer-type juice extractor is claimed to give a “less contaminated” oil emulsion than the one-step squeezer-type extraction system. For oil recovery, the hermetic centrifuge has several advantages over the open bowl type design. The fully flooded bowl in the hermetic machine ensures that oil does not come in contact with air. The precise manner in which the interface between oil and water is controlled leads to higher separation efficiency.
84
5.8 Peel oil (cold-pressed oil) recovery
The winterisation process involves precipitating the wax by causing it to crystallise and then settle. The oil is stored in tanks at 1 °C or lower, which causes the waxes to come out of solution and sediment. The process typically takes 30 days or more, although at lower temperatures this period may be considerably shorter. The winterised oil is then decanted from the tank. Larger processors collect the sludge from different winterising tanks so that once sufficient material has accumulated, the waxes can be removed by centrifugation to recover residual oil. The winterised oil is packed in 200 l (55 US gal.) drums or road tankers. Normally the oil is stored under refrigeration (–10 °C) and is traded as Cold-Pressed Oil, CPO. Sometimes it is called Cold-Pressed Peel Oil, CPPO. It is used as a raw material in the flavour manufacturing industry, and by concentrate blending houses and drinkbase manufacturers.
Fig. 5.20 Hermetic centrifuge for peel oil concentration.
A hermetic centrifuge for concentration of peel oil emulsion is illustrated in Figure 5.20. 5.8.2 POLISHING
The concentrated oil stream then passes to a second stage centrifugation process (polishing). Within this machine the oil is further concentrated to >99 % purity. The flow rates are extremely small (1–2 %) compared with the flow rates in the first stage, or with flow rates used in juice clarification and deoiling of single-strength juice. Since the product has already undergone one centrifugation process, virtually no solid particles remain in the product. For smaller capacities, a solid bowl machine is used and the water and oil are continuously discharged. Periodic takedown removes any material that collects in the bowl periphery. For larger flow rates, a solids-ejecting polisher is used in which water and oil leave the machine under pressure. Accumulated solids are discharged about once or twice per hour. One tonne of fruit typically yields 200–300 l emulsion to the first centrifuge and 3–6 l of concentrated oil to the polisher.
5.8.4 D-LIMONENE RECOVERY SYSTEMS
The heavy phase from the peel oil first-stage centrifuge is usually recirculated to extractors as “yellow water”. Part of this flow (10 to 50 %) needs to be replaced with fresh water in order not to concentrate too much insoluble material like pectin present in this poor oil emulsion before it’s sent back to the juice extractors. The nonrecirculated fraction of the yellow water has some residual oil content (0.5–1.0 %) that, instead to be sent to the feed mill or waste water treatment, is separated using specific equipment dedicated to recovering the residual oil. A traditional d-limonene recovery system heats the yellow water and further vaporises a mixture of water vapour and d-limonene in one or more inseries flash chambers. The vapour is subsequently condensed to recover the terpenic fraction. A more efficient new design eliminates the individual flash effects by incorporating a specially designed fractionation column to perform the vapour enrichment. This results in better d-limonene quality and yields, and a more compact recovery unit. Both systems can usually be fed with sludge discharge from the first-stage centrifuge as well as from the polisher (second-stage) centrifuge in the peel oil recovery unit.
5.8.3 THE WINTERISATION PROCESS
The polished oil contains trace amounts of dissolved wax derived from the peel of the fruit. At temperatures above 15 or 20 °C, the wax is totally dissolved. However, at lower temperatures it may give a haze to the product. To avoid this problem the polished oil is dewaxed, or “winterised” as it is called.
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5.9 Feed mill operations
Peel, pulp, rag and seeds from extractors
Hammer mills
Fig. 5.21 Flow chart of feed mill operations.
Reaction screws Lime
Peel presses
Static screens
Reaction screws
Press liquor tanks
Peel presses
Waste heat evaporator
Peel drier
Pelletiser Molasses tanks
Silo storage
d-Limonene tank
5.9 Feed mill operations
Feed mill process steps
After extraction of juice, about 50 % of the fruit remains. Much of this residual fruit matter is seemingly low-grade material in the form of peel, rag, core, seeds and pulp not used for commercial purposes. This waste is sent to a feed mill installed in most larger processing plants. Feed mill operations (see Figure 5.21) represent a significant part of the total plant running costs. The drying of solids and evaporation of the liquid stream are energy-intensive. Less waste and increased recycling of liquids in other parts of the plant are desirable for both economical and environmental reasons. Legislative pressure for environmental control in citrus plants continues to increase. The revenue from the sale of by-products from the feed mill makes a significant contribution to the overall profitability of orange processors. There is continuous development in finding additional products that can be recovered from peel and other waste streams.
The feed mill receives rejected fruit from the grading tables in the reception area and waste material from juice processing. The overall moisture content of this combined material is about 80 %. It is conveyed by screw conveyors to the wet peel bins of the feed mill. From here it is broken down to small pieces by hammer mills. Small amounts of lime (0.15 to 0.25 %) are added after this step to aid the dewatering process. After a dwell time of 10–15 minutes the mixture is conveyed or pumped to the peel presses. In the primary peel presses some 10 % of the moisture is removed. Continuous screw presses have largely replaced hydraulic batch presses for this task. Further addition of lime and secondary pressing can remove 2 or 3 % extra moisture. The liquid from the presses, press liquor, contains approximately 9–15 % soluble solids, much of which are sugar solids. The oil content can be between 0.2 to 0.8 %. The press liquor normally flows over static screens to remove peel solids and then on to the waste heat evaporator.
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5.10 Pulp production
In the past, most pulp went to pulp washing and the feed mill. However, now that the current market trend is to add more pulp cells to the final juice, the proportion of pulp from the extractors going to commercial pulp production is increasing. For most processors, however, more pulp is obtained from the fruit than is required by the juice industry for add-back to juice. The extractor type and operation will influence the quality of the pulp produced. In some plants, the extractors used for pulp production are adjusted to optimise pulp quality rather than to maximise juice yield. The visual difference between pulp from reamer-type extractors (Brown) and standard squeezer-type extractors (FMC) is illustrated in Figure 5.22.
The press liquor is usually concentrated to 50 °Brix and added back to the peel residue prior to pressing. Alternatively, it may be concentrated up to 72 °Brix and used as raw material for a fermentation process to make citrus alcohol. The press liquor contains a high amount of suspended materials and often includes sandlike matter. When decanter centrifuges are used for clarifying the press liquor, they should be equipped with special internal tiles to minimise erosion. Clarification of the press liquor can prolong the running time of the waste heat evaporator and reduce cleaning time substantially, thereby contributing to greater cost-efficiency in running the feed mill. d-Limonene is stripped off in the waste heat evaporator and can be recovered as a separate stream from the vapour phase. The pressed peel is dried in a rotary drier to a moisture content of about 10 % and then pelletised to make animal feed. The vapour that comes from the peel drier is used as heating medium in the waste heat evaporator.
5.10 Pulp production Floating pulp, i.e. the larger solid particles in the juice, mainly consist of small pieces of ruptured cell sacs and segment walls. They are separated from the juice in finishers. (The very small pulp particles flow with the juice stream from the finisher. These fine particles tend to sediment at the bottom of the juice and are referred to as sinking pulp.) The pulp stream from the finisher is handled in different ways depending on the end use of the pulp. The alternatives are: • Recovery for production of commercial pulp. Pulp is used as add-back in juice and juice drinks. • Production of pulp wash, the juice sugars obtained by washing pulp with water. The remaining material is sold as “washed pulp” or taken to the feed mill. • Routing to the feed mill for drying into pellets for animal feed.
Standard squeezer-type extractor
Reamer-type extractor
Fig. 5.22 Illustration of relative pulp sizes after extraction.
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5.10 Pulp production
TABLE 5.1 INFLUENCE OF PROCESS CONDITIONS ON PULP PROPERTIES Pulp properties
Process conditions
Cell length and fragmentation degree
-
fruit variety and fruit maturity size of the holes in the strainer tube (squeezer-type ex tractors) extraction pressure use of paddle or screw finisher back-pressure applied to the primary and final finishers (screw type) equipment and operating conditions for the pulp stabilisation step.
Oil content
- extraction pressure. High pressure gives higher juice yield but also higher oil content in the pulpy juice stream.
Defects in final product - depends on what type of equipment is used to separate defects from the pulpy juice stream. Pulp concentration (i.e the concentration of pulp particles in pulp slurry)
- tightness applied in the finishers.
5.10.1 PRODUCTION FACTORS WHICH AFFECT COMMERCIAL PULP QUALITY
Extraction
During the juice extraction process, segment walls and cell sac walls are torn into pieces. Both the reamer-type extractor and specially designed squeezer-type extractor used for premium pulp put less shear force on the pulp compared with the standard squeezer-type extractor. This results in larger and less fragmented pulp pieces. However, defects such as core and seeds also end up in the pulpy juice from the extractors. This imposes greater demands on the defect removal system. Sometimes, pulp from the primary finishers in juice clarification is conveyed to feed the pulp production line. Dilution with juice prior to defect removal may then be required.
Some of the process conditions which have a significant influence on pulp properties are given in Table 5.1. 5.10.2 PROCESS STEPS IN PULP PRODUCTION
The exact configuration of the pulp line will vary from plant to plant, and its design will depend on the type of extraction system and processor preference. The basic pulp production steps are shown in Figure 5.23. Instead of pulpy juice from the extractors, pulp from the primary finishers in juice clarification is sometimes taken as feed to the pulp production lines. Dilution with juice prior to the defect removal step may then be needed.
Pulpy juice from extractors
Defect removal
Reclaimed juice to evaporator
Primary finisher
Fig. 5.23 Pulp production steps.
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Pasteuriser
Drying finisher
Aseptic bag filler
Box/drum filler
Aseptic pulp chilled storage
Frozen pulp storage
5.10 Pulp production
through the underflow orifice while the majority changes its direction and flows upward to the cyclone overflow, taking an inner spiral path. If the density of the particles is higher than that of the liquid, the centrifugal force presses the particles against the cyclone wall from where they are pushed down and out through the bottom opening. Separation in a cyclone is improved with lower solids concentration and lower liquid viscosity. As small immature seeds are lighter than pulp slurry they are difficult to remove. Thus the quality of fruit delivered to the processor is important for the results of defect removal.
Cleaned pulp slurry
Pulp slurry
Fig. 5.24 A hydrocyclone used for removing defects.
Concentration (primary finishers)
The “cleaned” stream from the defect removal system is normally concentrated prior to heat treatment. The reasons for this are two-fold: • energy is saved by heating/chilling less product • less juice is subjected to additional heat treatment
Defects stream
Defect removal
Defects are normally described as small fragments of peel, membrane or seed. As the absence of defects in the final product is an important quality parameter, they have to be removed from the pulp/juice slurry. Defects are removed in a series of separation steps. The first step may be a classifying finisher. This is a paddle-type finisher incorporating screens with large perforations that will allow juice and cells to pass through but retain large seeds and pieces of membrane. The pulpy juice stream then goes to one or more hydrocyclones. If there are a lot of defects, two or more hydrocyclones are used in series. Hydrocyclones are based on gravity separation and remove defects which have a higher density than the pulp slurry. Figure 5.24 shows the liquid and particle flow in a cyclone. The infeed, which is tangentially introduced into the cone, starts moving in a downward spiral along the cyclone wall. As it nears the cone outlet, some of the product leaves
Concentration is done in a screw-type or paddletype primary finisher. Paddle finishers treat pulp particles more gently. The operation of the finisher can be adjusted so that the pulp concentration of the discharged pulp slurry is at the required strength for the downstream pasteurisation step. In Florida, most processors operate so that the pulp slurry from the primary finisher has a typical pulp concentration of 400–500 g/l. In Brazil, there is a difference between plants – from 150-200 g/l up to 500 g/l pulp concentration. The lower range is due to using plate heat exchangers in the pasteuriser. The pulp stream from the primary finisher to pasteurisation cannot be kept constant, but will vary in both flow rate and pulp concentration (10–15 %) during a production shift. Over a season, different fruit varieties and extractor settings will give wider variations.
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5.10 Pulp production
Heat treatment
The two objectives of pulp slurry pasteurisation are: • to inactivate enzymes • to destroy relevant microorganisms
enzyme concentration is “The higher in pulp slurry than in clarified juice
”
The necessary degrees of enzyme inactivation and microbial reduction depend on how the pulp will be further processed and stored. The required inactivation determines the pasteurisation conditions (temperature and time). As the enzymes in oranges are located in the fruit cell walls, the enzyme concentration is significantly higher in pulp slurry than in clarified juice. To achieve complete inactivation of enzymes, more intensive heat treatment is needed for pulp slurry than for juice. However, complete enzyme inactivation is normally not required. Enzyme activity should be reduced to such an extent that the pulp: • is stable during bulk storage • will not lead to cloud separation in reconstituted juice
Which heat exchanger?
The heat exchangers used for pasteurisation of pulp slurry are typically of tubular type. Any obstructions on the product side, such as contact points in a plate heat exchanger, should be avoided. Often the heat exchangers incorporate a single product tube. With this type there is no risk of uneven product flow. However, throughput is limited due to the pressure drop. A multitube heat exchanger (see Figure 7.12) can process high pulp flow rates without the drawback of excessive pressure drops. The inlet to the parallel tubes requires careful design to ensure that pulp does not stick to tube entrances thereby causing blockage and uneven flow rates through the tubes. Heat treating pulp at concentrations much above 500 g/l is not really feasible in tubular heat exchangers because heat transfer coefficients rapidly decline above this concentration. Efficient heat transfer is inhibited by the high cellulose content of the product. If tubular heat exchangers are used for higher pulp concentrations, they become very large, which entails slow heat-up and cool-down times resulting in a loss of product quality. A pasteurisation system for pulp using multitube heat exchangers can also have the dual function of pasteurising NFC. The nature of the pulp recovery process tends to entrain air into the product stream. This has to be considered in the design of the heat treatment process.
If the downstream handling of heat-treated pulp is nonaseptic (e.g. the drying finisher), complete killing of microorganisms is not required. This is the case for pulp stored frozen, the most common storage method. In this case the heat treatment is referred to as “stabilisation”. Typical heating conditions are 90–100 °C for 30 seconds. When pulp is to be stored chilled in aseptic bagin-box containers, heat treatment may be referred to as “pulp stabilisation/sterilisation”. Temperatures in excess of 100 °C are normally used. A higher degree of enzyme inactivation is required for chilled storage compared with frozen storage. Aseptic storage also requires that heat-treated pulp has no microbial activity. Furthermore, downstream equipment must not recontaminate the product.
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5.10 Pulp production
Pulp Pulpfrom fromjuice juice clarification clarification
Multistage counter current wash system
Pulp wash heater
Washed pulp
Water
Enzymes
Pasteuriser
Box/drum filler
Drum filler
Evaporator
Blending
Orange juice concentrate
Enzymatic reactor
Evaporator feed tanks
Clarifier
Debittering
Fig. 5.25 Flow chart of pulp wash production.
Concentration (drying or final finisher)
Packing in aseptic bag-in-box containers for chilled storage
Traditionally, the heat-treated pulp is further concentrated up to 950–1,000 g/l using a final or drying finisher. Although still wet it is called “dry” pulp because it will not release any free liquid when pressure is applied to it. The residual liquid is mainly adsorbed onto the cellulose membranes. The concentration of dry pulp is measured for product specification by a special method called Quick Fibre (described in Section 8). The liquid in the pulp, essentially NFC, typically cor responds to 5–8 % of pulp mass for standard pulp, and 9–13 % for premium pulp. Thus when pulp is added during reconstitution at the juice packer, the juice still present in the “dry” pulp will provide additional NFC.
If the stabilisation process is modified to become a stabilisation/sterilisation process, it is possible to pack pulp aseptically and store it refrigerated. Packing is done directly after heat treatment. Hence, the aseptic pulp will be bulk stored at a much lower concentration than frozen pulp. The disadvantage of packing pulp aseptically at 500 g/l concentration is that a larger storage (and shipping) volume is needed for the same amount of dry pulp. The advantage is that the pulp is much easier to handle as it is pumpable and needs no thawing or crushing. It also gives the possibility of enhancing the final product. When the aseptic pulp is added back to juice reconstituted from concentrate, juice present in the aseptic pulp (effectively NFC) may provide some of the desired flavour associated with NFC products. Aseptic pulp is produced by several processors in Florida.
Packing in boxes/drums for frozen storage
The concentrated pulp is normally packed in 20 kg corrugated cardboard boxes lined with a polyethylene bag which are then frozen. Freezing can take several days. Pulp may also be packed in drums (200 l/55 gal.) for frozen storage. However, drums are not often supplied to juice packers as they are usually too large for the batches of reconstituted juice.
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5.11 Pulp wash production
The high content of pectin in pulp wash leads to a greater increase in viscosity during evaporation compared with pure juice. This can lead to a limit of 40 °Brix for pulp wash concentration. Therefore, breaking down pectin by enzyme treatment is often included in the pulp washing process. Typical conditions are a retention time of up to one hour at 45 °C in the reactor tank. After centrifugation, enzyme-treated pulp wash can be concentrated to the normal 65 °Brix level and then blended with orange juice concentrate or packed in 200 l drums and frozen.
5.11 Pulp wash production Pulp washing is carried out to recover juice solubles in pulp coming from the juice finishers and from the centrifuges in the clarification or deoiling process. Thorough pulp washing can increase the total yield of soluble solids by 4–7 %, which contributes significantly to overall plant economics. The process steps are shown in Figure 5.25. The juice sugars are reclaimed by a countercurrent washing system. The pulp/water slurry is strained through a finisher between the washing stages and the separated “juice” is called pulp wash. Process development includes the use of static mixers to blend and allow equilibrium of soluble juice and pulp components during washing. The pulp stream is concentrated by evaporation. It is added back to concentrated orange juice (if the law permits) or used as a base for juice drinks.
Washed cells
Washed cells can either be sent to the feed mill or be bulk packed in 25 kg cardboard boxes or 200 l drums which are stored frozen. The product is traded as washed pulp or washed cells and used in some drink applications. Regulations for and use of pulp wash
washing can increase “Pulp the total yield of soluble
Pulp wash is often used as a source of fruit solids in formulated beverages and juice drinks, and as a clouding agent for providing body and mouthfeel. Pulp wash may be included in orange juice concentrate in Brazil and Florida provided that it is produced along with the juice extraction process. In Florida, pulp wash addition is limited to max. 5 %. Nevertheless, the quality standards and marketing approach of some processors or organisations may still preclude the addition of pulp wash. While the previous Fruit Juice Directive of the European Union did not allow a product containing pulp wash to be called orange juice, the new Directive of 2001 allows in-line water extraction of pulp for the production of orange juice concentrate. Pulp wash is also referred to as water-extracted soluble orange solids, WESOS.
solids by 4–7 %
”
The number of stages in a pulp washing system is chosen according to cost-effectiveness. A maximum of four stages can recover up to 50 %, 63 %, 75 % and 80 % respectively of the available juice sugars. The amount recovered depends on the water to pulp ratio as well as fruit variety and maturity. Debittering and enzyme treatment
Pulp wash is high in limonin, which causes bitterness. Consequently, nontreated pulp wash has limited use as add-back into high quality juice drinks. However, the bitter taste can be removed by a debittering process involving ultrafiltration and adsorbing separated bitter components onto resin.
5.12 Essence recovery Essence recovery is an integral part of the evaporation process and is described in the section on concentrate production.
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6
Transport and handling of bulk products
In section 6 you will read about: • Which packing and shipping methods are preferred for orange juice products. • The alternative ways bulk FCOJ is shipped over land and sea. • What happens to bulk FCOJ en route from Brazil to Europe. • How overseas shipments of frozen and aseptic NFC are handled.
• The advantages of shipping NFC in bulk rather than in retail packages. • The factors that determine shipping costs. • Dedicated terminals for receiving bulk FCOJ and NFC. • Operations carried out by blending houses.
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6. Transport and handling of bulk products FCOJ Tank car frozen
Terminal frozen
Bulk tanker frozen
Terminal frozen
Tank car frozen
Truck frozen/chilled
Terminal frozen/chilled
Cargo vessel frozen/ambient
Terminal frozen/chilled
Truck frozen/chilled
Tank car chilled
Terminal aseptic chilled
Bulk tanker aseptic chilled
Terminal aseptic chilled
Tank car chilled
Fruit processing plant FCOJ/NFC
NFC
Fig. 6.1. The transport chain for the bulk shipping of orange concentrate and NFC.
Juice packers
Soft drink producers Blending house
Chilled/frozen transport
Receiving and blending juice Shipping costs depend on the modes and current rates of shipment. The sales price for the bulk product usually includes the cost of the bulk package, and often the transport costs to the import harbour. Dedicated terminals for bulk FCOJ are found in Brazil and major juice importing regions. Some terminals now also have facilities to handle bulk NFC under aseptic conditions. Products in storage tanks are under nitrogen atmosphere to protect them from oxygen. Operation of a terminal needs to be controlled by a modern automation system. Blending houses supply concentrates (and NFC products) of defined and consistent quality to juice packers. A wide range of raw materials are used to prepare the concentrates and bases, often made to customer-specific recipes.
SUMMARY Shipping of orange juice products is dominated by bulk shipments, mainly frozen concentrate. In Florida, bulk not-fromconcentrate juice (NFC) is moved between processors and to packers in other states. However, significant quantities of NFC is filled into consumer packages in Florida before distribution. Frozen concentrate is shipped in tanker ships, conventional cargo vessels, railway tanker wagons, road tankers and drums. Some concentrate is filled into aseptic bagin-box containers. Transporting FCOJ from Brazil to Europe is now a very streamlined, cost-effective and time-saving process. Bulk NFC is stored chilled under aseptic conditions or frozen. Aseptic product may be shipped under chilled or non-refrigerated conditions. Special ships with refrigerated aseptic tanks transport NFC from Brazil to the US and Europe. Shipping bulk NFC for retail packing in overseas consumer markets is more economical than shipping NFC products in retail packages.
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6.1 Packing and shipping preferences
6.1 Packing and shipping preferences
6.2 Bulk shipping of FCOJ Notable developments in the transport systems followed the large expansion of concentrate exports from Brazil in the 1970's and 80's. Shipping of orange concentrate is done in tanker ships, road tankers and drums. For shipping in tankers, the product is typically kept at –8 to –10 °C. For drums, the product is commonly packed in 200 l (55 gal) steel drums with double polyethylene liners and stored frozen at –18 to –25 °C. Some concentrate, in limited quantities, is also packed in aseptic bags using drums or wooden bins for outer support. Aseptic bags of concentrate are typically put into frozen or chilled storage at the producer site. However, as aseptic bags do not require frozen conditions, they allow more flexibility – and possible cost-savings – in the transport chain. In some markets, frozen conditions cannot be guaranteed throughout the entire transport chain. Alternative ways of transporting concentrate by land and sea are listed in Table 6.1.
Orange juice consumption in Europe, the Far East and the USA (with regard to imported Brazilian juice) requires shipping large quantities of juice products over long distances. Transport costs constitute a significant part of the bulk product price, typically 15–20 %. Hence, efficient control of the transport chain is important. Outside the US market by far the dominant product shipped is bulk frozen concentrated orange juice, FCOJ. Although overseas exports of not-from-concentrate orange juice, NFC, are increasing, they are still relatively small on a global scale compared with FCOJ shipments. When NFC is shipped overseas it is predominantly in the form of bulk product, either frozen or aseptic bag-in-box. Dedicated ships fitted with bulk tanks also now transport NFC under aseptic chilled conditions from Brazil to the US and Europe. Long-distance overseas shipping of juice products in retail packages is not common for reasons of cost and logistics. However, some Florida juice and some juice products from South Africa, Australia and elsewhere are exported overseas in retail packages. In the US market the situation is different. Most orange juice is produced in Florida, followed by California, and the area of largest juice consumption is northeast USA. Some ready-todrink juice is reconstituted from concentrate and packed in retail packages at the processors in Florida, although most is transported as bulk FCOJ to packing plants around the USA. NFC in liquid bulk form is transported chilled by road and rail tanker in Florida and to juice packers in other parts of the USA. Nevertheless, the majority of Florida NFC is still packed in consumer packages at fruit processing sites and distributed by truck or train under refrigeration. Frozen concentrate for home dilution is still a common retail product in the USA. It is retail packaged (typically in 12 ounce composite can) in Florida and distributed frozen. The international transport chain for bulk orange product is shown in Figure 6.1.
TABLE 6.1 DIFFERENT WAYS OF TRANSPORTING CONCENTRATE Land transport at producer and receiving end - Road tankers - Frozen drums in refrigerated trucks - Aseptic bag-in-drum in refrigerated or dry container - Railway tanker wagons Overseas shipping - Tanker ships - Drums as frozen break bulk - Drums in refrigerated containers - Aseptic bag-in-drum in refrigerated or dry container
The transport of FCOJ in bulk tanker ships is made easier by special port terminals. Such dedicated quayside facilities can now be found in the major export and import regions for orange concentrate, such as New Jersey, Western Europe and Japan. The major Brazilian processors have built their own terminal facilities in Brazil, Europe and Japan.
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6.1 Packing and shipping preferences
Today there are a number of large tanker ships which have been constructed solely for transporting FCOJ and other citrus products in bulk. Tanker capacities are in the range of 6,000 to 15,000 tonnes of product. Some of the major Brazilian processors run their own ships for bulk orange product. Drummed concentrate can be shipped in conventional cargo vessels. Two common ways of shipping FCOJ in drums are as “break bulk” and in freight containers. With “frozen break bulk”, the drums are loaded individually into a refrigerated compartment in the vessel. Alternatively, drums (often on pallets) are put into “refrigerated containers” (reefers) which are loaded into the ship. At the importing end the same container can be used for land transport by truck to the end user.
Nevertheless, drums are likely to remain the most appropriate shipping container for smaller producers, regions with low production levels, special quality concentrate, etc. 6.2.1 FROM BRAZIL TO EUROPE
Today, from a logistical standpoint, transporting FCOJ from a production site in Brazil to a European juice packer is a very streamlined, cost-effective and time-saving process. Most orange production in Brazil takes place in the state of São Paulo. The distance from the fruit processing plants to the export harbour, Port of Santos, is 400–800 km. The FCOJ is transported to Santos by road tanker, and a continuous fleet of dedicated trucks can be seen around the clock making the journey to and from Santos. When unloaded from road tankers, the product is stored in dockside tanks at –10 °C under nitrogen atmosphere. The scheduling of the orange concentrate vessels is precisely controlled. As soon as the bulk tanker ship arrives at Santos, the stored product is pumped on board. Total loading of a ship is completed within 24–36 hours. The ship’s tanks are filled completely to allow little or no headspace. The crossing to Europe typically takes 13 days. En route the product and its environment are continuously monitored. The ships arrive in Europe at ports with dedicated dockside facilities to receive FCOJ. Large positive displacement pumps (for 8 inch piping) on board the ship pump out the FCOJ directly into storage tanks on land. Unloading a full vessel can be done in 24–36 hours. After unloading, the ship takes in ballast and starts its return voyage to Santos. The ship may also take freight containers on deck for the return voyage. Except for the transport by road tankers in Brazil, juice concentrate is maintained under nitrogen atmosphere from processing plant storage to European terminal storage. For the return trip to Brazil, the ship’s empty tanks are not cleaned out but kept under nitrogen.
TYPICAL SHIPPING CONTAINERS Refrigerated container (reefer) An insulated container with a refrigeration unit which can be set at the desired temperature (chilled or frozen). Dry container A regular container for transportation at ambient temperature or under non-refrigerated conditions.
Shipping rates are lower for break bulk than for refrigerated containers, but drums in break bulk require more handling at the exporting and importing ends. The handling of FCOJ in bulk tankers requires heavy investment in infrastructure such as ships and special dockside terminals. When these are in place, however, it is a more efficient way of transporting large product volumes compared with drums or returnable containers. The total cost for drum transport should take into account both the cost of manufacturing or reconditioning drums and possible charges to dispose of the drums. There is often no use for the drums in the importing region, in which case the juice packers must pay to dispose of them.
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6.3 Bulk shipping of NFC
6.3 Bulk shipping of NFC There are two alternative ways of storing bulk NFC – chilled under aseptic conditions, or frozen. Also, shipping of aseptic product is usually carried out under chilled conditions, although sometimes refrigeration is not used. Frozen (nonaseptic) product must be transported under freezing conditions. Unlike concentrate, which is still pumpable when frozen although it is highly viscous, NFC freezes solid. Because pumping frozen NFC into or out of tanks is impossible, it must be frozen, stored and transported in individual containers. The expansion of NFC production in Brazil at the end of the 1990's led to the development of bulk sea transport for chilled aseptic NFC.
Fig. 6.2 Wooden bin and drums for aseptic bags.
6.3.2 BULK UNITS FOR ASEPTIC NFC SHIPMENTS
6.3.1 FROZEN NFC SHIPMENTS
For frozen shipments, NFC is usually filled into 200 l (55 gal) drums with plastic inner liners. It takes several days or even weeks for NFC in drums to freeze solid. Larger unit sizes would be desirable for economical reasons, but the technology for quick freezing/thawing of larger unit sizes of NFC for shipping has not gained wide commercial acceptance. Single-strength juice starts to freeze at around –2 °C. Freezing of NFC in drums does not occur homogenously throughout the product. As water forms ice crystals, a gradually more concentrated juice solution is left behind with an accompanying slow decrease of the freezing point. The reverse process occurs when the product thaws out in drums. As a result, the first melted portions have a lower °Brix content than completely liquid juice. Freezing causes NFC to expand, thus standard 55 gal drums are typically filled with NFC to only 45 gal. As with drummed FCOJ, NFC in drums is shipped as frozen break bulk or in refrigerated containers.
There are several different types of bulk units for shipment of aseptic NFC. The one tonne aseptic bag-in-box units are the most commonly used. The units are normally shipped in freight containers, either refrigerated or dry. The aseptic bags are multilayer plastic bags with a barrier layer – normally aluminium foil – to minimise oxygen ingress during storage and transportation. The bags require an outer support, usually a bin made of wood or cardboard. The wooden bins are collapsible and returned for reuse (see Figure 6.2). The cardboard bins are normally used only one-way. The dimensions of the bins are chosen so that they can be efficiently stacked into the freight containers used. The unit size may therefore vary between different bag-in-bin users, but lies typically in the range 900–1,200 l (240–320 gal). There is little or no headspace in the bags. Stringent demands must be placed on the integrity of aseptic bags used for NFC. It is a liquid that flows freely inside a bag restrained by an outer support, unlike, say, tomato paste which is highly viscous and hardly moves. Whether chilled or ambient conditions are used, asepticity must be maintained throughout the transport chain because reinfection of an individual bag may lead to blowing of the bag. Therefore the good handling procedures in common practice today must be followed closely.
juice starts “Single-strength to freeze at around -2 °C ”
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6.3 Bulk shipping of NFC
Extracted juice
Frozen route
Aseptic bag-in-box route
Aseptic bulk sea vessel route
Pasteurisation
Pasteurisation
Pasteurisation
Packing in lined steel drums
Packing in aseptic bag-in-box
Aseptic chilled storage at port
Freezing
Aseptic transfer to bulk tanks on ship
Frozen storage
Chilled storage
Frozen transport
Ambient transport
Chilled transport Aseptic unloading to dockside tanks
Thawing and crushing Blending and repasteurisation
Aseptic transfer (or blending and repasteurisation)
Chilled transport by road tanker
Retail package filling
Retail package filling
Blending and repasteurisation Retail package filling
Fig. 6.3 Different handling routes for NFC.
When a product is required at the juice packer, NFC is emptied from the aseptic bag either by cutting open the bag and removing the juice with a hose pump placed inside the bag, or by pumping out the product through a separate emptying spout (controlled emptying). Alternatively, with an aseptic unloading station, juice can be pumped out from the bag under aseptic conditions followed by aseptic transfer to retail packaging. As product sterility is maintained, the juice does not need to be repasteurised prior to retail packaging. The handling and processing steps for NFC via the frozen route and the aseptic bag-in-box route are shown in Figure 6.3. Aseptic totes are an alternative to aseptic bagin-box containers. The totes are mobile stainless steel tanks (1,000–3,000 l product volume). They are steam-sterilised and pressurised with nitrogen
before filling. They may be used for the storage and transport of NFC. However, totes are mainly used for short-term storage and transport over short distances because of the high investment and freight costs (including return freight) involved. Much larger juice quantities can be packed in aseptic transport containers. These are mobile aseptic tanks of 20,000 l (5,000 gal) or more and of varying designs. Some are built inside a freight container and transported as such; another design takes the form of self-contained tanks sized to fit into trucks, ships and trains. Aseptic transport containers can also be used for on-site storage of juice product before it is shipped from the processing plant. Although the large unit sizes of transport containers provide better economy of scale for handling aseptic NFC, the cost risks associated with faulty operation or unsterile juice are much larger.
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6.3 Bulk shipping of NFC
6.3.3 BULK SHIPPING OF ASEPTIC NFC BY SEA
in the port facilities “Investments provided the technical solutions required to integrate juice storage with aseptic shipping conditions
While NFC (single-strength orange juice) produced in Florida is mainly packaged locally or delivered overland to juice packers in the rest of the US and Canada, NFC from Brazil and other regions is mainly destined for bulk export overseas. During the late 1990’s, the desire to increase the export of NFC orange juice from Brazil by sea led to advances in technologies enabling the integration of NFC seasonal storage and export by bulk sea vessels. This now facilitates the efficient handling and shipping of large volumes of bulk NFC from Brazil to the US and Europe. The major Brazilian juice producers are very large companies that have developed the logistics expertise needed for large-scale operations. They have their own port terminals and for many years have run a fleet of “citrus” tankers dedicated to shipping frozen concentrated orange juice. Today, some companies also have aseptic storage capacity at ports for exporting NFC instead of at their processing plants. After extraction at the processing plant, prepasteurised juice is cooled to 0 °C and then transported by insulated road tanker (25 tonnes) to the dockside storage facilities. And after final pasteurisation, the juice is stored in enormous aseptic tanks each of nearly 4 million litres volume (1 million US gallons) until exported. The aseptic tanks are located in insulated refrigerated storage areas where the temperature is maintained at 0 °C. Investments in the port facilities provided the technical solutions required to integrate juice storage with shipping conditions. Initially, existing ships were rebuilt for transporting bulk aseptic NFC, but in the early 2000’s new ships were built and launched specifically for carrying NFC along with FCOJ. These new ships can take up to 35,000 tonnes of FCOJ and NFC each. They are more than 200 m long (about the length of two soccer pitches) and 30 m wide. Each ship contains four insulated refrigerated holds with several freestanding cylindrical tanks in each hold. Some tanks are dedicated to NFC and others can carry either frozen concentrate or NFC. Sloping bottoms ensure that the tanks can be completely drained.
”
The orange concentrate is loaded and transported at –10 °C while NFC is shipped at a nominal 0 °C. Individual bulk tanks are maintained under continuous nitrogen pressure, even during loading/unloading when nitrogen is exchanged with dockside tanks. For the return trip to Brazil the empty tanks are filled with nitrogen. Each ship is equipped with its own sterilisation system for the bulk tanks, and the piping system is sterilised before juice transfer. Aseptic seals are maintained on tank valves throughout the journey. The import terminals have special facilities to allow aseptic unloading of NFC and routing it to dockside aseptic storage (see section 6.5.2). To reduce the costs of empty return voyages, the citrus tankers can also take on-deck freight containers (dry and refrigerated). Although these dedicated ships and specially equipped terminals require large investments, they result in more cost-effective storage and transport of large NFC volumes. 6.3.4 TRANSPORT OF BULK PRODUCT VERSUS RETAIL PACKAGED PRODUCT
For concentrate, it is obvious that bulk shipping is more cost-effective than shipping reconstituted juice in retail packages because shipping volumes are 5–6 times smaller with concentrate. For NFC, however, the volumes are about the same whether shipped in bulk or retail packages. Nevertheless, for long-distance overseas transport, shipping of bulk product for retail packing in the consumer market provides economical advantages. Bulk packaged NFC can maintain a long shelf life, whereas after retail packaging in nonaseptic packages its shelf life is relatively short. A month of the shelf life in retail packaging is eliminated by the transport chain. Shipping of retail packages requires additional outer packaging to protect the packages. In addition, it is not possible to respond quickly to market demands due to the long lead time required to get retail packages to the consumer.
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6.4 Shipping 6.4 Shipping costs costs
6.4 Shipping costs
6.5 Terminals for receiving orange juice
Shipping costs for bulk packages depend on the method of shipment and the rates applicable at the time of shipment. The following factors should be taken into account in estimating total shipping costs: • type of bulk package • transport to the export harbour • handling at the export harbour • sea freight • handling at the import harbour • transport to the juice packer(s)
6.5.1 TERMINALS FOR BULK FCOJ
The product sales price usually includes the cost of the bulk package, and often the transport costs to the import harbour (e.g. cif Rotterdam). The rates for sea freight depend on current supply and demand, and may vary significantly over time. For product which can be stored, shipment planning aims for periods of low freight demand and hence lower rates. Generally, rental rates for refrigerated containers are double those for regular (dry) containers. Calculated per tonne of product, freight costs for frozen break bulk (in 200 l drums) are between the respective costs for refrigerated and dry containers. Rates for 40 ft containers are typically 20–40 % higher than rates for 20 ft containers. Although 40 ft containers provide twice the shipping volume, their maximum weight load is typically 26 t compared with 20 t for 20 ft containers. In assessing the alternative giving the lowest shipping cost per tonne product, weight limitations need to be taken into account. The density for single-strength juice, such as NFC, is about 1.04 t/m3 but about 1.3 t/m3 for concentrate. Moreover, drums make less efficient use of shipping volume than rectangular bins. For this reason, drums of frozen NFC are usually shipped in 40 ft containers because a 20 ft container would not reach the maximum weight limit when fully loaded.
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Dedicated terminals for receiving bulk frozen concentrate are found in large ports in the Netherlands (Amsterdam, Rotterdam) and in Belgium (Ghent, Antwerp). Such terminals are also found in Florida, New Jersey and in a few major ports in Japan. Below, an example of a terminal (Ghent in Belgium) equipped to handle bulk FCOJ from a tanker ship is described with reference to Figure 6.4. From the tanker ship, orange juice products are pumped into six reception lines which feed the 34 storage tanks on land (the largest of which has a capacity of 2,000 tonnes). From bulk storage in the tank farm, the juice products are pumped to six blending stations. Here concentrates of different types are mixed to ensure that products meet customer specifications. Peel oil and other flavour fractions may also be added. The concentrate is then pumped to one or more of nine discharging lines used for filling road tankers for product distribution around Europe. In addition to concentrate, specialty products such as peel oil are also pumped from the tanker ship to storage tanks at the terminal, although in smaller volumes. A nitrogen system at the terminals is used to ensure that storage tanks always contain a nitrogen atmosphere, both when empty and when being filled with product from a tanker ship. The terminals normally also store large volumes of raw material and finished product in frozen drums. Raw materials from emptied drums are blended in the blending stations with concentrate from tank storage. Blended products are packed in drums and distributed frozen to juice packers. Operation of a terminal, as described in the example above, requires a practically unlimited choice of product routes. Therefore it needs to be controlled by a modern automation system which allows the operators to get a rapid overview of pumping operations at all times.
6.5 Terminals for receiving 6.4 Shippingorange costs juice
Reception lines
Tank farm
Blending stations
Discharge lines
Fig. 6.4 Terminal handling of FCOJ.
Drum storage/emptying
On-line communication of the control system with the scheduling and commercial departments is also important for this type of operation.
Drum filling
In a similar way to FCOJ terminals, a nitrogen system ensures that the entire system of tanks and piping is under nitrogen pressure during juice transfer. In the juice reception area there is a stand-by pasteuriser used when necessary to pasteurise incoming juice or the content of a storage tank. But in well-designed and well-functioning facilities, this emergency pasteuriser should never need to be used. Juice in dockside tanks is sampled regularly to verify that their contents are microbiologically acceptable. The juice from tank storage is dispatched by road tanker, hygienic but not aseptic, to juice packers. Blending of NFC may take place before dispatch (see section 6.6). At the juice packing plant, blending of orange juice and the addition of pulp may be carried out before repasteurisation and retail packing. At a NFC port terminal in Belgium, facilities for retail packaging of the juice are located at the same site, thereby eliminating the extra bulk road transport step and reducing the costs of delivering NFC juice products to consumers in Europe.
6.5.2 TERMINALS FOR BULK ASEPTIC NFC
NFC in frozen drums and aseptic bag-in-box bulk containers can be unloaded at standard terminals having refrigerated and frozen warehousing. However, special terminal facilities are required for NFC transported in bulk aseptic tanks on ships. In response to the use of bulk aseptic seagoing vessels, facilities for the aseptic unloading of orange juice were installed in Florida and Europe in the early 2000’s. In a similar way to juice export ports, aseptic storage tanks – usually in stainless steel – are installed at the dockside, but the total number of tanks and the size of individual tanks are smaller because storage is only required to cover production between ship arrivals. Before unloading the ship, juice samples from onboard tanks are checked to confirm that the juice is microbiologically acceptable. The piping system is sterilised before aseptic juice transfer from onboard tanks to dockside storage.
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6.4 Shipping costs
The design requirements for terminals handling bulk aseptic NFC are high. Operations are complex and much effort is spent in minimising the inherent high risks. Experience gained from aseptic processing plants and NFC storage facilities in Florida has been vital in the construction of European terminals. Modern control system and automated valve configurations ensure correct operation. On-line networking between all de-partments of dockside juice-handling facilities is also important to ensure smooth operations. And as with export terminals, initial investments are high, but once the installations are in place cost-effective handling of bulk NFC volumes results.
Sometimes the final product is pasteurised after blending but prior to distribution (e.g. in aseptic bags). More commonly, pasteurisation is not carried out but raw materials are maintained at low temperature (<0 °C) during blending and finished products are distributed frozen. Softdrink bases may include preservatives to make them shelf-stable. Strict quality hygiene control and cleaningin-place are indispensable to blending house operations. They are necessary to avoid an increase in microbial load on products, and to prevent a batch of juice of poor microbial quality from contaminating subsequent batches. Laboratory analysis plays an important role. Quality control procedures include authenticity testing of the wide range of incoming raw materials. Finished blended products also undergo testing to ensure they meet the agreed specifications. Blending procedures require specialist knowhow on the products manufactured and their intended use. This competence forms a valuable part of the service offered by blending houses to their customers, along with the development of proprietary recipes. Some of the FCOJ terminals also include the functions of blending houses and manufacture products according to customer specifications.
6.6 Blending house operations Blending houses supply concentrates (and NFC) of defined and consistent quality to juice packers. They also prepare bases for beverage producers. Products supplied from blending houses are often made to customer-specific recipes. A wide range of raw materials is used by blending houses to prepare the concentrates and bases, such as different fruit juice concentrates, flavour fractions, oils and pulps. High-volume fruit juices, such as orange and apple, are taken in from bulk storage tanks while other raw materials come in frozen drums, aseptic bags and various smaller containers. Normally, the orange products used by the blending houses come from a larger number of countries than those used by the terminals. Blending stations form the heart of blending operations. As at the terminals, blending of FCOJ and other very viscous concentrates requires very powerful mixers. Raw material supply to the blending units comes from tank storage, drum emptying and from drum crushing (if the product in the frozen state is not pumpable). After blending, the product is packed in drums or pumped into road tankers.
houses supply “Blending concentrates (and NFC) of defined and consistent quality to juice packers
”
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7
Processing at the juice packer
In section 7 you will read about: • Different aspects of the pasteurisation process, including choice of heat exchanger, deaeration and process control. • How buffer tanks ensure smooth filling operations and avoid product recycling. • Hot filling of nonsterile packages. • The aseptic transfer of NFC juice from aseptic bags to filling machines. • Cleaning-in-place (CIP) routines and the major parameters involved. • Quality control of the packaged product.
• An overview of different process lines at the juice packer. • In what form raw materials arrive at the juice packing plant and how they are handled. • The water quality required for juice reconstitution and water treatment methods. • The importance of accurate blending, and a comparison of different blending methods. • How Brix and density are measured and the relationship between them.
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7. Processing at the juice packer SUMMARY Juice packers process concentrate and NFC juice and fill the end product into consumer packages. Cost-efficient operation and gentle product treatment are essential. During raw material storage and handling, it is important to maintain conditions that prevent microbial growth in products. The quality of water used for concentrate reconstitution must be high. Water treatment methods aim to remove or destroy undesirable substances. Examples of these are organic matter, salts, chlorine and microorganisms. Reconstitution involves diluting one or a mix of different concentrates with water to the right Brix level. Although NFC juice is not diluted, NFC juices of different origins may be blended to produce juice with the desired properties. The more accurate the blending process, the greater the cost-savings achieved. In-line continuous blending offers advantages in certain respects compared with batch blending.
Tank car frozen
Maintaining juice quality Pasteurisation, with either plate or tubular heat exchangers, is carried out to destroy microorganisms in juice before filling. A deaerator may be included in the system. An aseptic buffer placed between the pasteuriser and the filling machine(s) smoothes product filling and increases production efficiency. In the hot filling method, hot product kills microoganisms on the surface of the nonaseptic container after filling. Effective CIP is essential for the high standard of hygiene demanded at the juice packer. The most suitable combination of temperature, time, type of detergent solution and flow rate is selected for a particular cleaning cycle. Quality control of the packaged product is determined by two prime factors, the properties of the juice and its microbiological status. Product sampling and analysis are regularly carried out, which also helps to define the processing conditions needed to maintain juice quality.
Storage
Blending tanks Truck frozen
Drum emptying
Pasteuriser
Buffer
Filling machines
Storage
Fig. 7.1 Juice packer operations.
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Distribution network
7.1 An overview of juice packer operations
7.1 An overview of juice packer operations
Gentler product treatment is promoted by process control, which allows close monitoring and control of operating parameters, and careful equipment design. To supply products at competitive prices requires cost-effective operation. High energy recovery that reduces heating and cooling costs, and minimising product losses in the plant, are two major ways of reducing operating costs. Together with reducing waste from cleaning procedures, these measures also minimise the impact on the environment. High-acid products put different demands on processing equipment compared with low-acid products like milk. Consideration must be given to the fact that fruit juices differ in viscosity and often contain particles (pulp). For both aseptic products and nonaseptically filled (chilled) products with long shelf life (>20 days), high hygiene standards and safety measures are applied to the pasteurisation process and downstream equipment in order to prevent any microbiological recontamination of the product. The juice packing plant is normally designed to process and package a range of fruit juices and juice-based still drinks. The equipment described in this section is not used only for processing orange juice. However, comments made regarding equipment requirements and performance relate to orange juice.
Juice packers take in bulk raw materials (concentrate and/or NFC), treat them and then fill the final product into consumer packages. Sometimes the distribution of packaged products is also carried out by the juice packer. Typical operating steps at the juice packer are illustrated in Figure 7.1. This section discusses the processing steps that take place in a juice packing plant up to the filling machine. Packaging activities are covered in Section 9, packaging and storage of orange juice, and the distribution of products to retailers is outlined in Section 10, from juice packer to consumer. Capacities of juice packing facilities vary greatly – from small plants producing 5,000 l/h packaged juice to large plants with an output exceeding 150,000 l/h. The larger facilities are built up of multiple processing and filling lines. One line of processing equipment can feed several fillers. Conversely, one filler can be alternately connected to several processing lines handling different types of product. Unlike the fruit processors’ seasonal yet nonstop operation, production at juice packers is year-round and typically involves 2–3 shifts/day, 5–7 days a week. Production throughput is not uniform throughout the year. Peak output occurs normally in the run-up to the summer months and the Christmas period.
7.1.2 PROCESS LINES
The process line from the reception of raw material up to product at the filler involves a number of process steps. Which steps are required depend on the type of raw material and product to be produced. Figure 7.2 illustrates the process steps for production of orange juice starting from frozen orange concentrate as raw material (Lines 1 and 2). Ingredient preparation for the production of orange nectar and fruit drinks is also included. In lines 3 and 4, the raw material is NFC.
7.1.1 GENERAL REQUIREMENTS FOR JUICE PACKER LINES
Pressure on juice packers from the market is steadily increasing. They are required to supply a wider choice of products, better quality and convenient packaging – at even more competitive prices. Increased product diversification means smaller volumes of each product. In turn, this demands greater equipment flexibility and plant designs that minimise product losses and downtime when products are changed. From a plant operation viewpoint, better product quality means avoiding overprocessing.
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7.1 An overview of juice packer operations Drink preparation
Water treatment
Concentrate storage and preparation
Batch blending
LINE 1 In-line blending
Concentrate storage and preparation
LINE 2
Concentrate storage and preparation
Concentrate received in tank cars is pumped into large storage tanks. The storage area is refrigerated or the tanks are equipped with cooling jackets. The concentrate should be kept at less than 0 °C. Concentrate received in drums is placed in frozen storage. From the storage tanks, concentrate may be pumped directly to the blending area for reconstitution with water. If concentrates of different origins or fruit types are to be blended, this may take place in a separate tank prior to dilution with water. Concentrate in drums is warmed up to –5 °C or higher before it is poured or pumped out. Water treatment
The required treatment of product water, used for diluting concentrate to final product, depends on
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the quality of water supplied to the plant. Treatment methods commonly used include sand filtration to remove insoluble solids, active carbon filtration to remove colour, and membrane filtration to reduce dissolved salts (and organic matter). Ion-exchange techniques may be used to soften the water or reduce its alkalinity. When there is high water consumption in a plant, e.g. during start-up and cleaning cycles, treated product water is routed to a buffer tank to ensure a sufficient supply. Batch blending
The reconstitution step, referred to as the blending step, is carried out batchwise in Line 1. The concentrate is diluted with water in large agitated tanks. A batch is prepared in one tank while product is pumped from another tank to pasteurisation after sampling to check Brix value. Pulp slurry
7.1 An overview of juice packer operations Cleaning in-place
Automation
Filling
Pasteurisation
Aseptic buffer
Pasteurisation
Aseptic buffer
Fig. 7.2 Processing lines using concentrate as raw material.
(and sugar solution for nectars and fruit drinks) are added in the batch tank along with the concentrate. Other ingredients may be added directly to the batch tank but are often prepared as a preblended mixture in the drink preparation area.
Pasteurisation and deaeration
In the pasteuriser, juice is heated in tubular or plate heat exchangers to pasteurisation temperature (80–95 °C), which is maintained as the product passes through the holding cell. The juice is then cooled to filling temperature and routed to the filler. Free air and dissolved oxygen are removed from the juice in a deaerator. Most of the heat used is recovered from cooling pasteurised juice and additional energy is supplied by circulating hot water heated by steam. During cleaning, start up, and any operating failure, the flow is recirculated over the pasteuriser.
In-line blending
In Line 2, treated water and concentrate (and other ingredients) are fed continuously to the inline blending system and mixed en route to the pasteuriser. The critical parameter, usually Brix of the final product, is monitored constantly. Flow rates of the respective components are adjusted by the control system to maintain the target Brix value. The total flow of blended product, routed via a buffer tank, is adjusted to suit pasteurisation capacity.
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7.1 An overview of juice packer operations
NFC frozen storage
Thawing and crushing
Blending and buffer
LINE 3 NFC chilled storage
Juice emptying
Blending and buffer
LINE 4
Aseptic buffer
Drink and nectar preparation
In most cases pasteurised product goes directly to the filler from where any overflow is returned to the pasteuriser. A buffer tank ensures that variations in filler operation do not affect upstream processing, and that continuous adjustment of pressure and flow can be made to suit the filling capacity. Buffer capacity is required for certain types of filler. Buffer tanks should be of aseptic design to avoid recontamination of product.
Sugar supplied to a plant in liquid form can go directly to on-site buffer storage, whereas granular sugar has to be dissolved in water to obtain a solution of specified Brix content. Small quantities of ingredients for the production of nectars and fruit drinks may be premixed before routed to the blending section. Sugar dissolving and ingredient mixing are usually carried out batchwise.
Filling
Effective cleaning of all process line equipment is essential for good operational results. The cleaning unit supplies the required solutions and controls the cleaning sequences. A large central unit may clean the whole plant, or there may be locally placed units for cleaning different parts of the line.
Cleaning-in-place
One pasteuriser system can feed product to one or several fillers. The same type of pasteuriser yielding commercially sterile product is used for both aseptically filled juices and nonaseptic juices intended for long shelf life under chilled conditions. A different pasteuriser design is used for hot filling.
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7.1 An overview of juice packer operations
Pasteurisation
Aseptic buffer
Pasteurisation
Aseptic buffer
Filling
Fig 7.3. Processing lines using NFC as raw material.
Automation and process control
NFC preparation
Operators control individual processing units via panels located near the equipment or from a central control room where the whole process line is supervised. The automation system may supply on-line information to management along with regular reports, and may be directly linked to the production scheduling department.
Solid frozen NFC is liquefied before processing. Rapid thawing is achieved by initial heating in a tunnel followed by tipping the drum contents into an ice-crusher. The ice slurry is then melted in a tubular heater. Juice in tanks and aseptic bags is liquid and can be pumped directly to buffer tanks. Aseptic bags are emptied via a hose pump inserted into the top of the bag, or with a pump connected to the emptying spout at the bottom of the bag. Liquid NFC goes to buffer tanks. Here juice of different origins may be blended and pulp added. Pasteurisation and other downstream processing steps are carried out in the same way as for reconstituted juice shown in Lines 1 and 2.
NFC storage
Processing lines using Not From Concentrate (NFC) as raw material are shown in Lines 3 and 4. Frozen NFC, usually in 200 l drums, is stored at –18 °C. Aseptic bulk NFC, typically in aseptic storage tanks or aseptic bag-in-box containers, is stored at 0 °C or higher.
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7.2 Raw material reception and handling
7.2 Raw material reception and handling
TABLE 7.1 QUALITY CONTROL OF INCOMING CONCENTRATE
A certain on-site stock of raw materials is required to ensure smooth production and avoid unplanned stops. Stocks are generally kept as small as possible to minimise storage space and inventory capital. However, stocks are also used to take advantage of the market situation when changes in supply prices are forecast. Raw materials arrive in several different forms. Concentrate for high-volume production arrives by road tanker. Other raw materials may arrive in frozen drums and aseptic bag-in-box containers. Specialty and add-back products come in various smaller containers, such as drums, boxes and cans. Sugar, for production of nectars and juice drinks, is delivered in granular form or as a liquid solution. Sampling and lab analysis to check that incoming raw materials meet agreed specifications is carried out regularly. Such routine checks for orange concentrate are described in Table 7.1. Authenticity checks to ensure product origin are carried out as deemed necessary. Analyses to control product authenticity are quite elaborate and require sophisticated analytical equipment (see also Section 11).
Sampling of road tankers – one representative sample per compartment taken at 10 cm minimum below the surface – one microbiological sample – temperature Sampling of drums – one representative sample per batch At >55 °Brix direct sampling At <55 °Brix sampling after thawing and mixing Testing of concentrate – Brix by refractometer – Brix corrected for acid – Total microbial count
– Acid content – Brix/acid ratio
Testing of final product (prepared in lab. according to own formula) – Brix dilution – Taste – Acid content – Appearance – Colour - Flavour – Defects – Sinking and floating pulp Source: Döhler-Eurocitrus
If this leads to microbial problems, a UV lamp can be fitted in the top of the tank to inactivate microorganisms. The concentrate tanks, which are vented, are equipped with slow and gentle agitators to avoid layering of product. For relatively short on-site storage periods, the concentrate tanks are not always equipped with nitrogen blanketing. However, measures should be taken to prevent air from being mixed into the concentrate during agitation or tank emptying. Concentrate is pumped from storage tanks to the blending system area, typically by using positive displacement pumps. Concentrate at low temperatures is very viscous and therefore the fitting of valves between the tank and pump is avoided as they cause high pressure drops. Pipe routing for product transfers made in the concentrate room is usually carried out manually using swing bend panels or flexible hoses. Automated routing systems are not common because of the large number of routing options and the desire to avoid valves in concentrate lines.
7.2.1 TANKS FOR CONCENTRATE STORAGE
Concentrate arriving in refrigerated road tankers is pumped directly to storage tanks (20–50 m3) located in a refrigerated area. The refrigerated area is preferably maintained at –5 °C to 0 °C, although this is not always the case. The maximum storage period depends on the actual refrigeration temperature. There should be no significant increase in microbial load of the concentrate while in on-site storage. Instead of using standard tanks stored under refrigeration, individual storage tanks may be equipped with double walls with a coolant flowing in the jacket. Microbial growth is slow in orange concentrate due to its high sugar content, i.e. high osmotic pressure. Basically, there is no microbial growth in concentrates of 66 °Brix at temperatures below 0 °C. However, a liquid layer of low sugar concentration may form on top of the concentrate inside the storage tank due to condensation of water vapour on the cold product.
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7.2 Raw material reception and handling
Water flushing and cleaning-in-place of the concentrate lines are carried out less frequently than in the downstream part of the plant. This is because good operating routines, and the high Brix values and low temperature of the concentrate, hinder microbial growth. Moreover, during flushing, the water/concentrate interphase and possible residual pockets of liquid at low Brix values create conditions for spoilage organisms to multiply rapidly. The water from flushing is collected in separate tanks to be used for the reconstitution of juice products.
The drum contents are then emptied into a vessel having rotating knives which chop up the frozen product into a slurry of ice. The slurry then passes through a tubular heater to melt. The liquid product is collected in a buffer tank. A quick-thawing line can process a large number of drums per hour (up to 60 drums per hour equivalent to 10,000 l/h of product). As hot air and steam are used to heat and melt the ice, it is an energy-intensive system that entails a significant investment. Juice packing plants that receive only a limited amount of frozen product in drums have often developed their own less costly solutions for thawing. Partial thawing of the drum contents at ambient temperature is followed by crushing with a smaller “chopper” before the slurry is added to the blending tank. As there is a risk of microbial growth while the juice or pulp slowly thaws at ambient temperature, this method must be carefully monitored.
7.2.2 DRUMS WITH FROZEN CONCENTRATE
Product frozen in 200 l drums (typically frozen concentrate, NFC and pulp) is placed in frozen storage at –18 °C or lower. As FCOJ at –18 °C is practically not pumpable, its temperature is raised to about –5 °C or higher at the time of use. This is achieved through several methods, such as a hot jacket around the drum, hot air circulation or simply leaving the drum in a nonrefrigerated area. The preferred method depends on the daily production volume and how much advanced notice is received from scheduling. Concentrate is either pumped out of a drum using a submersible hose pump, or emptied into an open vessel connected to a discharge pump (a quicker method). Concentrate flows either directly to the dilution tanks for blending with water or to a concentrate buffer tank for mixing with other concentrate(s). As some product remains inside the bag, it is recovered by mangling the plastic bag or rinsing it with water which is then added to the blending tanks.
Drums from frozen storage
Pre-thawing
Drum tipper
7.2.3 DRUMS CONTAINING SOLID FROZEN PRODUCTS
Ice-chopper
Raw products such as NFC, pulp and concentrates of lower Brix freeze solid at –18 °C. These are prepared for processing by placing them to thaw out in a nonrefrigerated area or by using a system for quick thawing and crushing of product in drums. Figure 7.4 shows the principal steps for rapid thawing of frozen product. The drum passes through a hot air tunnel to allow the outer layer of the product to melt.
Ice flakes
Ice-slurry melter
Liquid juice to buffer tank
Fig. 7.4 The thawing and crushing of solid frozen product from drums.
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7.2 Raw material reception and handling
7.2.4 ASEPTIC BAG-IN-BOX CONTAINERS
7.2.6 RECLAIM PRODUCT
Orange concentrate in aseptic bag-in-box containers (200 l drums) is placed in cold or frozen storage on site. Long-term storage should be at max. 5 °C to limit quality deg radation. When required for processing, concentrate is pumped from bags in a similar way to FCOJ in drums. (See subsection 7.2.2.) While aseptic bags are not often used for orange concentrate, large volumes of NFC are stored and transported in aseptic bags – typically about 1,000 l (300 gal) juice per bag. There are three methods of emptying juice from aseptic bags: • Manually with a hose pump inserted through the filling spout or through a cut at the top of the bag. • Controlled emptying by connecting a pump to an emptying spout at the bottom of the bag. In this way the product may be less exposed to air. • Aseptic withdrawal of juice through an aseptic connection to the emptying spout. If this is followed by aseptic transfer, the juice does not require repasteurisation prior to packaging.
Although reclaim, or rework, product is not a raw material supplied to the gate of the juice packing plant, it is still used as a basic ingredient in juice production. At many points in the juice packing plant, product is collected which, for some reason, is not allowed to be routed further in the process or packaging sections. This “reject product“ can be: • liquid rinsed out from concentrate containers and delivery trucks • product/water interphase from water flushing at the start of cleaning cycles • juice left in a batch blending tank at the end of a production run • juice of too low (or too high) Brix level at the start of in-line blending operation • juice rejected from the pasteuriser due to underpasteurisation • juice rejected from the pasteuriser due to overprocessing caused by (excessive) recirculation through the pasteuriser • juice filled into unacceptable containers The reclaim “juice” is too valuable to be sent to drain. It has incurred costs in the form of raw material, import duty, freight charges and processing up to the point of collection. Moreover, its discharge as effluent would not be acceptable for environmental reasons. As far as possible the reject product is used to produce the same type of juice as it was collected from. This, however, is not always possible for products demanding strict quality specifications. In this case the reclaimed juice is used in orange products not intended as premium brands, or in the manufacture of multi-fruit juices and fruit drinks. Operating procedures and equipment design in the juice packing plant should aim at minimising reclaim volumes. Rework product not only entails reprocessing costs but often ends up in a final product of lower value than that it was originally intended for.
After emptying, NFC is sent to a buffer tank prior to pasteurisation. Blending of NFC of different origins may also take place here. 7.2.5 TANKS FOR NFC
NFC may also be delivered to the juice packer by refrigerated tank car, either prepared by crushing at a blending house or transferred from aseptic storage tanks at a juice processing plant or a reception terminal. Transport in tank cars is done under hygienic but not aseptic conditions. Upon arrival at the juice packer, NFC should be kept in refrigerated tank storage at 0–4 °C for a limited time before blending, pasteurisation and filling consumer packages.
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7.3 Water treatment
7.3 Water treatment TABLE 7.2 SOME SPECIFICATIONS FOR WATER USED IN BEVERAGE PRODUCTION
Water is the largest ingredient in reconstituted orange juice and orange-based drinks, cor responding to 80–85 % of the final juice. The quality of reconstitution water significantly influences the final product. The water removed from the juice when it is concentrated is in principle distilled or “pure” water. But distilled water is not normally used for reconstitution. Water from municipal supplies or from private wells normally needs further on-site treatment to make it suitable for reconstitution of good quality juices.
Smell Taste Colour Turbidity Dry matter, mg/l Total hardness (as CaCO3), mg/l Alkalinity (as CaCO3), mg/l Chlorine, mg/l Iron, mg/l Manganese, mg/l Trihalomethane (THM)
7.3.1 WATER QUALITY
There are no regulatory standards specifying water quality for beverage production other than that it should fulfil individual national standards for drinking water or those of the WHO (the World Health Organisation run by the United Nations). Council Directive 98/83/ EC provides legislation on water quality for human consumption for the European Union. However, although water may be of acceptable drinking quality, it may be unacceptable as reconstitution water, giving rise, for example, to off-flavours in reconstituted juice. A list of some recommended specifications for water used in beverage production, also referred to as product water, is in Table 7.2. The effects of various water impurities on juice quality are discussed in subsection 4.1.1. Water hardness is an important quality parameter. It is caused by dissolved calcium and magnesium salts. Temporary hardness results from calcium and magnesium bicarbonates, permanent hardness results from chlorides and sulphates. Total hardness, the sum of temporary and permanent hardness, may be expressed in different ways. In North America it is expressed as calcium carbonate, CaCO3, in water (i.e. the concentration of different salts calculated as the corresponding quantity of CaCO3). In Europe the expression °dH, degrees German hardness, is commonly used along with °f (France). The concentration of ions in water (expressed as meq/l) is often used in East European countries.
none none none 1 unit or less <500 <100 <50 <0.05 <0.1 <0.1 none
Source: Tetra Pak
In everyday language, water hardness is simply described as soft or hard water. However, the ranges from soft to hard vary between countries. Typical ranges expressed in different units are given in Table 7.3. Water for juice production should be soft, <6 °dH.
TABLE 7.3 WATER HARDNESS
Very soft Soft Moderately hard Hard Very hard
CaCO3 mg/l
Degrees German hardness °dH
Millequivalent /litre meq/l
<50 50–100
2.8 2.8–5.6
1 1–2
100–200 200–400 >400
5.6–11 11–22 >22
2–4 4–8 >8
Conversion factors: 1 °dH = 17.9 CaCO3 mg/l 1 meq/l = 50.0 CaCO3 mg/l 1 °f = 10.0 CaCO3 mg/l 1 ° Clark = 14.3 CaCO3 mg/l 1 grain/US gal = 17.1 CaCO3 mg/l The ranges for soft and hard water may vary between different geographical regions. Source: Vattenteknik
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7.3 Water treatment
Raw water
Bag/cartridge filter
Softening
Activated carbon filter
Ultraviolet light
Buffer storage
Reverse osmosis
Fig. 7.5 A typical water treatment system used in a juice packing plant.
Product water to storage
7.3.2 WATER TREATMENT METHODS
Sand filtration
The quality of incoming water determines the types of water treatment carried out at the juice packer. To fulfil water quality recommendations, on-site water treatment should aim at: • removing organic matter • reducing hardness • removing salts • removing chlorine • removing iron and manganese compounds • destroying all microorganisms • maintaining a consistent pH value
This involves passing water through a sand filter held in a tank to remove insoluble solids. A sand filter consists of several layers of sand which vary in coarseness. It may be used as final filtering after flocculation or iron-manganese oxidation. Iron and manganese removal
Under appropriate conditions, iron compounds in water form flocs when oxidised by air. The flocs are subsequently removed in a sand filter. Manganese and iron compounds are removed by a combination of oxidation and filtration through a sand filter with a “manganese-treated” filter bed. The latter is regenerated by potassium permanganate.
Several common water treatment methods are described below. Some treatments such as ion-exchange, reverse osmosis and nanofiltration techniques may be used on a partial stream followed by blending with the rest of the water stream to achieve the desired water quality parameters. Figure 7.5 shows a combination of treatment steps for product water. However, depending on water quality and juice packer preference, several alternative combinations may be worked out.
Dealkalisation by ion-exchange
A method used to reduce the alkalinity of water. This may be required as high alkalinity neutralises the acidity of fruit juices. The presence of carbonates and hydroxides, e.g. of calcium and magnesium, in water makes it alkaline (pH >7). These are removed by an ion-exchange process. When water is passed through a resin bed (consisting of small beads of appropriate polymer) the calcium and magnesium ions attach to the resin, and water and carbon dioxide are produced. Reducing alkalinity also reduces the hardness of the water.
Flocculation
A method for removing suspended particles, such as organic matter and humic acids from water. The addition of appropriate chemicals (flocculants) to incoming water aggregates the particles to form flocs which settle on the bottom of the reaction tank. Flocculants commonly used are aluminium sulphate and iron sulphate. Flocculation is normally not needed for a municipal water supply because organic matter has already been removed in the municipal waterworks.
Softening by ion-exchange
In this method, calcium and magnesium ions are replaced by sodium ions by passing water through a bed of resin in a similar way to dealkalisation. The hardness of the softened water is virtually zero. Often only part of the water is softened so that when it is blended back with the main water stream the desired hardness is obtained.
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7.3 Water treatment
Reverse osmosis
Ultraviolet light
A membrane filtration system for removing small dissolved molecules including salts. It produces virtually pure water (>95 % of dissolved salts and >99 % of organic matter are removed). Despite higher costs, the reverse osmosis method, which also reduces bicarbonate content, is sometimes preferred to dealkalisation by ion-exchange.
Passing water under ultraviolet (UV) light is a method of destroying microorganisms in water. It is a relatively simple technique of low energy usage. UV light effectively kills all microorganisms, but ultraviolet radiation is impeded by insoluble material in water. It should therefore only be applied to clarified water.
Nanofiltration
Ozone treatment
A membrane filtration system having slightly larger pores than those used for reverse osmosis. It removes par ticles larger than 1 nanometer (0.000 001 mm). This means that hardness and colour are removed together with >90 % of dissolved salts and >99 % organic matter. Nano- and ultrafiltration are being increasingly used as alternative methods to flocculation. (Microfiltration and ultrafiltration methods incor porate membranes with cor respondingly larger pore sizes.)
A method of water sterilisation using ozone gas. Being a very strong oxidising agent, ozone may also be used to remove off-taste, colour and iron and manganese compounds. Ozone is generated on-site from air. Control of the system includes converting residual ozone gas to oxygen by heat, activated carbon or ultraviolet light. Particle filters
Safety filters used for incoming water to protect downstream equipment. They are typically bag or cartridge filters of 5–10 µm pore size.
Chlorination
Chlorine is the most widely used sterilant for water. Nevertheless, it should not be added to water containing humic organic matter because trihalomethanes (THMs) are formed. Chlorine is most efficient as a disinfectant at pH <4. As it reacts with several substances in water, sufficient chlorine must be added to ensure enough is available to destroy any microorganisms. The chlorination step must be followed by the removal of residual chlorine. Chlorination is normally not needed for municipal waters. However, residual chlorine left in the water should be removed as it will otherwise react with orange flavour and result in reconstituted juice with a flat taste.
7.3.3 IN-PLANT DISTRIBUTION OF PRODUCT WATER
From the water treatment section, product water is distributed through pipes to the point of use in the plant. Short but intensive periods of water usage may occur simultaneously at several outlet points, exceeding the output from the water treatment plant. Buffer storage of treated water is therefore recommended with a volume typically cor responding to two hours’ water production. It is advisable to recirculate water in the storage tank through a UV disinfectant unit to limit bacterial growth. The water distribution system must be capable of handling high peaks of water consumption while maintaining high water supply pressure. An increase of production capacity in the juice packing plant may make the water distribution system inadequate. In this case, a pressurised tank of a few m3 can overcome the problem of drop in supply pressure during periods of peak water consumption.
Activated carbon filter
Activated carbon is a highly porous material with a very high adsorbent capacity. Filtering water through activated carbon removes colour and odour. When there is a risk of microbial contamination of filters, UV treatment on the outlet flow is recommended as a safeguard. An alternative is to equip the filters for steam sterilisation, although this makes the filter system considerably more complex and increases the investment. Chlorine adsorbed to the active carbon is regenerated during steam sterilisation.
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7.3 Water treatment
Water feed Vacuum
7.3.4 DEAERATION OF WATER
The amount of air – or more precisely the oxygen content – in water greatly influences the oxygen content of reconstituted juice. Treated product water may contain both free and dissolved air. Free air (bubbles) may be released by holding the water in a buffer tank for a certain time, but the removal of dissolved oxygen requires a deaeration process. Dissolved oxygen levels in cold water are typically 10–12 ppm, depending on temperature and pressure. The solubility of oxygen in water is shown in subsection 4.2. Provided that the concentrate has been handled carefully (without mixing in air) and that blending with water is done in the absence of air, reconstituting with deaerated water results in a packaged juice with very low oxygen content. There are several different water deaeration systems intended for preheated water or water at ambient temperature. Figure 7.6 illustrates a deaeration system working under vacuum suitable for both preheated water and water at ambient temperature. Water passes down through a column with internal packing. The large contact area between water and vapour phase makes it easier for the dissolved oxygen to leave the water. Dissolved oxygen in the outgoing water is about 0.5 ppm. Water deaeration is common practice in breweries and carbonated soft-drink production, as it facilitates the subsequent carbonation step. It is not yet so common in juice production, where juice deaerators dominate. In juice packing plants today, the equipment used upstream of pasteurisation often allows the product to come into contact with air. Oxygen is thereby reintroduced into already deaerated product.
Fig. 7.6 The operating principle of a water deaeration system.
Deaerated water
7.4.1 BLENDING OF NECTARS AND FRUIT DRINKS
Several different concentrates can be premixed prior to the blending step or they can be added to the blending tank (in the case of batch blending). When oil fractions are added at site, they should be thoroughly mixed into the concentrate prior to the blending step. Alternatively, they can be prepared as a water-oil emulsion added at the blending step. Moreover, pulp and water-soluble flavours may be added at the blending step. As the name implies, NFC is not diluted with water, although NFC having different characteristics are often blended before pasteurisation. Essence aroma may also be added to NFC at this stage if legally permitted. If the end product is a nectar or fruit drink, other ingredients are added at the blending step. When sugar is added to orange juice it may no longer be called juice but becomes a fruit nectar. Regulations stipulate what may be added to fruit nectars. For example, EU Council Directive 2001/ 112/EC defines fruit nectars as fruit juice to which water and sugar have been added. The fruit juice can be as juice, concentrate or powder, and sugar may be substituted by honey or sweetener. Minimum juice contents are specified for each type of fruit, which for orange nectar in Europe is 50 %.
7.4 Blending In the context used here, the term “blending” means the actual reconstitution step whereby concentrate is blended with water to make a ready-to-drink juice. Blending takes place just prior to pasteurisation.
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7.4 Blending
Fruit juice regulations do not cover fruit drinks, which fall under general food legislation. In addition to what may be used for nectars, ingredients for still fruit drinks include: • artificial flavours • natural and artificial colour • stabilisers and antioxidants • preservatives
The required hourly output from the blending section is determined by the downstream filling rate and the total volume of juice to be packaged. The quantities of concentrate and water to be blended can be calculated approximately from the Brix value of the concentrate and that of the final product. A calculation example is shown in the fact box. Certain tables with density values for pure sugar solutions at different concentrations are used in the citrus industry as a common reference to determine the weight of solids in juice and concentrate. (An abstract is given in Section 13, Abbreviations weights and measures.) In practice, the density values are approximate for orange juice because it is not a pure sugar solution but contains varying amounts of insoluble solids and acid. The actual Brix value of concentrate may differ from the specification by, say, ±0.5 °Brix. Hence, in the case of orange juice, the exact Brix value of the final juice cannot be calculated from a formula, but for high accuracy it must be determined by laboratory or in-line measurements.
Stabilisers used to maintain product consistency are, for example, pectin and guar gum, and some preservatives used are benzoic acid, sorbic acid and sulphur dioxide. Examples of antioxidants are ascorbic acid and sulphur oxide. For orange drinks with low juice content, acid needs to be added. Brix level and Brix:acid ratio are typically higher for nectars and drinks compared with pure juice. Preservatives are not required when the product is pasteurised and aseptically packed. Several of the ingredients for drinks (and nectars) are added in very small quantities. They may be added directly to the blending tanks or preferably a premix of these ingredients is prepared separately. Dissolving granulated sugar to give a sugar solution of defined concentration is often done at the juice packing plant. Sugar may be dissolved batchwise or continuously. Alternatively, sugar may arrive as a liquid solution by tank car and pumped to storage tanks on site. The choice depends on the amount of sugar used and the proximity to sugar suppliers.
QUANTITY OF CONCENTRATE NEEDED TO MAKE 1 LITRE JUICE Basis: Final juice: 11.2 °Brix Concentrate: 65 °Brix, corrected Calculation: Juice of 11.2 °Brix has a specific gravity of approx. 1.045 kg/l. In other words, 1 litre juice at 20 °C weighs about 1045 grams.
7.4.2 DEFINING THE BLENDING FORMULA
The Brix value of the reconstituted juice is the key parameter for the blending operation. Appropriate regulations stipulate minimum concentrations of soluble solids for reconstituted juice. The EU demands a minimum value of 11.2 °Brix for orange juice made from concentrate, whereas the USA sets a minimum value of 11.8 °Brix. The Brix value is measured by a refractometer and cor rected for temperature, and also for acid content for concentrates. The Brix value can also be measured with a density meter.
1 litre final juice of 11.2 °Brix contains 1045 x 11.2/100 = 117 grams soluble solids. 1 kg concentrate of 65 °Brix contains 1000 x 65/100 = 650 grams soluble solids. Result: To prepare 1 litre of juice you therefore need Concentrate: 117/650 x 1000 = 180 g Water: 1045–180 = 865 g These values are approximate because juice is not a pure sugar solution.
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7.4 Blending
7.4.3 SAVINGS MADE BY ACCURATE BLENDING
7.4.4 COMPARISON OF BLENDING METHODS
There are two principal methods for reconstituting juice: • the batch method for preparing a certain quantity of juice in a tank • continuous, in-line blending
The stipulated Brix values for reconstituted juice are minimum values and so actual values must not fall below the stipulated value. To allow for variations and inaccuracies in commercial production plants, the target Brix level for juice from the blending room is set a bit higher than the official minimum value. The necessary “safety margin” depends on the accuracy of the blending operation. Blending as close as possible to the stipulated Brix value saves a significant amount of raw material. Process control equipment and blending system design may improve the blending accuracy. An estimation of the savings involved is shown in the fact box.
Tank blending, or batch blending, is the traditional method carried out manually or with the help of automation systems. In-line blending systems, which are more recent, incorporate a high degree of automation and process control. Features of batch blending
Preparation in advance: As blending of a batch typically requires 1–2 hours’ preparation, blending room personnel need to come early to complete the first batch before the start of daily production. Fixed volume production: It is difficult to prepare exactly a predetermined batch volume. This may result in insufficient juice volume for packaging or juice left over after the production run, for which an alternative use must be found in the plant. Labour-intensive: Manual or semiautomatic blending requires the frequent attendance of blending room personnel. Variation of Brix concentration: Achieving a value close to the target Brix for the blended juice usually requires several laboratory Brix measurements followed by water additions to the blending tank. In practice, however, a shortage of time and/or labour may prevent the standard routine of repeated Brix checks from being carried out. Low investment: Manual and semi-automatic tank blending systems require a comparatively low investment. Additional raw materials may be added without the need for further equipment.
EXAMPLE OF SAVINGS IN RAW MATERIAL Blending the final juice 0.1 °Brix closer to the minimum specification corresponds to the following annual savings: Basis: Line capacity: 20,000 l/h Daily production: 10 h/day Operating days: 200 days/year Annual production: 42,000 tonnes juice Final juice (min. conc.): 11.25 °Brix Cost of raw material: 1,300 USD/tonne (Orange concentrate 65 °Brix) Savings: A reduction by 0.1 °Brix, e.g. from 11.35 °Brix to 11.25 °Brix, gives a reduction in raw material consumption of 0.1 °Brix/11.35 °Brix = 0.9 %. Annual savings in concentrate will be: 42,000 x 0.1 °Brix/65 °Brix = 65 tonnes equal to a value of 84,000 USD.
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7.4 Blending
Features of in-line blending
7.4.5 BATCH BLENDING SYSTEMS
Labour-saving: No advanced preparation, automatic flow control and continuous in-line Brix measurements free personnel for other duties. Variable juice volumes: Blending is carried out to the exact juice volumes required. Consistent accuracy: Process control and in-line Brix monitoring maintain consistent measurement accuracy close to the target Brix value. Compact equipment: In-line blending requires less space as large tanks for blending product are eliminated. Moreover, less product is lost during CIP. Small volumes of blended product: No large product volumes are at risk from, for example, power failure. Less and more compact equipment, and short residence times reduce the risk of microbial contamination. No exposure to air: Closed in-line blending system avoids exposing the product to air. Less concentrate usage: Blending closer to minimum Brix levels and no excess product left in tanks after a production run result in lower concentrate consumption. High investment: Automatic systems for in-line blending require a relatively high investment, particularly when many separate ingredients have to be blended.
Each batch blending line incorporates two blending tanks. While one tank is used for preparing a new batch, juice is pumped from the other tank to the downstream pasteuriser. Both tanks are equipped with agitators for effective mixing of the ingredients. However, agitation should be carried out in such a way as to avoid entrainment of air into the juice, which may otherwise cause operational problems in downstream processing. Efficient tank cleaning-in-place is also important to prevent microbial contamination of juice for the following production run. In a manual system, the quantities of concentrate and water (plus any other ingredients) required for a batch are calculated. First, a predetermined quantity of water (majority of the calculated volume) is fed into the blending tank followed by concentrate. The volume of concentrate is often measured as a number of drums. Other ingredients, including flushing water from drum rinsing, are then added to the tank. The Brix value of reconstituted juice is checked after thorough mixing in the tank. More water is then added to get nearer the target Brix value. When the desired Brix value has been reached, the product is ready for pasteurisation. Changeover to the full tank takes place when the other tank becomes empty. Product is pumped from the full tank to the pasteuriser section. In the semi-automatic batch blending systems, recipes are preprogrammed in a process control unit. When a recipe is selected, together with relevant data for the production run in question, the control unit calculates the quantities of ingredients to be blended.
General conclusions
The choice of blending system depends on several factors, but the major conclusions are: Batch blending is best suited to small production runs and/or many ingredients as found with speciality beverages, for example. In-line blending is best suited to large volumes of products requiring few ingredients, e.g. high turnover consumer products like pure juices. A combination of the two blending principles may be applied to fruit nectars and fruit drinks containing several ingredients. The smaller quantity ingredients are pre-mixed batchwise followed by in-line blending with water and juice concentrate. The two blending principles involve different features.
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7.4 Blending
Treated water
Concentrate
The addition of water and concentrate (and perhaps syrup) is automatic and controlled through weighing the tank contents (by load cells in the tank legs) or by mass flow meters. Sampling to check Brix values is done manually. The actual Brix value is entered in the controller and the water volume needed to make the correct adjustment to the tank contents is calculated and the water then added. After thorough mixing, the Brix value is again checked manually and further adjustments made to the tank contents if necessary. In a fully automatic tank batch blending system, the Brix value of blended product is checked continuously by an in-line meter. Adjustments are then calculated and carried out through the control system. The in-line Brix sensor is placed in a circulation loop over the tank to make sure that the sample is representative of the tank contents. Figure 7.7 shows the operational principle of a batch blending system. Semi-automatic systems are widely used for batch blending, but fully automatic systems, which require significantly higher investment, are less common.
Fig. 7.7 The operating principal of a typical batch blending system.
Blended juice
In-line blending based solely on volumetric measurements achieves limited blending accuracy. This is due to variations in density and Brix of the concentrate caused, for example, by air bubbles trapped in the viscous concentrate and Brix variations of the concentrate in the tank. Thus volumetric blending, for example with piston pumps, needs to be combined with an exact Brix measurement system for the blended juice, in order to obtain high blending accuracy. Mass flow meters, which are highly accurate, measure both mass flow and actual density of the ingredient streams. The Brix value of final juice is calculated from the ratio of the two flows. For FCOJ, however, flow meters are deliberately overdimensioned to avoid excessive pressure drops on the very viscous fluid. In this case the flow meters may be less accurate as they operate outside their optimal flow range. In-line Brix measurement of blended product by refractometry is a direct measurement of the final juice. As it is the same measurement method as specified for the final product, deviations due to inaccurate conversion factors are avoided. If, however, the in-line analyser is a density meter, which gives higher accuracy, and the lab analyser is a refractometer (common in a juice plant) there is a slight difference between the measured Brix values due to citric acid and aroma content. This deviation is adjusted to zero by using a correction factor in the in-line density meter. FCOJ from cold storage is very viscous and does not mix easily with water, so effective in-line mixers are required to obtain a homogenous mix.
7.4.6 IN-LINE BLENDING SYSTEMS
The operational principle behind in-line blending is that the ingredients are continuously fed and mixed in-line on the way to pasteurisation. Critical factors for the high performance of in-line blending systems are: • high blending accuracy • effective mixing of concentrate and water • ability to adjust the flow rate through the blending unit to suit that required by downstream equipment (pasteurisers and fillers). There are three methods of measuring and controlling the flow rate of the ingredient streams, which in turn determines the blending accuracy: • by volume (piston pumps) • by weight (mass flow meters) • by Brix values in blended juice (in-line Brix meter)
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7.4 Blending N2 /CO2
Concentrate or premix
Brix meter
Mixer Brix meter
Figure 7.8 Flow diagram of a twostream in-line blending system.
Treated water
Blended juice
An example of an in-line blending system is shown in Figure 7.8. Brix control is achieved by combining an in-line Brix meter (density meter) located in the juice stream and ratio control of water to concentrate flow. The total flow rate through the blending unit varies to match filler demand, but the ratio of water to concentrate is maintained constant. Other raw goods, including reclaimed product, are added at a certain percentage of the total flow. On the way to the pasteuriser section, blended juice flows through a small buffer tank which allows operational flexibility and enables smooth adjustments to the flow rate of blended juice.
partly reflected to the liquid. Rays with a gentle angle are totally reflected to the image detector. The angle at which the total reflection starts is called the critical angle. The critical angle is determined from the borderline between the light and dark areas on the detector, which corresponds to the refractive index. The measured value, expressed as Brix value, must be cor rected for temperature. This is often done automatically by a temperature sensor in the instrument. The measurement accuracy depends on the sensitivity of the instrument. Advanced refractometers for use in a controlled laboratory environment are far more accurate than hand-held units used for quick checks in the plant. Refractometers placed in-line of a process are calibrated against laboratory refractometers. High accuracy of the latter is therefore important.
7.4.7 HOW A REFRACTOMETER WORKS
The most common way to measure Brix in juice plants is by refractometry. This is carried out by using either hand-held, laboratory or in-line refractometers. These measure the refractive index of a liquid by detecting how much of the emitted light is reflected by the liquid. (The refractive index of a liquid depends on its concentration of soluble solids. Refer to subsection 2.2.) The measuring unit of a refractometer consists of three main components – a light source, a prism and an image detector. The measuring unit illustrated in Figure 7.9 detects the critical angle of light. The light source directs light rays through the prism into the liquid. The light rays meet the liquid surface at different angles. Rays with a steep angle are partly reflected to the detector and
Optical image Light Source
Prism
Liquid
Fig. 7.9 The working principle of a refractometer.
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7.5 Pasteurisation and deaeration
7.4.8 HOW A DENSITY METER WORKS
Density (Greek letter ρ) is the quotient of the mass m and the volume V of a substance: ρ = m/V (kg/m3) As density depends on temperature, a measured density must be stated together with the surrounding temperature. Compensation to express density values at a reference temperature (usually 20 ºC) is necessary to allow comparison of measurements taken at different temperatures. There is a correlation between density and sugar concentration, or Brix. The relationship density/Brix for sugar solutions has been determined and published. One common method of measuring the density of a liquid is to feed the sample through an oscillating tube. When the liquid enters the tube, the frequency of the oscillation decreases, and the density can be calculated from the difference in oscillation between the empty and full tube. Temperature and density signals from the density meter are used in a calculation needed to express density values at the reference temperature. The accuracy of a density meter is generally higher than that of a refractometer. Although density meters are frequently used to measure Brix in carbonated soft drink production, they are not commonly used in the juice industry as yet. For orange juice, a correction factor is required when converting density measurements to Brix values to compensate for solids other than sugars in the juice. See subsection 13.3.
Cold product Hot product
Fig. 7.10 Principles of flow and heat transfer in a plate heat exchanger.
General aspects of microbiology and pasteurisation are discussed in subsections 4.3 and 4.4 respectively. It is recommended that juice intended for nonaseptic packaging, chilled distribution and long shelf life (> 20 days) is commercially sterile as it leaves the pasteurisation process. It should therefore be processed in the same equipment and under the same hygiene conditions as juice to be filled aseptically. However, the combination of temperature and residence time may be chosen closer to the theoretical minimum level, i.e. a lower safety margin to take care of raw material variations. Conversely, the misconception is sometimes found in the industry that juice for aseptic filling requires considerably more heat load than chilled (nonaseptic) juice. However, orange juice, along with other high-acid products, requires heat treatment of 80–95 °C for 15–30 sec. to be made microbiologically stable for chilled storage or storage at ambient temperature. (Ultra high temperature, UHT, is not required). The most important criterion for selecting pasteurisation conditions is the microbial load of the juice to the pasteuriser.
7.5 Pasteurisation and deaeration The pasteurisation of reconstituted juice and NFC at the juice packer is carried out to destroy any microorganisms that have entered the concentrate or NFC after the heat treatment(s) earlier in the production chain. Enzymes in the juice were inactivated by the first heat treatment at the fruit processor´s plant.
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7.5 Pasteurisation and deaeration
7.5.1 SELECTING THE HEAT EXCHANGER
Plate and tubular heat exchangers are the most commonly used equipment for heat treating juice (and other fruit drinks). Both types of heat exchanger enable good heat recovery, thus keeping down operating costs. A plate heat exchanger consists of a series of stainless steel plates clamped together in a frame (see Figure 7.10). Product to be heated flows on one side of the plate, while the heating medium usually flows in the opposite direction on the other side. The heating medium may be product being cooled down or circulating hot water. Characteristic features of plate heat exchangers are compact design, high heat transfer rates, very high degree of heat recovery and low hold-up volumes. Plates are designed with different corrugation patterns. Patterns which result in few contact points between the plates yet cause good liquid turbulence are recommended for juices with a high content of suspended solids or containing short cells. This is important for effective cleaningin-place and preventing particles from sticking to the contact points. Such a plate is shown in Figure 7.11. For products with suspended solids, reversing the direction of flow – “back-flushing” – is recommended during cleaning. Multitube-type tubular heat exchangers are based on the classic shell and tube principle. The product flows through a group of parallel tubes and the heating (or cooling) medium flows between and around the tubes in the opposite direction. Both ends of the parallel tubes are welded into circular end plates which are sealed into the outer shell, usually with rubber O-rings. The tube end plate directs incoming liquid into the tubes.
Fig. 7.11 The pattern of a widestream-type heat exchanger plate.
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Product tubes
Fig. 7.12 A multitube tubular heat exchanger.
There are no obstructions or contact points for product within the tubes. An example of a multitube heat exchanger, with a floating end design that allows for thermal expansion of the tubes, is shown in Figure 7.12. The tubes are corrugated to increase the heat transfer rate. Another type of tubular heat exchanger is the triple tube. This consists of three concentric tubes placed inside each other to form channels for the alternating flow of product and heating medium. Typically, product flows through the intermediate channel, while heating/cooling medium flows through the inner and outer channels. Tubular heat exchangers are commonly designed for indirect heat regeneration (as opposed to direct product-to-product heat regeneration) using a circulating water loop to transfer heat from hot to cold product. Characteristic features of tubular heat exchangers are their ability to handle juice with cells or other liquid foods containing particles, and their low fouling rate which allows long production runs between CIP. Compared with other types of heat exchangers, the maintenance and service requirements of tubes are reduced because they have fewer seals and other parts that need replacement. The level of heat recovery is normally lower for tubular heat exchangers compared with plate heat exchangers.
7.5 Pasteurisation and deaeration
From the balance tank juice is pumped to the heat exchanger where it is heated by outgoing juice or by a circulating water loop. An intermediate water loop, as shown in Figure 7.13, is used when there is no direct product-to-product heat recovery in the heat exchanger. Preheated juice then passes to the deaerator, if included in the pasteurisation system. Deaerated juice is heated further to pasteurisation temperature, typically 80–95 °C. The additional energy needed, i.e. that not obtained by heat recovery from outgoing product, is supplied by steam. The steam heats hot circulating water in a separate heat exchanger. The temperature of the hot water must be maintained close to the juice pasteurisation temperature to avoid overheating the product. It is not recommended to use steam directly in the juice heat exchanger as it creates product burn-on and temperaturecontrol difficulties. Juice at pasteurisation temperature flows to the holding cell. This ensures that the juice is held at the pasteurisation temperature for a defined period, typically 15–30 sec. The pasteurised juice then returns to the heat exchanger where it is cooled down by regenerative heat transfer. Juice to be packed at ambient temperature then flows directly to the filler. Juice for chilled distribution is first chilled by cooling water (or other coolant) in an additional heat exchanger section before being routed to the filler.
For the final heating of product to pasteurisation temperature, a small temperature difference between product and the heating media may be chosen for both plate and tubular heat exchangers, thereby avoiding overheating the product. The choice between plate and tubular heat exchangers depends on the properties of the product to be processed. Table 7.4 is a guideline for selecting the most suitable type of heat exchanger for a particular application. Generally, tubular heat exchangers are more versatile in application than plate heat exchangers, although they entail higher capital investment. During recent years tubular heat exchangers have become the preferred solution thanks to application flexibility and low service need. 7.5.2 THE PASTEURISATION PROCESS
Although the heat exchanger is the heart of the pasteuriser, balance tank, valves and pumps are required to build a properly operating pasteuriser system. A diagram of a pasteuriser system and the flow of juice through it is shown in Figure 7.13. Juice from the blending room enters via the balance tank. This tank makes the pasteurisation process independent of flow fluctuations in the upstream feed line and keeps the conditions in the pasteuriser stable. Circulation during start-up and presterilisation is through the balance tank.
TABLE 7.4 A GUIDE TO SELECTING THE MOST SUITABLE TYPE OF HEAT EXCHANGER PRODUCT
HEAT EXCHANGER Standard plate +++ + — +++ —
Clear juices and drinks Juices with high content of suspended solids Juices with cells Concentrates without cells Concentrates with cells Key: +++ ++ + —
Best choice Good, but higher investment than best choice Good, but with limitations (such as cell length) Not suitable
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Widestream ++ +++ + — —
Tubular ++ ++ +++ ++ +++
7.5 Pasteurisation and deaeration
Product reject
Filler or aseptic buffer
Cooling water
Holding cell
Vacuum
Juice
Circulating water
Fig. 7.13 Flow diagram of a pasteurisation process.
Steam
Condensate
The holding cell and all equipment downstream of it must be aseptic, i.e. must not cause any microbiological recontamination of the juice. Equipment and controls must therefore be designed accordingly. Prior to taking in product at the start of the production run, the pasteuriser system is presterilised. During sterilisation, water heated to 95–110 °C is circulated through the system for 20–30 minutes. Where applicable, the circulating water is cooled to below 100 °C as it returns to the balance tank. After the production run, residual juice is flushed out with water and the pasteuriser system cleaned in place. Detergent may be dosed into the balance tank and circulated through the pasteuriser, or it may be connected to a central supply of cleaning liquids (see subsection 7.9). The regular cleaning routine, once every 1–3 days, should include a wash with a caustic or similar solution. Rinsing with a mild acid solution is carried out, for example, on a weekly basis.
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7.5.3 DEAERATION
Juice from blending is normally saturated with dissolved oxygen, typically at 8–10 ppm (the exception being when deaerated water is used for reconstitution and a nitrogen blanket protects the blending operation, which result in very low oxygen level in the blended juice). If floating cells (pulp) have been added, small air bubbles may also be adsorbed to the surface of the particles. As orange juice is sensitive to oxygen, it is recommended that a deaerator is included in the pasteurisation process. The effects of oxygen on orange juice quality and different operating principles of deaerators are discussed in subsection 4.2. Deaeration of reconstituted juice is similar to deaeration of NFC. It is usually carried out by passing the product through a vacuum chamber. Free air bubbles expand under vacuum and tend to escape readily from the juice, whereas dissolved oxygen is more difficult to remove. The deaeration efficiency or reduction of dissolved oxygen depends on a combination of operating factors. These are: • applied vacuum • product temperature • surface area of juice • juice film thickness • product residence time
7.5 Pasteurisation and deaeration CIP Coolant
Vacuum
For juice preheated to 50–60 °C, which allows the juice to “flash” in the vacuum chamber, good deaeration efficiency (oxygen typically reduced to 0.5 ppm) is achieved using very short residence times. At lower deaeration temperatures and with no product flashing, the removal of oxygen is much slower. Correspondingly, a larger surface area and a longer residence time are required to reduce the dissolved oxygen to acceptable levels. Some volatile components in the juice will vaporise in the vacuum chamber, both with or without product flashing. Effective condensation of these volatiles and returning them to the juice are therefore important to avoid flavour losses. A vacuum chamber for a juice deaerator system with in-line aroma recovery is illustrated in Figure 7.14. Juice entering the vacuum chamber is sprayed in an umbrella-shaped thin film to produce a large area of thin-layer liquid. As it enters the vacuum vessel, the product flashes (i.e. some water boils off) and its temperature drops a few degrees. The pressure in the vacuum chamber, or the juice inlet temperature, is adjusted so that the inlet temperature is 2–5 °C above the boiling point of the juice at the actual pressure. This fine-tuning may be carried out manually or, preferably, as part of the control system. Vapours are condensed by an internal condenser and returned to the liquid in the vessel
Juice in
Fig. 7.14 Vacuum vessel for a juice deaerator. Deaerated juice out
without any time delay ensuring consistent product quality throughout the run. Deaerated juice is pumped out of the bottom of the vessel carefully so as to avoid entrainment of gases from the vacuum chamber (oxygen) into the liquid. 7.5.4 SYSTEM DESIGN
The pasteuriser may be assembled on-site or purchased as a pretested and preassembled frame-mounted unit, including all piping and control wiring, as shown in Figure 7.15. The latter choice is gaining preference dut to its proven machine quality, particularly for systems with a high degree of automation. It shortens installation time and start up. A combination of field-proven engineering solutions and the continuous improvement of machine features is essential for the design of high-performance aseptic pasteuriser systems. The design requirements are much stricter than those found with conventional pasteurisers. 7.5.5 PROCESS CONTROL
The control system is one of the most important features of the pasteuriser system. Orange juice pasteurisers in operation today range from manually operated units to fully automatic systems. The minimum requirements for control functions, to provide a certain degree of microbiological safety, are: • control of pasteurisation temperature in the holding cell • control of flow rate through the pasteuriser • prevention of juice flow to the filler if the pasteurisation temperature is too low
Fig. 7.15 Preassembled pasteurisation unit.
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7.5 Pasteurisation and deaeration
7.5.6 CONTROL OF PASTEURISATION UNITS
The effect of heat treatment on the destruction of microorganisms depends on the combination of temperature and time. With a longer residence time, a lower temperature level is sufficient to achieve the same microbial reduction (see subsection 4.4.4). Pasteurisation Units, PU, is a way of correlating thermal effect with different time/temperature combinations. It is commonly used for tunnel pasteurisation and in the brewing industry. One PU is defined as the thermal effect of holding the product for one minute at a defined reference temperature. In the case where the flow rate through the pasteuriser is reduced but the pasteurisation temperature is maintained, the increased residence time makes the juice subject to overpasteurisation. For pasteurisers equipped with holding cells of fixed volume but which operate at multiple capacities or process juice at constantly varying flow rates, PU control may be incorporated into the control system. In this case, the desired PU value is selected by the operator. The control system will automatically adjust the pasteurisation temperature to cor respond to the actual juice throughput (and effective holding time) to maintain the specific PU. The pasteurisation effect depends on the residence time in both the holding cell and the heat exchanger. Typically 10–30 % of the total pasteurisation effect takes place in the heat exchanger, which can be taken into account by the control system.
DEFINITION OF PASTEURISATION UNITS T–Tref
General definition: PU = t x 10 Z Key: PU = Pasteurisation Units t = Holding time, minutes T = Effective holding temperature, °C Tref = Reference temperature, °C z = Temp. coefficient of microflora heat resistance, °C Calculated example for fruit juice: For microorganisms commonly found in fruit juices z values are typically 5–7. With Tref = 80 °C and z value = 7 the PU formula is: PU=t x 10
T–80 7
= t x 1.39 (T–80)
On this basis: 1 min. hold at 80 °C = 1 PU 20 sec. hold at 90 °C = 9 PU At constant hold temp: reduction of flow to 50 % → increase of PU by factor 2 For constant PU: reduction of flow to 50 % → decrease of hold temp. by 2 °C Source: Shapton et al.
For systems supplying commercially sterile product, more advanced process control is required to minimise human error and equipment failure. Such systems incorporating microprocessors or programmable logic controllers (PLC’s) also take care of recipe handling, production sequencing, automatic valve switchover and the supply of management information. The benefits of PLC control include improved product quality and safety, high process repeatability, increased production efficiency and reduced labour costs. Frame-mounted pasteuriser units are typically equipped with a control panel with PLC’s and an operator unit for manual input of data to the pasteuriser control system. The control system can also be connected to a central control room for remote communication.
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7.6 Aseptic buffer
7.6 Aseptic buffer Pasteurised juice is ready for filling. In most cases the pasteuriser is linked directly to the filler(s), which makes the two systems interdependent. However, the two systems can be operated independently by installing an intermediate aseptic buffer downstream of the pasteuriser. The buffer tank is generally connected to the product line as a “floating” buffer. Most of the juice flows directly from the pasteuriser to the filler, and only juice which is in excess (or shortfall) for the filler demand flows into (or out of) the buffer tank. In the case where blending of several juice streams is desired, and the buffer tank is used for blending, product may enter the tank through a separate inlet and leave via a separate outlet. A constant positive pressure is maintained in the buffer tank by a blanket of sterile gas (air or nitrogen). The juice is fed to the filler by the positive pressure.
Blanketing gas
Cooling water
Barrier steam
Juice from pasteuriser
Valve cluster
Juice to filler
Fig. 7.16 Aseptic tank for juice buffer between the pasteuriser and filler(s).
An aseptic buffer tank system adds to the capital and operational investment of a filling plant. On the other hand, a well-designed aseptic buffer system saves production time, reduces production losses, provides flexibility in scheduling, reduces energy consumption, and eliminates overprocessing of heat-sensitive products. Conventional tanks (equipped with CIP) are sometimes suggested for use as buffer capacity downstream of pasteurisation. However, for aseptically filled juices, and for nonaseptic chilled juices of long shelf life, such a technical solution provides an unacceptable risk of microbiological recontamination. The savings in investment costs do not compensate for the high product value at risk.
The benefits of using an aseptic buffer between pasteuriser and filler(s) are: • Avoiding recycling product through the pasteuriser during interruptions to filling. • Avoiding product recycling through the pasteuriser in order to maintain constant feed pressure to the filler. • Smooth changes in pasteuriser throughput when one of several fillers (served by the same pasteuriser) is taken into or out of operation. • Smooth filler operation by close control of constant feed pressure to the filler. • Automatic and smooth adjustment of pasteuriser capacity for fillers of varying speed, such as bottle fillers. • Reduced product losses at changeovers (water to product and product to water).
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7.7 Hot filling
7.6.1 OPERATIONAL STEPS
For aseptic tanks “floating” on the production line, a buffer capacity equal to one hours’ production or more is recommended. Tanks for single-strength juice may have round-shaped bottoms while conical bottoms are preferred for handling high-viscosity concentrates. Tanks of heavy-duty design are needed to withstand overpressure during production and steam sterilisation, and full vacuum. A cooling jacket enables rapid cooling after sterilisation. Figure 7.16 shows an aseptic tank including the connections for product flow and service media. Prior to taking in product, the tank is presterilised with steam at a minimum 110 °C for 30 minutes. The tank is then cooled down by water circulating through the cooling jacket. During cooling, sterile gas is fed into the tank to prevent the creation of a vacuum. The piping system is sterilised together with upstream and downstream equipment. During production sterile gas fills the tank space above the product level. Positive pressure is required in the tank at all times, otherwise the system is not considered sterile. The pressure is controlled to maintain the feed pressure required by the filling machine. Juice is not pumped but flows to the filler by means of pressure differential. For deaerated juice, the use of nitrogen as blanketing gas is recommended to prevent reintroducing air into the juice. A valve cluster directs the product flow, cleaning liquids and steam to and from the tank. The valves should be of aseptic type and shielded with barrier steam to prevent reinfection. For juice with added floating cells, it is preferable that the aseptic tank is equipped with a variablespeed agitator to maintain a homogenous mix in the tank. Moreover, the agitator should be of steam-shielded aseptic design. Operation of the aseptic buffer tank system may be automatic or manual. The former is preferred as it ensures high safety levels and the correct timing of process steps.
7.7 Hot filling As the name implies, in hot filling the package is filled with hot (>84 °C) pasteurised juice. Unlike aseptic filling at ambient temperature, the package is not aseptic when filled and the hot juice is used to kill the microorganisms on the surface of the container. The necessary fill temperature and “holding time” in the package depend on the type and size of container and its degree of initial microbial contamination (see also subsection 9.6.3). Containers used in hot filling are typically glass and plastic bottles, and cans. The hot filling technique is old. Simpler processing and filling equipment may be used than for aseptic “cold filling”, but the energy consumption and heat load on the product are higher. Recent designs for hot fill systems aim to speed up cooling of the packaged product and increase heat recovery. Nevertheless, the choice of hot filling is not based on product quality but on other factors, such as package type, distribution methods and availability of equipment.
hot filling the hot juice is “With used to kill the microorganisms
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on the surface of the container
”
7.8 Aseptic transfer of NFC
Juice from blending room
Heating
Hold in holding cell
Trim cooling
Drying
Tunnel cooling
In-package hold
Packages for labelling and distribution
Filling
Fig. 7.17 Basic steps of a hot filling system.
The filled packages are held at fill temperature for a certain time period and then cooled down in the cooling tunnel by a spray of cold water. The cooling water flow is usually counter-current to increase heat efficiency and reduce thermal shock, particularly with glass bottles. After cooling, the containers pass through an air blower for drying before being sent to labelling and secondary packaging.
7.7.1 PROCESS DESCRIPTION
The basic steps in pasteurisation and filling are shown in Figure 7.17. The pasteuriser for hot filling is quite similar to that used for filling juice at ambient temperature. The heat exchanger, however, is more compact as there is only little cooling of pasteurised product. Figure 7.18 shows a flowchart for a pasteuriser with tubular heat exchangers used for hot filling. Plate heat exchangers are also commonly used for hot fill systems. Incoming juice is heated to pasteurisation temperature (typically 90–98 °C) in the heat exchanger and then held at this temperature as it passes through the holding cell. Juice then flows to the trim cooler where it is cooled down to the desired fill temperature (typically 84–95 °C) before entering the filler. The pasteuriser system usually includes a return cooler for overflow of juice and to avoid overheating juice which is recirculated during filler stops. Fillers for hot filling normally work with a pressurised filling tank, although fillers of less complex design may work at atmospheric pressure. The type of filler will determine the need for a deaerator unit within the pasteuriser. Upstream deaeration of juice prevents problems with foaming in the containers. The solubility of oxygen and other gases in juice is low at the high filling temperatures.
7.8 Aseptic transfer of NFC For NFC supplied in aseptic bags to the juice packer, there are several different ways of unloading the juice from the bags (see subsection 7.2.4.). By means of an aseptic transfer system, orange juice may be transferred from the bags to consumer packages under aseptic conditions. This eliminates the need for repasteurisation and avoids additional thermal treatment of the juice. In an aseptic transfer system, the complete piping and valve system from the emptying valve at the unloading station to the filler valve is sterilised before the production run. After connecting each new bag to the unloading station but prior to withdrawal of juice, the emptying valve and bag connections are sterilised. The nature of an aseptic transfer system does not allow inspection of the incoming raw material in the same way as for other production processes at the juice packer. Hence, high and consistent product quality is particularly important.
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7.9 Cleaning-in-place
Product reject
Cooling water
Filler
Holding cell
Opional heat recovery from tunnel cooler water
Juice
Warm water
Circulating water
Fig. 7.18 Typical process flow for a pasteuriser used for hot filling.
Steam Condensate
7.9 Cleaning-in-place For good operational results, effective cleaning of plant equipment used for juice packing is essential. Depending on the size of the plant and its automation level, cleaning-in-place (CIP) is carried out in different ways. The cleaning unit is a dedicated system, frame-mounted or assembled on site, for preparing and supplying cleaning solutions to the processing equipment according to specified cleaning programs. The programs include selection of liquid, predefined temperatures and time periods. More advanced programs also allow selection of flow rates. Cleaning solutions are returned to the cleaning unit for reuse. Conductivity meters for measuring the concentration of detergent in solution may be used to check this concentration and to differentiate between the detergent solution, rinsing water or product.
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The cleaning unit also provides hot water to presterilise the equipment prior to production start. There are three principal approaches to cleaning at the juice packing plant: • No separate cleaning unit but detergent is added, often manually, to the processing equipment to be cleaned, e.g. to the balance tank in a pasteuriser system. • Small cleaning units installed locally in the plant serving a couple of processing units each. • A large central cleaning unit that provides cleaning media for the whole or part of the plant.
7.9 Cleaning-in-place
Temperature
Choosing the correct temperature for the cleaning agent used and type of fouling is a major factor in achieving effective CIP. Time
The longer a cleaning liquid is allowed to circulate, the better the result. However, after a certain period of time, the effect of additional time is negligible. Chemical
This means choosing the right type of detergent at optimal concentration. Too weak solutions will not work properly, while too strong solutions increase cost and may be corrosive to equipment.
Fig. 7.19 Cleaning unit for cleaning-in-place of juice processing equipment and filling machines.
Mechanical
An example of a small self-contained cleaning unit is illustrated in Figure 7.19. In the design of processing equipment careful consideration must be paid to its cleanability. This is not only to allow cleaning of all surfaces, such as carefully dimensioned spray nozzles, but also to minimise the interphase volumes because they result in product losses and additional use of cleaning agents. Efficient CIP gives good hygienic results as well as minimum costs for cleaning and lost product. The use of automation in cleaning also improves efficiency. It ensures consistent results as every cleaning cycle is repeated as specified. Detergent is recovered for reuse, which also contributes to reduced costs and less environmental pollution.
Increased flow rates give higher turbulence and better mechanical removal of deposits. Insufficient flow rates are often the cause of unsatisfactory cleaning results. Caustic soda is a traditional cleaning liquid for daily use at the juice packing plant. It is commonly used as a water solution of 1–2 % concentration. This solution dissolves and removes coatings of organic matter. Caustic soda is also referred to as lye or its chemical name sodium hydroxide, NaOH. It is strongly basic.
7.9.1 CIP PROCEDURES
In determining cleaning procedures, four cleaning parameters are considered – temperature, time, chemical and mechanical. The interaction between these parameters determines the cleaning result. This is illustrated in the “cleaning circle” (see Figure 7.20.) Examples of cleaning cycles are given in Table 7.5.
Temperature
Time
Chemicals
Mechanical
Fig. 7.20 The cleaning circle.
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7.9 Cleaning-in-place
TABLE 7.5 EXAMPLES OF CLEANING CYCLES An example of cleaning cycles for different processing equipment in an orange juice packing plant: Cleaning step Temperature, °C Daily cleaning for nonheated surfaces (e.g. tanks and pipes) - Water rinse cold - NaOH circulation (1.5 %) 70 - Water rinse cold
Duration, minutes 3–5 10 5
Daily cleaning for heated surfaces (e.g. plate heat exchangers) - Water rinse cold - NaOH circulation (1.5 %) 70 - Water rinse cold
3–5 20 10
Weekly cleaning for heated surfaces (e.g. plate heat exchangers) - Water rinse cold - NaOH circulation (1.5 %) 70 - Water rinse* cold - Acid circulation (1 %) 65 - Water rinse cold
5 20 5 10 10
* Use of preheated water reduces cooling down of the equipment during the intermediate water rinse.
An acid solution (e.g. 1 % nitric acid) is required to remove calcium deposits and other mineral salts. It is used less frequently than caustic soda as the high acid juice retards build up of such deposits. In addition to these primary cleaning solutions, various kinds of complex detergents containing surfactants, emulsifiers or other useful additives are available from speciality suppliers. After use, cleaning solutions of high pH may be routed to a tank where they are neutralised with acid before being discharged. In this case, spent cleaning solutions and flushing water from the cleaning unit flow past an in-line pH meter. Liquids with a pH value exceeding a preset value are diverted to the neutralisation tank in order to prevent the effluent stream from being too alkaline before discharge.
7.9.2 PIGGING
To reduce interphases with water at product changeover or at the start of cleaning cycles, “pigging” may be car ried out in some parts of the processing plant. During pigging, an object the same size as the internal pipe diameter is forced through the piping by compressed air or flushing water. The object is often similar to a ball or large cigar but referred to as a “pig”. The pig pushes any residual product in the pipes forward to downstream processing equipment or to a collection tank. Pigging systems can be useful for recovering high-value products like concentrates and aromas but they require special engineering solutions for valves.
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7.10 Quality control of final product
7.10 Quality control of final product There are two major quality factors for the final product – the properties of the juice and its microbiological condition. Most of the properties of the final juice are not influenced by the juice packing operations but result from the raw material. The quality specifications for this are defined at purchase. For reconstituted juice, the most important quality control parameter is the concentration, or Brix level, of the juice. When pulp has been added, the concentration of floating pulp in the juice must be checked. For NFC, Brix level is checked for unintentional dilution and content of floating pulp, if added. The sampling frequency for control of Brix level varies, but should be 1–2 times per hour (packaged product). The same sampling frequency is used to check the content of floating pulp. For blending systems with in-line Brix analysis, juice samples from the blending room should be taken for laboratory analysis 1–2 times per hour. For batch blending, samples for Brix control are taken from each batch before juice is withdrawn from the tank. Sampling and full laboratory analysis of juice properties on juice produced from each batch of concentrate is recommended (see Section 2 for further discussion on juice properties). 7.10.1 MICROBIOLOGICAL CONTROL
The procedures for sampling and microbiological control of end product differ between juices aseptically packaged and juices filled into nonaseptic packages for chilled distribution. Yeast is by far the most common spoilage organism in juice. Yeast contamination is usually accompanied by extensive gas formation, especially when the oxygen supply is limited. Hence, spoilage by yeasts tends to result in blown packages. Spoilage by moulds is very rare in aseptic packages with very low oxygen content. Low oxygen pressure suppresses the development of moulds.
Some strains of acid-tolerant Lactobacillus grow faster under low oxygen pressure. They break down sugars to lactic acid without formation of gas. Spoilage caused by Lactobacillus spp usually results from insufficient cleaning and presterilisation of processing equipment. Such spoilage will normally occur at the start of a production run. The action of these bacteria usually results in a high level of defects. Sampling to detect yeast spoilage is recommended throughout a production run, while checks to detect any spoilage by Lactobacillus spp should be carried out at the start of production. Some procedures for microbiological control of the end product are given below. However, it should be kept in mind that end control of packaged product does not replace hygienic control and preventive measurements in the plant. Aseptically packaged juice
Procedure to detect spoilage by yeast: • Sampling of packs corresponding to 1–2 % of production, e.g. one tray from every pallet. • Incubate sample trays in a room separate from the ordinary storage at about 25 °C (or at the normal storage temperature if it is higher) typically for one week. • Inspect visually every day, or every two days, looking for blown packs. Procedure to detect spoilage by Lactobacillus: • Weekly sampling of 5–10 packs at the start of a production run after longer production breaks (such as a weekend). • Incubate samples at 25 °C for 7–10 days or, preferably, 30–35 °C for 4–5 days. • Inspect the juice visually and by other sensory means (smell). Also perform microbial detection tests on agar plates of different media. Nonaseptically packaged juice for chilled distribution
The sampling procedures to detect microbial contamination of juice filled into nonaseptic packages vary between juice packers. The appropriate end control depends on the shelf life of juice and distribution temperature.
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8
Add-back components – volatile flavours and floating pulp
In section 8 you will read about: • • • •
• Orange juice flavours added back to orange juice. • Origin of natural orange flavours. • Important flavour molecules. • What is meant by the folding of oils. • What an add-back system consists of.
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Useful terms used in discussing pulp. The characteristics of floating pulp. How floating pulp is measured. Components added back to juice at fruit processors, blending houses and juice packers.
8. Add-back components – volatile flavours and floating pulp SUMMARY To obtain the desired flavour characteristics in reconstituted orange juice, volatile flavour components recovered from concentrate production are added back to orange juice. This can be done at several steps of its production. Peel oil, essence oil and essence aroma are the three most important flavour fractions derived from the orange fruit. Often the raw flavour materials are standardised to provide uniform and consistent flavour composition, and to improve the stability of flavour components. Orange oils contain only small amounts of the desired flavouring compounds and are often folded. This means that the bulk of the oils’ hydrocarbon content is reduced by either distillation or solvent extraction, thereby increasing the concentration of the desired compounds. Flavour systems and pulp Flavour systems are developed to give particular juice products desired flavour
8.1 Volatile flavours
characteristics. A blend of terpeneless oils enhanced with essence aroma and top-note compounds such as acetaldehyde and ethyl butyrate is an example of a complex flavour system. Pulp is considered an important byproduct for adding to juice because many consumers think it gives juice a fresher appearance and a better mouthfeel. Cell length, which is affected by the juice extraction method used, is an important property of pulp. Add-back to juice At juice processors, peel oil may be added to juice concentrate before it is stored. In addition to blending concentrates of different origin, blending houses can add volatile flavours and pulp to produce concentrates with distinct characteristics. Juice packers can add a combination of oil- and watersoluble flavour systems and pulp to juice products to achieve variety in taste, mouthfeel and appearance.
VOLATILE FLAVOUR DEFINITIONS
A number of volatile flavour types derived from different sources can be found on the market (see fact box). Volatile flavours added to orange juice must be natural flavour components derived solely from oranges.
Natural flavouring materials are those derived from acceptable vegetable or animal material by means of physical, enzymatic or microbiological extraction processes. Nature-identical flavouring materials are chemically identical to substances found naturally in acceptable vegetable or animal material. They are made by chemical synthesis or separated by chemical methods.
natural flavouring “Only components from oranges may
Artificial flavouring materials are not natureidentical materials but are obtained by means of chemical synthesis. For example, a particular synthesised compound may have an orange-like taste but cannot be found in the orange fruit.
be added to orange juice
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8.1 Volatile flavours
Boiled-off water & flavours Juice
Essence oil
Juice concentrate Essence
Essence aroma
Peel oil
Fig. 8.1 The origin of volatile orange flavours.
8.1.1 ORIGIN OF NATURAL VOLATILE ORANGE FLAVOURS
Essence and essence oil
During the concentration process in the juice evaporator, a portion of the saturated vapour from the juice is captured. This stream, containing volatile aromas and essential oils, is sent to a still mounted on the evaporator in which the important volatiles are separated from the water by distillation under vacuum and condensation by chilling. The product essence is a concentrated mixture of aqueous and oil-soluble aroma compounds. This essence is separated into oil and aqueous phases by either decantation or centrifugation. The essence oil is clear and pale yellow. This phase contains juice oil originating in the juice plus peel oil entering juice during extraction. It contributes a floral fruity, sweet and green flavour.
Orange flavour is the most delicate and complex of the major citrus flavours. So far, more than 200 volatile compounds have been determined in orange juice, although not all of these are believed to contribute significantly to the orange flavour. Volatile flavours of oranges are found in two parts of the fruit, the peel and the juice. Liquids containing volatile flavours derived from oranges are divided into the three main fractions given below depending on their origin and characteristics (see Figure 8.1). Peel oil (cold-pressed oil)
Peel oil originates from oil sacs or glands within the peel. It is recovered from the oil-water emulsion resulting from the extraction process (see subsection 5.8). The oil is clear and dark yellow, and contains mainly water-insoluble hydrocarbons. Peel oil is responsible for much of the characteristic flavour of the final juice product. Peely, heavy and green juice notes are its main sensory attributes. The recommended maximum amount of peel oil in orange juice reconstituted from concentrate is about 0.02 %. At higher levels, the oil tends to impart a harshness and burning taste to the juice.
Essence aroma (aroma, water phase)
Essence aroma is the water phase recovered from the evaporator. It is clear and colourless and contains water-soluble compounds originating from the juice. It contributes a fruity, fresh aroma and a light citrus taste. Because the volatile compounds that make up the aroma hydrolyse and gradually lose their flavour, aroma is usually stored apart from concentrate.
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8.1 Volatile flavours
TABLE 8.1 SOME MAJOR COMPONENTS OF ORANGE PEEL OIL, ESSENCE OIL AND ESSENCE AROMA Compound
Peel oil1
Essence oil2
Water Alcohols Ethanol Methanol 1-Propanol Linalool Aldehydes Acetaldehyde Acetal Trans-2-hexanal Hexanal Octanal Decanal Neral Geranial Nonanal Citranellal Dodecanal α-Sinensal β-Sinensal
85.0 %
0.1 %
0.6 %
0.5 % 0.6 % 0.1 % 0.1 % 0.1 % 0.1 % 0.1 % 0.3 % 0.1 %
Esters Ethyl acetate Ethyl butyrate
Hydrocarbons d-Limonene Myrcene Valencene α-Pinene Sabinene Other
Essence aroma2
13.0 % 0.5 % 0.01 %
0.5 %
0.002 % 0.005 % 0.02 % 0.5 % 0.5 % 0.2 % 0.1 %
0.06 % 0.007 % Trace Trace
0.005 % 0.1 %
0.01 % 0.005 %
93.5 % 1.3 % 0.1 % 0.3 % 0.2 %
93.6 % 1.8 % 1.7 % 0.4 % 0.4 %
0.02 %
2.0 %
0.07 %
1.4 %
Source: 1) Givaudan Roure 2) Johnson and Vora
During orange juice processing some other flavour by-products are sometimes recovered:
Distilled oils
The oil yield from peel oil production can be increased by passing the underflow (water phase) from the centrifuges used for separating oil through a steam stripper. Oils recovered in this way are called distilled oils.
Deoiler oils (juice oils)
Orange juice intended for NFC products often contains an excess of peel oil. This oil can be recovered by centrifugation, by flashing the juice in a vacuum chamber or by steam distillation. The by-product oils recovered this way are called deoiler oils.
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8.1 Volatile flavours
TABLE 8.2 D-LIMONENE CONTENT IN SINGLE AND FOLDED ORANGE COLD-PRESSED OILS AND ESSENCE OILS Product
Approximate d-Limonene conc. ( % v/v)
Orange cold pressed oil 5-Fold orange oil 10-Fold orange oil 25-Fold orange oil Orange essence oil 36-Fold orange essence oil
95 90 80–85 60–65 95 1–2
Source: Braddock, 1999
Some major components of orange peel oil are given in Table 8.1. d-Limonene content of some folded oils is shown in Table 8.2.
8.1.2 MAJOR CONSTITUENTS OF FLAVOUR FRACTIONS
Two characteristics of the molecules that make up orange flavour greatly determine their behaviour and in which fraction they will be found. These are: • solubility in water or oil, which depends on the structure and the size of the molecule • boiling point, which determines how volatile the flavour is
Essence oil
Essence oil is used directly as a flavour fraction or is blended with peel oil to provide the peel oil with the lighter juice-like flavour notes it naturally lacks. Essence oil is also used as a raw material for distilling out specific top-note compounds, mainly esters and aldehydes, added to natural orange aroma. The resulting enriched aroma solutions possess desired enhanced flavour properties, and they can be tailored to the needs of specific customers. Essence oil generally contributes the most fruity juice notes when added back to orange juice. Essence oil comprises a mixture of compounds found in peel oil and essence aroma. Over 90 % is d-limonene as in peel oil, but the contribution from aldehydes, esters and alcohols is also significant. The most important compound is ethyl butyrate. In fact, the price of essence oil is set by its ethyl butyrate content. The major composition of essence oil is given in Table 8.1.
For the basic structure of different groups of volatiles see the fact box in subsection 9.4.1. Peel oil
Peel oil consists of over 90 % d-limonene, a water-insoluble hydrocarbon. d-Limonene does not contribute significantly to the flavour but can have a role as a carrier of other molecules. The aldehyde compounds in the oil are the most important compounds for its flavour even though they are present in very low concentrations. Peel oil can be folded, which means that its hydrocarbon content is reduced (see following subsection) to increase the proportion of desired flavouring substances such as aldehydes and esters. These compounds provide the lighter peel flavour notes.
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8.1 Volatile flavours
Standardisation and folding of flavour fractions are achieved by such methods as blending, distillation and extraction. This can be achieved by blending raw materials from different times of the season and/or from different orange varieties. A more sophisticated way of standardisation is to adjust the content of certain compounds to a standard level by adding single compounds separated from a fraction by distillation. Peel oil and essence oil both contain about 2–2.5 % flavour compounds (called oxygenated compounds), the remainder of the oils being mainly hydrocarbons. Increased oxidative stability and water solubility of the oils are achieved by separating the oxygenated compounds from hydrocarbons. An oil that becomes reduced in volume by removal of hydrocarbons or, to be fully cor rect, terpenes (the main group of hydrocarbons in orange oils) is said to be “folded” by the ratio of volume reduction. For example, a five-fold oil has had its volume reduced by 80 %, i.e. 100 ml of single-strength oil will give 20 ml of 5-fold oil. Folded oils have increased fragrance with lighter peel notes because the harsh “burn” taste of terpenes has been removed in the folding process. Although some top- and body-notes are lost during folding, the latest processing technology minimises this loss.
Essence aroma
Aqueous orange essence aroma, sometimes called natural orange aroma or water phase, is usually collected to contain approximately 13 % ethanol as its major organic component. The ethanol content is used as a process control monitoring technique for operating the evaporator essence recovery still. Aroma comprises a complex mixture of aldehydes, esters, ketones and alcohols. Aldehydes form the most important group of compounds with acetaldehyde in highest concentration. The aldehydes found in this fraction are highly volatile and contribute significantly to the fragrance of juice. These compounds are often referred to as the orange top-notes. The major components of orange essence aroma are listed in Table 8.1. 8.1.3 FLAVOUR STANDARDISATION AND FOLDING OF OILS
Raw flavour materials vary greatly in composition. This is due primarily to fruit variety, different extraction methods, the type of recovery equipment used, seasonal variations of orange fruit properties, and flavour storage conditions. If raw flavour materials are used directly, juice product quality will be inconsistent, which is unacceptable to both the juice packer and juice consumers. Raw flavour materials are standardised to: • provide uniform flavour composition all year around • improve the stability of flavour components • increase the water solubility of flavour components
600 kg terpenes Aldehyde content 7 kg
Folding by distillation
700 kg peel oil Aldehyde content 15 kg
Fig. 8.2 Concentration effect of 7-fold peel oil. 100 kg 7-fold peel oil Aldehyde content 8 kg
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Vapour
8.1 Volatile flavours Cooling medium out Cooling medium in
Condenser
Peel oil is distilled by heating it under vacuum to evaporate the oxygenated compounds while leaving the higher boiling point components in solution. In this way separation is achieved. However, distillation cannot fully separate the two groups of compounds and a small residue of oxygenated molecules is always found in the distillate, thus lowering the aldehyde content of the pot residue or folded oil. Distillation is widely used to produce 5- to 10-fold oils. Distillation is normally carried out under reduced pressure to lower the boiling temperatures, thereby minimising unwanted chemical changes. The principle of distillation is shown in Figure 8.3. In the solvent extraction process, flavour compounds are separated from the hydrocarbons based on their solubility and polarity. The orange oil is mixed with an aqueous solution of alcohol. When thoroughly mixed, the polar flavour compounds move from the oil into the solvent. The polar flavours are recovered from the alcohol by removing the solvent using low-temperature distillation. The principle of solvent extraction is shown in Figure 8.4. Solvent extraction almost completely separates terpenes from the desired flavour compounds and can therefore be used to produce highly folded oils in the 40- to 60-fold range.
Reflux
Condensate
Feed Heat in
Residue
Fig. 8.3 The principle of distillation.
Raw peel oil and essence oil are referred to as single-fold oil. In this form they are difficult to blend into single-strength orange juice because single-fold oils are not water-soluble. Moreover, the terpenes in single-fold oils undergo acid hydrolysis and oxidation to produce unwanted off-flavours in foods and beverages. Folding increases water-solubility and stability (including shelf-life stability) of oils as the ter pene content is reduced. Folded oils are not used as sole flavour components, but as part of a flavour package. The theoretical concentration effect of 7-fold peel oil is outlined in Figure 8.2. However, in reality, over 20 % of the aldehydes may not be recovered in the folding process due to losses into the terpenes during distillation (Braddock, 1999). When oils have been folded 20 times or more, they are called terpeneless oils, as most of the d-limonene has been removed. As they are highly concentrated, they possess good stability and better water solubility. Terpeneless oils thus find wide application as modifiers with single-folded oils, blended oils and citrus flavour fractions.
Peel oil
Terpenes Solvent
Solvent & oxygenated compounds
Solvent
8.1.4 METHODS OF SEPARATING AND CONCENTRATING FLAVOURS
Separation of flavour components can be achieved by either distillation or solvent extraction. The principle of distillation is that substances with lower boiling points will evaporate earlier and faster than substances in the mixture having higher boiling points.
Peel oil and solvent (ethanol) are added to a separator chamber.
The peel oil and solvent are thoroughly mixed. Oxygenated compounds move from the oil into the solvent.
The terpene fraction separates from the solvent now containing the oxygenated compounds.
Fig. 8.4 The principle of solvent extraction.
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8.2 Floating pulp
8.1.5 CREATION OF FLAVOUR SYSTEMS
8.2 Floating pulp
The main objective in creating a flavour system is to supply the juice packer with an easy way to optimise and diversify the taste of products. A flavour system can be designed to give a unique flavour to a juice and is often the result of joint development between the flavour company and the juice packer. Blended oils are a simple form of flavour system containing a mixture of peel oils, essence oils and certain other oil fractions. A more sophisticated flavour system can be based on terpeneless oils with addition of essence aroma and enhanced with top-note compounds such as acetaldehydes and ethyl butyrate. The basic components used to create a flavour system are shown in Figure 8.5. Flavour systems represent an easy tool for the juice packers to standardise the quality of their products and to obtain an optimised flavour for particular juice products, e.g. orange juice for chilled storage or storage at ambient temperature, or for juice intended for different European and Asian markets.
Premium pulp production has become more important because adding pulp to juice products is thought by many people to give a fresher appearance and better mouthfeel to juice. Pulp can also add value to products because many consumers are prepared to pay more for a juice containing pulp. Floating pulp consists of the larger solid particles in juice comprising mainly ruptured cell sacs and segment walls. It is separated from the juice in finishers. Pulp contains mostly carbohydrates, pectin and crude fibres. The crude fibres are built up of hemicellulose and cellulose polysaccharides and give stability to the tissue forming individual juice sacs. For many years orange pulp was a by-product of little value used for the production of pulp wash or cattle feed. This has changed in recent years. Today, more pulp is processed for sale as floating pulp for addition to juice. Section 5 describes the different ways pulp is processed. This section deals with the quality and characteristics of the commercial pulp product sold for addition to orange juice.
Folded oils
Terpeneless oils
8.2.1 USEFUL TERMS
Top-note compounds
Aroma fractions
Fig. 8.5 The basic components of a flavour system.
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In talking about orange pulp, it is of great help to know the correct meaning of terms commonly used to describe raw materials and products. Pulp, juice sacs, juice cells and fibres are all terms used to describe the same thing. Adding to the confusion is the fact that many terms have different meanings when used in fruit processing and with reference to the end product at the juice packers.
8.2 Floating pulp
AT THE FRUIT PROCESSOR
FOR TRADING
Pulp
Frozen pulp
The by-product stream at different process steps within the plant and also the product sold commercially.
Finished pulp sold in frozen form. Frozen cells
Same as frozen pulp.
Finished pulp
Aseptic pulp
The pulp stream leaving the final finisher with a very high concentration of solid particles. This is the product sold as “frozen pulp”.
Pulp sold in aseptic bag-in-box containers. Contains considerably more juice than frozen pulp. AT THE JUICE PACKERS (END PRODUCT)
“Dry” pulp
Another term used for finished pulp. The name is misleading because the “dry” pulp contains juice adsorbed to solid particles
Used by some people to mean “sinking pulp” and by others to mean “floating pulp”.
Pulpy juice
Sinking pulp (suspended pulp)
Used in Florida for the pulp stream to the pulp pasteuriser and to the aseptic bag-in-box filler. The concentration of solid particles is about 500 g/litre.
Very small solid particles (<0.5 mm) which settle from the juice with time (or spin down in a centrifuge). Sinking pulp is part of all citrus juices, even those without added floating pulp.
Pulp
Solid particles in pulp
Floating pulp
These are mainly cell walls and segment walls. The cell walls are fragmented during extraction. The length of particles varies from <0.5 mm up to 25 mm.
Larger solid particles. Most float to the top after juice is stirred. Floaters
Used mainly in Florida for floating pulp.
Bottom pulp (= sinking pulp) Fibres (= floating pulp)
Very small solid particles which flow with the juice through the finisher screens.
Sometimes used to mean large solid particles.
Washed pulp
Added cells (= floating pulp)
Solid particles which have been washed with water to remove juice. Used for cattle feed or sold in frozen form after removing most of the water.
Added pulp (= floating pulp)
Frozen or aseptic pulp added to juice. Frozen or aseptic pulp added to juice.
Pulp wash
Sacs or whole cells
Sugars and other juice solubles recovered from pulp by washing it with water. Sold as 65 °Brix concentrate in frozen form. Sometimes added to orange juice before evaporation.
Intact citrus cells which still contain juice. These liquid-filled cells cannot be obtained by normal extraction methods. A product often sold canned in syrup and added to juice drinks.
Pulp concentration
Floatability
A confusing term which means the amount of solid particles in the pulp stream. Methods to measure pulp concentration vary.
The proportion of added cells that float to the top when added to juice. Unless otherwise stated, in this text the expression “pulp” refers to the product sold commercially or the by-product stream at the fruit processor.
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8.2 Floating pulp
TABLE 8.3 FACTORS EFFECTING SELECTED QUALITY PARAMETERS FOR PULP PRODUCTION Extraction method Fruit variety Time of season Fruit size Pulp recovery process Extractor settings Operation of finishers
Cell length
Oil level
• • • •
• •
Brix/acid ratio
Defect rate
Microbial status
•
•
• •
• •
8.2.2 FLOATING PULP PROPERTIES
Oil content
The two main types of orange pulp on the market originate from squeezer-type and reamer-type extractors. The two extraction methods produce pulp with somewhat different properties and therefore affect pulp quality. Pulp from reamer-type extractors has longer cells and lower oil levels than pulp produced in standard squeezer-type extractors. Due to the increased demand for high-quality pulp, some plants have extractors adjusted to optimise pulp quality rather than to maximise juice yield.
The concentration of oil is an important quality parameter when floating pulp is added to juice. This is because the oil level in the pulp stream is often higher than in the corresponding juice stream. Hydrophobic (not mixing easily with water) oil droplets and hydrophobic cell membranes are naturally attracted to each other, particularly when present together in a hydrophilic (mixing easily with water) juice environment. An excessive oil content in the final juice gives it a harsh and burning taste. A reamer-type extractor normally gives an oil content of 0.03–0.06 % v/v, whereas pulp from a squeezer-type extractor may contain oil levels from 0.05 % v/v upwards. To minimise the oil content from squeezer-type extractors, so-called low-oil extractors can be used.
Pulp properties
The properties of floating pulp are not very well defined in the juice industry or by juice packers. However, some properties are more important than others. These are discussed below. See also Table 8.3. Cell length
Generally, pulp with longer and less damaged cells has better floatability and provides a mouthfeel closer to fresh juice. A reamer-type extractor produces a pulp with longer fibres and less fragmented cells compared with pulp from a standard squeezer-type extractor. Pulp from reamer-type extractors can contain fibres up to 25 mm long. In pulp from a standard squeezer-type extractor, most cells are shorter than 5 mm and about 40 % are shorter than 1 mm. However, a new system of squeeze extraction that yields longer cells has been introduced. The visual difference between pulp from the two types of extractor is illustrated in Figure 8.6.
Standard squeezer-type extractor
Reamer-type extractor
Fig. 8.6 Illustration of relative pulp sizes after extraction.
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8.2 Floating pulp
In calculating the total oil content in the final product, the contribution from both the floating pulp and the juice must be taken into account.
Mesh number Hole size, m 20 40
850 425
Other properties
Apart from cell length and oil levels, quality parameters such as taste, colour, °Brix, ratio and microbial status are also important. The °Brix and ratio values strongly depend on what orange variety the floating pulp comes from, but they should be similar as for orange juice. Flavour and colour are often specified as “typical”.
A special method called Quick Fibre (QF) is used to analyse commercial pulp (finished pulp) leaving the producer. It determines the dryness of finished pulp and this method also uses a FMC shaker and a screen. The dryness of the pulp is set in the finishers and is an important process parameter because it determines not only the juice yield but also the quality of both juice and pulp.
8.2.3 FLOATING PULP CONCENTRATION
It is important to know the floating pulp concentration both at the juice processor and at the packer. There are several different methods of analysing the pulp concentration depending on whether it is a pulpy juice stream, finished pulp or final single-strength juice. The pulp stream or final juice can be analysed by pouring it onto a screen with defined hole size. Excess juice is drained from the screen, with or without shaking, and the screen plus pulp is weighed. The result is expressed as grams pulp per litre (or quart) juice. Alternatively, juice is poured into a glass beaker to see how much settles and how much floats after a certain time. A method used by many processors in Florida and Brazil uses screens and a certain shaker that shakes the screens at a defined frequency and amplitude. This is an attempt to standardise the screening method. Screens with different mesh numbers are used to analyse floating pulp content in the laboratories of juice plants. In Florida the 20 mesh screen is the norm, whereas some Brazilian producers use a 40 mesh screen. The hole size of screens can have a significant effect on analysis results. When smaller screen holes are used, the pulp releases more water during analysis. Therefore, exactly the same method must be used if measurements are to be compared.
QUICK FIBRE (QF) Quick Fibre is an analysis method used to determine the “dryness” of finished pulp. 200 g of pulp is mixed with 200 ml of water and stirred for 1 min, left alone for 3 min and then stirred again for 1 min. Thereafter, the mixture is screened and shaken for 3 min. A QF value equals the weight of the liquid (g) drained from the screen. A high Quick Fibre value means that the pulp analysed has a high juice content. A low QF indicates that the finished pulp analysed is dry and has absorbed some of the added water. The QF method is mainly used during fruit processing to determine the correct finisher settings. Typical classifications of QF values are listed below. Classification of Quick Fibre (QF) Finisher settings
Very tight Tight Moderate Loose Very loose
Brazil (40 mesh screen) QF value
Florida (20 mesh screen) QF value
<130 130-150 150-180 180-210 >210
<150 150-180 180-200
Source: 1) E. A. Nonino 2) Dan A. Kimball
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8.3 Components added back to juice
FRUIT PROCES SORS
Add-back: • Peel oil
BLENDING HOUSES
Add-back: • Peel oil • Essence oil • Essence aroma • Floating pulp
JUICE PACKERS
Add-back: • Flavour systems • Floating pulp
Fig. 8.7 Volatile flavours and floating pulp.
8.3 Components added back to juice
Blending houses
Blending houses supply juice packers with concentrates of consistent quality. Along with blending concentrates of different origin, flavour addition is important to achieving product uniformity. By altering the amounts and types of volatile flavours added, blending houses can produce orange concentrates with different characteristics. Floating pulp is added to improve the mouthfeel of juices and to give a fresher appearance. The pulp can be added directly to the concentrate by the blending house.
The overall juice quality is already determined at the fruit processor by the choice of raw material (quality and variety of oranges) and extraction methods. Further processing cannot increase juice quality. On the contrary, during some processing steps, e.g. evaporation, the juice loses most of its original freshness and aroma. To provide the desired flavour characteristics in reconstituted juice, volatile flavour and floating pulp can be added back at different steps of orange juice processing and packaging (see Figure 8.7).
Juice packers
The juice packer can modify the taste of orange juice by adding selected volatile flavours before finished product packaging. Oils are difficult to mix homogeneously with single-strength orange juice, and therefore need to be added to the juice concentrate before reconstitution. This is usually achieved with a batch premix system. It is possible to disperse a maximum of 2 % oil into FCOJ at a minimum 42 °Brix. This should preferably be done under a nitrogen blanket. The premix can be kept overnight under refrigerated conditions ready for production the next day. Before reconstitution, the premix blending time into the concentrate should be not less than 30 minutes to assure an even distribution of flavours in the final product.
Fruit processors
At the fruit processor, peel oil is often added to concentrate before frozen bulk storage in tanks. It is believed that the oil-soluble volatile components help to mask any processing off-flavours present in orange juice reconstituted from concentrate. A typical concentration of added peel oil in juice concentrate before storage is 0.008 % v/v. This low level still allows addition of a flavour package to the juice for reconstitution at single-strength concentration at which it is consumed.
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8.3 Components added back to juice
In general, the addition of water-soluble aromas can be carried out at any time during the reconstitution process. Normally they are added either together with the oils in the premix or later at the reconstitution step. Since the water-soluble aromas contain the most volatile flavour components, they should be added as late as possible in the process. A flavour system based on terpeneless oils provides the juice packer with a tool to simply optimise the juice taste with one single addition of flavours. Since terpeneless oils are much more water-soluble they can be added to singlestrength juice. In this context it should be noted that the addition of flavours is not the single answer to good juice taste. A sophisticated and well-balanced flavour system can enhance the flavour of a juice but can never fully mask the off-flavours from a badly produced concentrate.
When pulp is added back to the juice at the juice packer, it has first to be crushed or thawed before being added back to the blending tank. Pulp packed in 20 kg boxes can be left at ambient temperature for a few days to thaw, or the blocks of pulp can be sliced into smaller pieces and thawed in water. Nevertheless, both methods are very labour-intensive. If pulp in 200 l drums is used, crushers similar to the ones used to thaw frozen NFC are needed since the time needed to thaw a drum is long enough to result in microbial problems. The labour-intensive part of pulp thawing can be avoided by using aseptic pulp. However, there are only a small number of aseptic pulp suppliers on the market. The pulp is added to the concentrate in the reconstitution tank before it is diluted. Constant low-speed agitation of the tank is necessary to obtain even distribution of cells. Moreover, it is very important to prevent too much air from entering the juice during tank agitatation (see subsection 4.2).
147
8.3 Components added back to juice
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9
Packaging and storage of orange juice
In section 9 you will read about: • The impact of light on juice quality. • Orange juice aroma and the effect of different package types on aroma retention. • Different types of packaging systems.
• The quality parameters that need protection during storage and what affects them. • The role of oxygen in vitamin C degradation, juice browning and flavour changes.
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9. Packaging and storage of orange juice Summary One of the primary aims of a packaging system is to protect the product from microbial spoilage and chemical deterioration during its distribution and storage. For orange juice, measures should be taken to protect vitamin C and flavour compounds, and to prevent microbial growth and colour changes. Vitamin C is the compound in orange juice that reacts most readily with oxygen, and its loss correlates with the oxygenbarrier properties of the package. The degradation products of vitamin C contribute to browning. Light, in the presence of free oxygen, is known to accelerate aerobic degradation of vitamin C. Anaerobic degradation of vitamin C also takes place but independent of oxygen. The culprits of quality loss High storage temperatures combined with oxygen are the main factors involved with quality deterioration over time.
Raw materials Quality Treatment
Processing Heat treatment Oxygen
The results are loss of nutritional value concerning vitamin C, unpleasant colour changes, and off-flavour formation, which is caused predominantly by chemical changes in the juice matrix, and to a lesser degree by changes in the volatile flavour fraction. Almost all changes can occur under anaerobic storage conditions and are greatly accelerated by oxygen (headspace and dissolved oxygen, and oxygen permeating through the package). In general, packaging for orange juice should contain an aroma barrier to prevent aromas permeating out through the the package. Laminated cartons rule Laminated carton packages are the predominant form of packaging in most countries for chilled and shelf-stable orange juice. They are both made from prefabricated blanks and fed from rolls. Worldwide, glass bottles are the second most common type of container, closely followed by plastic bottles.
Bulk storage Temperature Time
Fig. 9.1 Factors which influence juice quality.
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Packaging Barriers Hygiene
Shelf storage Temperature Time
9.1 The role of packaging
9.1 The role of packaging
This means taking measures to: • protect the relevant flavour compounds • protect the high vitamin C content • prevent colour changes • prevent microbial growth
One of the main aims of a packaging system and packages is to protect orange juice from microbial spoilage and chemical deterioration during distribution and storage. The shelf life of food and beverages is the time period up to the point when the product becomes unacceptable from a safety, sensorial or nutritional perspective. The influence of packaging material and package type on the shelf life of orange juice has been the subject of many investigations. Although the package is important in protecting its contents, it cannot improve the quality of orange juice made from poor raw materials or disguise quality degradation originating from nonoptimal processing. Moreover, it is inevitable that product deterioration related to productspecific characteristics and storage conditions gradually takes place over time. Therefore, regardless of the package, the degradation of vitamin C and the browning of orange juice always take place in stored orange juice when a certain temperature and/or storage time is exceeded. In conclusion, the quality of orange juice at consumption depends on all the processing and packaging steps from raw material intake up to the product being consumed. Some important operating parameters which influence juice quality at different steps are presented in Figure 9.1.
9.1.2 FACTORS AFFECTING QUALITY PARAMETERS DURING STORAGE
No packaging system is able to completely inhibit changes in quality taking place in orange juice – or other beverages in general – during storage. From the day of processing to the day of consumption, the product will change to a greater or lesser extent depending on the storage conditions. And in most cases, except perhaps for wines, the changes will be for the worse. With regard to the quality parameters already identified for orange juice, the packaging and storage conditions given in Table 9.1 influence how long acceptable quality can be retained during storage. Before looking closer at barrier properties, it is important to keep in mind that packaging can never be discussed without considering the intended storage conditions – particularly temperature and time – because these mainly determine the barrier demands.
TABLE 9.1 FACTORS INFLUENCING SHELF LIFE
9.1.1 PRODUCT QUALITY PARAMETERS TO BE PROTECTED DURING STORAGE
In addition to its most obvious function of containing the product, a consumer package must protect the specific quality parameters of orange juice. To better understand the term “quality parameters”, one could question why consumers buy orange juice. The main answers will most probably be its enjoyable taste and high nutritional value due to a high vitamin C content. Therefore these quality parameters should be protected during a given shelf life.
Package properties Barrier against: - Oxygen - Light - Flavour losses - Microorganisms
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Storage conditions - Time - Temperature - Aseptic - Nonaseptic
9.2 Barrier properties against oxygen
For packages with good oxygen-barrier properties, e.g. glass bottles, anaerobic degradation plays the major role regarding the total loss of vitamin C. In cases where permeation of oxygen into the package is considerable, headspace oxygen is present or oxygen is dissolved in the product, the contribution of anaerobic deg radation to the total vitamin C loss is small compared with aerobic degradation. Since both anaerobic and aerobic pathways for vitamin C degradation occur simultaneously in most packaged products, vitamin C deg radation curves cannot usually be attributed to solely one pathway.
9.2 Barrier properties against oxygen Oxygen plays a major role in the loss of quality in orange juice during storage, mainly because of: • vitamin C degradation • colour changes (browning) Several publications also indicate the involvement of oxygen on flavour compounds and on off-flavour for mation during the storage of orange juice at ambient temperature. This is not yet fully understood. 9.2.1 VITAMIN C DEGRADATION
Vitamin C is the most sensitive compound in orange juice that reacts with oxygen, and its loss is consequently closely related to the availability of oxygen in packages. Generally, vitamin C is lost through two different chemical pathways – anaerobic and aerobic degradation. As its name implies, the anaerobic pathway is independent of oxygen and is mainly driven by the storage temperature. Losses caused by this degradation pathway cannot be prevented by packaging, and they are the same in all types of package. The only possible countermeasure is to reduce the storage temperature. The aerobic pathway needs oxygen and is therefore strictly related to the presence of headspace oxygen, the dissolved oxygen in juice, and the oxygen-barrier properties of the package. Both anaerobic and aerobic degradation take place simultaneously in orange juice. Which one predominates depends on the storage temperature and the availability of oxygen.
EXAMPLES OF VITAMIN C LOSS FOR A 1 LITRE PACKAGE DURING AMBIENT STORAGE BASED ON STOICHIOMETRIC CALCULATION Headspace A headspace volume of 5 ml air, containing 1 ml oxygen (about 21 %), can theoretically oxidise approximately 15 mg vitamin C. Dissolved oxygen 1 mg oxygen corresponds to a loss of approximately 11 mg vitamin C. Anaerobic degradation corresponds to an approximate loss of: 1 mg/l vitamin C per month at 10 °C 5 mg/l vitamin C per month at 20 °C 20 mg/l vitamin C per month at 30 °C Oxygen permeating through the package An oxygen permeability of 0.02 ml oxygen/ package/day in a 1 litre package results in a loss of 9 mg/l vitamin C per month during ambient storage. For a package with a permeability of 0.05 ml oxygen/package/day the loss is 22 mg/l vitamin C per month.
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9.2 Barrier properties against oxygen
500
It is quite obvious that when a certain oxygen permeability of the package is exceeded, the aerobic pathway predominates. The anaerobic reaction pathway is mainly temperaturedriven. The impact of temperature can be seen from the example of a 1 litre package in the fact box. Storage temperature is also important for aerobic degradation of vitamin C. Figure 9.3 shows 20 25 the change in vitamin C content in orange juice during storage for 30 weeks at 4 °C and 23 °C respectively in the same package type (Tetra Brik Aseptic, TBA). The calculated vitamin C loss due to anaerobic degradation is indicated in the graph. The difference in vitamin C retention between storage at 4 °C and 23 °C is obvious. During 30 weeks storage, an increase in temperature from 4 °C to 23 °C results in increased losses of vitamin C of 28 mg/l due to anaerobic degradation, and 42 mg/l due to aerobic degradation. The rate of oxidative degradation of vitamin C is slowed down dramatically under chilled storage. Consequently, packages for chilled distribution do not need as high oxygen-barrier properties as are required for packages stored at ambient temperature.
450 Vitamin C content mg/l
400 350 300 250 200 150
Good O2 barrier, anaerobic storage Good O2 barrier, aerobic storage Less good O2 barrier, aerobic storage
100 50 0 0
5
10
15 Weeks
Fig. 9.2 Vitamin C degradation curves for different packages of orange juice stored at 23 °C. Source: Tetra Pak
Figure 9.2 shows vitamin C degradation in orange juice stored at ambient temperature in two types of package. These were laminated cartons with a barrier layer of alu-foil and polymer, such as ethylene vinyl alcohol (EVOH), respectively. The alu-foil layer is a good oxygen barrier, whereas packages with a polymer barrier layer like EVOH allow higher oxygen permeability. Some packages were stored in an oxygen-free atmosphere, and in this case the vitamin C loss represents mainly the anaerobic degradation pathway.
340
Vitamin C content mg/l
320 300 280 260 240 Anaerobic degradation, 4 °C Anaerobic degradation, 23 °C
220
TBA – 250 cc, 4 °C TBA – 250 cc, 23 °C
200 0
5
10
15
20
Weeks
Fig. 9.3 Effect of temperature on vitamin C content in orange juice during storage. Source: Tetra Pak
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25
30
9.2 Barrier properties against oxygen
25 37 °C 25 °C 17 °C 12 °C
15
10 5
0 0
5
10
15
20
25
Weeks
Fig. 9.4 The browning of orange concentrate during storage at different temperatures. Source: Values taken from Kanner et al.
9.2.2 COLOUR CHANGES
The colour of orange juice is primarily determined by its carotenoid content. However, carotenoids are relatively stable in orange juice since they are protected by vitamin C and are not regarded as being responsible for the colour changes, which are most evident during long-term storage at ambient temperature. The colour changes, or rather the darkening of orange juice, during storage are based on the appearance of brown-coloured compounds caused by the chemical reaction of orange juice components present in the juice matrix. The brown compounds are formed in the end phase of the “Maillard Reaction” (also known as nonenzymatic 10 browning), which is a well-known 9 reaction between sugars and amino 8 acids. This reaction type is gener7 ally not dependant on oxygen, but is clearly temperature-driven. 6 Figure 9.4 shows the effect of 5 temperature on the browning of or4 ange concentrate. It is evident that 3 browning results mainly from the 2 long-term storage at temperatures higher than 12 °C. 1
9.2.3 THE IMPACT OF OXYGEN ON STORAGEDEPENDENT FLAVOUR CHANGES
Orange juice flavour is a very delicate mixture of different fractions which contain a variety of volatile chemicals of different chemical classes (see subsection 9.4 for more details). These flavour fractions are known to undergo several changes during storage that gradually lead to a loss of freshness and unpleasant odours, and tastes not associated with the orange fruit. Most of these changes are acid-catalysed reactions.
Package with low oxygen barrier TBA Glass
delta – L*
delta - L
20
Vitamin C can participate in the development of browning via its degradation products resulting from both the aerobic and anaerobic pathways. Consequently, the oxygen barrier of packages influences browning because it determines the supply of oxygen to the aerobic pathway of vitamin C degradation. Figure 9.5 shows colour changes in orange juice in packages with different oxygen-barrier properties dur30 ing storage at 23 °C. There is a clear increase in browning with increased oxygen permeation through the package. This leads one to conclude that the better the oxygen barrier, the lower the risk of browning. Methods of measuring colour in orange juice are described in subsection 2.2.4.
0 0
4
8
12
Weeks
Fig. 9.5 Colour changes in orange juice in packages with different oxygen-barrier properties during storage at 23 °C. Source: Tetra Pak
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9.2 Barrier properties against oxygen
Source
Type of reaction
Consequences
Degradation of important top-notes (e.g. aldehydes)
Loss of top-notes, loss of freshness
Chemical reaction to detrimental flavour compounds from terpenes, e.g. limonene
E.g. α-terpineol (carvone, carveol)
Maillard reaction
Furans, pyrones
Vitamin C degradation products + amino acids
Methional, off-flavour
Degradation of ferulic acid
Off-flavor, vinylguaiacol, guaiacol
Volatile flavour fraction
Juice matrix: sugar, amino acids, vitamin C, ferulic acid
Fig. 9.6 Storage-dependent flavour changes in orange juice.
They are supported by the high acidity of the aqueous juice matrix as well as high storage temperatures, and thus occur independently of the packaging type. Degradation pathways of important flavour constituents like aldehydes are not always known in detail but some of the reactions are, chemically speaking, oxidation reactions. This raises the question to what extent oxygen-barrier properties influence changes in the volatile flavour fraction. Limonene degradation to α-terpineol has been shown to be independent of oxygen permeating into a package. Currently no available data prove that chemical changes in the volatile flavour fraction of orange juice correlate with the oxygen-barrier properties of packages as long as reasonably good oxygen barriers are used. This is not surprising when one realises that vitamin C is a strong antioxidant in orange juice which immediately binds incoming oxygen. Three compounds have been identified as important contributors of malodorous properties in orange juice. These compounds, which gradually develop in juice, are:
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• 4-vinyl guaiacol (PVG) • 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) • α-terpineol When these compounds are added to freshly prepared orange juice, PVG imparts an old fruit or rotten fruit aroma; DMHF imparts a pineapple-like aroma typically found in old orange juice and α-terpineol is described as stale, musty or piny. Two out of the three flavours mentioned above, PVG and DMHF, derive from changes in the juice matrix and only α-terpineol is a degradation product of volatile flavour compounds. This stresses the importance of juice matrix changes in offodour formation. The acid-catalysed reactions between sugars, and reactions of vitamin C degradation products with or without amino acids, are possible sources of changes in the matrix. Since vitamin C degradation depends very much on the availability of oxygen, oxygen-barrier properties of packages should therefore have a considerable effect on off-odour formation in the matrix of orange juice during storage. Storage-dependent flavour changes in orange juice are described in Figure 9.6.
9.3 Barrier properties against light
As a consequence, light protection should be considered for use in packages for chilled distribution which have low oxygen-barrier properties.
9.3 Barrier properties against light The impact of light on the quality of orange juice during storage has been proven in respect to its impact on the aerobic pathway of vitamin C degradation (and only this pathway). Light is known to accelerate the aerobic degradation of vitamin C. One can therefore draw the following conclusions: • Light has an effect only when oxygen is present, consequently packages with high oxygen-barrier properties, e.g. glass bottles and high-barrier PET bottles, do not need a light barrier.
9.4 Barrier properties against aromas In most cases, orange juice packaging is required to provide a barrier which prevents aroma compounds permeating out through the package. Another requirement of packaging is to provide a barrier against odours from the surrounding atmosphere permeating into the packaged orange juice. This subsection discusses the composition of the aroma fraction in orange juice and the properties of different polymers and different packages commonly used.
• During storage at ambient temperature in packages with a good oxygen barrier, low permeation rates of oxygen limit the rate of vitamin C degradation and, moreover, all oxygen entering through the package is almost immediately consumed. Consequently light cannot accelerate the reaction and should therefore have no significant impact.
9.4.1 COMPOSITION OF ORANGE JUICE AROMA
Orange juice aroma, as a term generally used in this section on packaging, includes all the volatile compounds of orange juice flavour. Hence it is not identical to “essence aroma” (or water-phase aroma), which is the water-soluble volatile fraction recovered in the essence recovery unit during evaporation. See also section 2.2. Orange juice aroma is a complex mixture of many volatile compounds. In chemical terms, it is mainly a mixture of hydrocarbons, aldehydes, alcohols and esters (see fact box). The predominant fraction consists of hydrocarbons, of which one single compound, d-limonene, accounts for more
• During chilled storage, where packages with higher oxygen permeability are mainly used and where the reaction between vitamin C and oxygen is significantly slowed down, oxygen will accumulate in the product. Light can then accelerate vitamin C degradation.
TABLE 9.2 THE CONTRIBUTION OF VOLATILES TO ORANGE JUICE AROMA Contribution to typical aromas Important ethyl butyrate neral geranial
Desirable linalool limonene α-pinene valencene acetaldehyde octanal nonanal α-sinensal ß-sinensal
Contribution to off-aromas Precursors linalool limonene valencene
Source: Dürr et al.
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Detrimental α-terpineol carvone t-carveol nootkatone hexanal t-2-hexenal hexanol 4-vinyl guaiacol 2,5-dimethyl4-hydroxy3-(2H) furanone
9.4 Barrier properties against aromas
Besides specific knowledge about the composition of aromas, it is also essential to identify those individual aroma compounds that contribute most to taste and smell of the product. Dürr et al. (1981) ranked juice aroma compounds into four groups (listed in Table 9.2): • important • desirable • off-odour precursors • detrimental
THE BASIC STRUCTURE OF AROMA COMPOUNDS Hydrocarbons A group of compounds that contain only hydrogen and carbon in their molecular structure. Example: d-limonene Alcohols, aldehydes and esters contain only hydrogen, oxygen and carbon in their molecular structure. Alcohols Typical functional group: R-OH Example: linalool
Off-odour precursors mean that these compounds can undergo chemical changes during storage that lead to undesirable off-odours, even if the original compounds themselves may contribute positively to orange aroma. Examples of such off-odour precursors are limonene, linalool and valencene.
Aldehydes Typical functional group: R-CHO Example: hexanal Esters Typical functional group: R-COOR Example: ethyl butyrate
9.4.2 PROPERTIES OF DIFFERENT POLYMERS
Aromas can be absorbed into or permeate through the packaging material depending on the type of aroma compound (chemical class, polarity) and the nature of the packaging material. This effect, often called “flavour scalping”, has been extensively studied, especially for laminated carton packages. The absorption and/or permeation of aroma compounds through polymers is based on the general equation that permeation (P) is a product of diffusion (D) and solubility (S), P = D×S. Consequently, only those aroma compounds with high diffusion and solubility coefficients in respective polymers are likely to be lost through permeation or absorption during storage. The solubility of a compound in a polymer can be estimated simply by making use of the fact that “like dissolves like”.
R = a particular molecular side chain
than 90 % of the total aroma fraction. The aroma oil content of orange juice is usually evaluated by a standard test method (Scott titration), which more or less reflects the d-limonene content only. Therefore, limonene loss during packaging and storage is often incorrectly equated to flavour loss.
concentration of an “The aroma compound cannot be correlated directly with its importance for flavour
”
It is not possible to directly correlate the relative concentration of an aroma compound with its importance for flavour. For example, a compound that is 90 % w/w of the aroma fraction may contribute very little to the flavour, whereas a compound that has only a 0.001 % w/w share of the aroma fraction may have a very high impact on the flavour sensation. The reason is that the human nose and taste buds can respond very differently to compounds of different chemical structure.
PERMEATION THROUGH POLYMERS P=D×S Permeation rate = Diffusion × Solubility
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9.4 Barrier properties against aromas
Type 1
Type 2
Orange juice
Type 3
Orange juice
Orange juice
% Limonene
% Limonene
% Limonene
Fig. 9.7 The three general types of package.
Time
Time
Time
Fig. 9.8 The loss of limonene during storage in the three package types.
In nonpolar polymers, such as polyolefins, nonpolar aroma compounds like limonene have high solubility. Examples of polyolefins are low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polypropylene (PP). While there is a minor difference in solubility for nonpolar aroma compounds in the stated polyolefins, their diffusion and consequent permeation rates differ by orders of magnitude in the different polyolefins – in decreasing order LDPE>HDPE>PP. Aroma losses into the polymer layer are therefore significantly slower in PP and HDPE than in LDPE. Unlike nonpolar components, polar components such as ethyl butyrate have low solubility in polyolefins. Consequently, their permeation rates are very low and losses due to permeation are rather negligible in barrier packages with LDPE as product-contact layer. Polar polymers like polyester (PET), EVOH and polyamide (PA) essentially show very low
diffusion coefficients with polar and nonpolar aroma compounds. This results in good barrier properties against both types of compound. However, polar polymers are sometimes more difficult to heat-seal than polyolefins. In short, aroma losses due to absorption into or permeation through polymer packaging primarily involve nonpolar aroma compounds (e.g. hydrocarbons like limonene) in contact with nonpolar polymers (LDPE, HDPE, PP) commonly used as sealing layers. There is little absorption of aroma compounds into polar polymers (PET, PA, EVOH). 9.4.3 PROPERTIES OF DIFFERENT PACKAGES
The extent of loss of aroma compounds due to absorption or permeation can vary a great deal between different package types. Generally three types of package can be discussed as shown in Figure 9.7: • Type 1 package has no efficient aroma barrier, such as carton packages without a barrier layer and HDPE bottles. • Type 2 package has an aroma barrier not in contact with product, and a sealing layer like LDPE in contact with product. Most laminated cartons are type 2 packages. • Type 3 package has an aroma barrier in direct contact with product, such as glass and PET bottles.
FLAVOUR SCALPING The term flavour scalping is widely used in publications to mean the almost exclusive absorption of limonene into the internal polyethylene coatings of laminated carton packages. As limonene contributes little to orange juice flavour, the loss of limonene does not correlate with the loss of flavour in a product.
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9.4 Barrier properties against aromas
ratio of internal surface area to product volume of the packages. The larger the package size and the lower the internal coating thickness, the higher the limonene retention. Saturation will be reached after 2–4 weeks at ambient temperature. Type 2 packages are extensively used for orange juice distributed at ambient temperature or under chilled conditions.
Because absorption and permeation mainly involve nonpolar aroma compounds, limonene is a key compound in monitoring flavour scalping. For the three package types, the loss of limonene can be demonstrated using the graphs shown in Figure 9.8. Type 1
The limonene content decreases continuously by permeation through the package due to the absence of an aroma barrier. The loss over time is mainly determined by the choice of polyolefin polymers, and the slope of the curves is determined by the diffusion of limonene into the individual polymers. Consequently, for a given shelf life, e.g. 9 weeks, the limonene loss in PP would be lower than in LDPE. Type 1 packages cannot be used for long-term storage of orange juice at ambient temperature because of the extensive loss of aroma compounds. Moreover, the absence of an aroma barrier also implies the lack of an oxygen barrier. (Oxygen barriers are generally also good aroma barriers.) It is possible to use Type 1 packages for orange juice stored chilled for a few weeks, as is done in the US market with HDPE bottles. The low diffusion coefficient of HDPE limits aroma loss within the short shelf-life time period. When significant loss of quality needs to be prevented, laminated carton packages based on LDPE as sealing polymer need an aroma and oxygen barrier, even under cold storage conditions.
Type 3
In this package, the aroma barrier is in direct contact with product and practically no absorption/ permeation of limonene takes place. The slight loss of limonene that takes place during storage at ambient temperature is related only to chemical degradation, which is independent of the packaging. Type 3 packages are mainly glass and PET bottles. In flexible packages, aromabarrier polymers simultaneously used as sealing layers are sometimes more difficult to seal than polyolefins. 9.4.4 CONSEQUENCES OF FLAVOUR SCALPING
Laminated cartons used for orange juice packaging are often Type 2 packages, which permit a greater or lesser degree of flavour scalping. However, absorption into this package type does not affect the whole aroma profile but rather the nonpolar aroma compounds like limonene. Nevertheless, the loss of nonpolar aroma compounds is limited by the barrier (aluminium foil) in the laminate structure. So the question arises whether flavour scalping has a significant impact on juice quality and taste. This subject has met with controversy in the literature. Dürr et al. (see Table 9.2) have ranked the hydrocarbon fraction of orange juice aroma mainly under the desirable portion. However, they have also indicated that limonene, for instance, is a precursor for development of offodour during storage. They showed that losses of up to 40 % of limonene actually had no effect on the sensory quality of orange juice during 90 days storage at 20 °C, and suggested that limonene made a low contribution to the typical aroma of orange juice.
Type 2
In this package, having an aroma barrier and a polyolefin sealing layer in contact with product, limonene content will decrease within the first few weeks of storage due to its absorption into the sealing layer. As soon as this layer is saturated with aroma compounds, an equilibrium level will be reached and no further absorption/permeation will take place because the effective barrier (such as aluminium foil, PET, PA, EVOH) behind the sealing layer prevents further permeation through the material structure. The extent of limonene retention at equilibrium is determined in this package type by the thickness of the internal sealing layer and by the
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9.5 Aseptic versus nonaseptic packaging
Microbiological growth
Joint investigations between Tetra Pak and the Citrus Research Centre in Florida (Pieper et al. 1992) showed that flavour scalping of up to 50 % of the original concentration of limonene in orange juice has no effect on the sensory ranking in a preference hedonic scale test of quality of orange juice stored for up to 23 weeks at 4 °C. Although absorption of limonene into the inner layer of barrier packages was found not to affect the taste of the juice, additional aroma oil is sometimes added in juice preparation to compensate for any loss caused by limonene absorption, for example, when the same product is distributed in several different package types.
Aroma/odour barrier
Short shelf life (chilled), nonaseptic packages.
Oxygen barrier
Long shelf life (ambient), aseptic packages.
Fig. 9.9 Factors affecting product shelf life and their relative importance during product distribution.
9.5 Aseptic versus nonaseptic packaging For storage at ambient temperature, it is essential that: • orange juice is free of spoilage microorganisms when packed • packages do not recontaminate the product • packages provide an effective barrier against external microorganisms
oxygen barrier properties are of minor importance compared with a package where the juice is spoiled by microorganisms after 6 weeks or more. As the shelf life of aseptically packed juice is not limited by microbial action, oxygen and aroma barrier properties determine product shelf life. Figure 9.9 presents the factors that affect product shelf life and their relative importance during chilled and ambient distribution.
Since these conditions are an absolute prerequisite for storage at ambient temperature, product shelf life is not determined by microbiological factors but mainly by barrier properties against oxidative changes. For juice under chilled distribution, the situation can be more complicated. Microbial spoilage may become the limiting factor of shelf life depending on the selected heat treatment of the product, hygienic status of the packaging system and storage temperature of filled packages (2–10 °C). It is outside the scope of this section to discuss the different options with respect to the expected shelf life under chilled conditions, but it is important to understand that the requirements for other barrier properties of a package depend on whether or not product shelf life is limited by microbiological spoilage. For example, if a juice is spoiled by microbial action after 3 weeks at 4 °C, the aroma and
9.6 Different packages and packaging systems Orange juice for home consumption is sold mainly in shelf-stable or chilled form. The shelf-stable form, stored at ambient temperature, dominates all global retail markets except in the USA where chilled juice leads. Frozen concentrate for home dilution is still a common product in the USA. It is rare elsewhere because of poor quality domestic water or the inconvenience of dilution. Ready-to-drink juice from concentrate and notfrom-concentrate juice sold as shelf-stable products are pasteurised and either packaged aseptically or hot-filled. The types of orange juice sold in chilled form – freshly squeezed juice, NFC, and readyto-drink juice from concentrate – are not usually packaged aseptically or hot-filled.
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9.6 Different packages and packaging systems
Laminated carton packages are the predominant form of packaging in most countries for orange juice. One notable exception is Germany, where glass bottles are mainly used. Worldwide, glassbottles are the second most common type of container, closely followed by plastic bottles. In the USA, plastic bottles for chilled orange juice now take second place after cartons. Today, less and less juice for consumption is sold in cans, although Japan is one exception. PET bottles with added oxygen barrier have been introduced recently for ambient orange juice. The packaging preferences for fruit juices in Western Europe can be seen in Figure 9.10. This subsection describes the two major types of packages used for orange juice, laminated carton packages and bottles.
on polyester, ethylene vinyl alcohol (EVOH), and polyamide (PA). A schematic structure of laminated packaging material for orange juice cartons is shown in Figure 9.11. Depending on the packaging system used, the packaging material is delivered to the juice packer as prefabricated carton blanks or printed and creased in rolls. Oxygen-bar rier proper ties of a laminated carton package depend not only on the bar rier properties of the packaging material itself, but also on the barrier properties of strips and closures and the tightness of seals.
PE Print Liquid paperboard
9.6.1 CARTON-BASED PACKAGES
The laminated carton material normally consists of layers of paperboard coated internally and externally with polyethylene, and a barrier layer. The most commonly used barrier layer today is aluminium foil. Other barriers include SiOx
PE Barrier layer
Fig. 9.11 The structure of a laminated packaging material.
5000 4500 4000 Cartons Glass bottles Plastic bottles
Million litres
3500 3000 2500 2000 1500 1000 500 0 1996
1997
1998
1999
2000
2001
Year
Fig. 9.10 Packaging of fruit juice in Western Europe. Source: Tetra Pak
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PE
9.6 Different packages and packaging systems
The filling of juices containing floating pulp should be done continuously since separation of the juice and cells in upstream buffer tanks happens quite fast. To avoid separation, agitation of upstream tanks is sometimes car ried out. Care should be taken to prevent agitation from introducing air and gas bubbles into the juice. Carton-based packages from rolls
Packaging materials are supplied in rolls that have been printed and creased. The packaging material roll is fed into a machine where it is formed into a tube and the longitudinal seal made by a heat-sealing system. In this process, a strip is heatsealed along the inner surface of the longitudinal seal (LS) to provide protection for the different layers of packaging material from contact with product and vice versa. The oxygen-barrier properties of the longitudinal seal are important for oxygen-sensitive products such as orange juice. Some carton-based packages made from rolls are shown in Figure 9.13. Orange juice is poured into the tube and a transversal seal (TS) is made below the level of the orange juice. Alternatively, packages may be produced with a headspace by either injection of nitrogen or low-level filling. Carton-based packages with a polyethylene lid are made from roll-fed packaging material. In the packaging machine the material is folded, sealed longitudinally and cut into sleeves. The plastic tops are injection moulded and applied to the packages. After filling, the bottoms are sealed by heating elements. In an aseptic filling system, the material web is treated with hydrogen peroxide, H2O2, using either a wetting system or a deep bath system, after which the H2O2 is completely evaporated. The sterilisation, filling and sealing processes are all performed inside a sterile chamber under positive pressure. The quality of the seals is of utmost importance in aseptic systems since the entry of microorganisms should be prevented. When filling orange juice with a high content of floating pulp, special consideration should be given to the transverse sealing.
Fig. 9.12 Carton-based packages made from prefabricated blanks.
Carton-based packages from prefabricated blanks
With prefabricated systems, the blanks are die-cut and creased, and the longitudinal seal is completed at the packaging material factory. The flat blanks are delivered to the juice packing facility where they are finally shaped and sealed in the filler. Blanks to be used for chilled orange juice are handled under nonsterile conditions but steps are taken to avoid recontamination. The filling temperature should be low (4–5 °C) to minimise microbial growth. At these low temperatures the risk of foaming is higher compared with filling at higher temperature. All packages made from prefabricated blanks are filled leaving a certain amount of headspace. An inert gas like nitrogen can be used in the headspace to protect the orange juice from aerobic changes during storage. The advantages of a headspace are that pulp-containing juice can be shaken and that package sealing occurs above the product line, thus preventing floating pulp from getting trapped in the top seal.
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9.6 Different packages and packaging systems
Fig. 9.13 Carton-based packages made from rolls.
9.6.2 BOTTLES
steam. Steam injection keeps foaming to a minimum, reduces the oxygen content of the neck space and lowers the recontamination risk. Hotfilled bottles are frequently overfilled in order to ensure sterilisation of the neck by the hot product. Another possibility for neck sterilisation is to turn the bottle upside down.
Glass bottles
Glass bottles are the second most common orange juice package used worldwide. For shelf-stable orange juice in glass bottles, the most common filling method is hot filling. Aseptic filling of glass bottles at ambient temperature is of minor importance compared with hot filling. Of the package types used today for orange juice, glass bottles are normally considered to have the best oxygen barrier properties. In hot filling, the deaerated and heated juice is directly poured into cleaned bottles that are capped. The filling temperature is usually between 90 °C and 98 °C; the holding time may vary before the bottle is cooled in a tunnel. Preheating of glass bottles is necessary before filling in order to reduce the risk of glass splintering. The hot product sterilises the inside surface of the bottle, whereas bottle closures should be sterilised before they are applied to the bottle. Prior to closure the bottle neck is flushed with
Fig. 9.14 Glass bottles.
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9.6 Different packages and packaging systems
Fig. 9.15 Plastic bottles. Plastic bottles
Blow-moulded plastic bottles are an alternative to glass bottles for orange juice. The most common plastic bottles used are high-density polyethylene (HDPE) bottles and polyethylene terephtalate (PET) bottles. As HDPE has a poor oxygen bar rier, plain HDPE bottles allow relatively high oxygen ingress and are used for chilled juice of short shelf life (about 3 weeks). The oxygen bar rier can be improved by adding some polymers with better bar rier proper ties. The most common bar rier layers in HDPE bottles for orange juice are ethylene vinyl alcohol (EVOH) and polyamide (PA). These can allow ambient storage for 6 months or longer, depending on the choice and thickness of the barrier layer. HDPE bottles are fairly opaque, often pigmented, and produced by the extrusion blow-moulding (EBM) process, PET bottles were introduced in the late 1970’s and are now widely used for carbonated beverages. The application of PET bottles in the still drink segment is growing steadily. PET bottles are made by stretch blow moulding (SBM), starting with a preform. A preform is an injection-moulded PET tube closed at one end and with the finished neck at the open end.
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The stretching during blowing of the bottle gives high tensile strength and increased gas barrier to provide a lightweight bottle, and thus relatively low bottle cost. In their natural state PET bottles are transparent and colourless, but coloured bottles can be produced by adding appropriate pigments to the raw PET material. The robustness of PET bottles compared with glass is obvious, but regular PET bottles do not provide as good an oxygen barrier as glass. Barrier properties for PET bottles increase with the degree of crystallinity, which is influenced by the conditions during blow moulding and material thickness. Regular PET bottles give a shelf life for orange juice of about three to four months; large volume bottles give a longer period. Adding a barrier may extend shelf life up to 12 months or more. There are several methods for barrier addition, such as mixing the PET polymer with other compounds, coating the bottle with a barrier layer, or forming several material layers in the preform. In this case, barrier addition is more complicated than with extrusion blow-moulded bottles. PET (and HDPE for ambient storage) bottles are often filled by hot filling. Aseptic filling of PET bottles at ambient temperature requires a significantly larger investment but is increasingly gaining ground as bottlers become more experienced and the aseptic filling technologies become verified. The temperature for hot filling of orange juice in PET bottles is 84°C to 88 °C. For the material to withstand the high hot filling temperatures, relatively thick plastic and special thermal stabilisation, “heat setting”, of the bottles during stretch blow moulding are required. To withstand the vacuum created when product cools down in the bottle after filling, PET bottles for hot filling are designed with “vacuum panels” (flat surfaces on the side of the bottle) or other features that allow bottle contraction. PET bottles for aseptic filling are sterilised prior to filling with product. During sterilisation the bottles are treated with a sterilant such as hydrogen peroxide or peroxyacetic acid (PAA) and then rinsed with sterile water. PET bottles
9.6 Different packages and packaging systems
100
Temperature °C
80
60
Heat treatment for hot filling
Heat treatment for aseptic filling
40
20 Heat treatment for cold filling
0 0
5
10
15
20
25
30
Minutes
Fig. 9.16 Comparison of aseptic filling and hot-filling methods. Source: Tetra Pak
for aseptic filling are of lower weight than hot-fill bottles and do not need heat setting. This results in lower bottle cost while oxygen permeability is slightly higher. Bottles for aseptic filling allow more freedom in their design as vacuum panels or similar features are not needed.
Glass bottles have to be heated before filling and cooled down after filling by means of a cascade system, otherwise the glass will break. PET bottles have the advantage of tolerating immediate exposure to high filling temperatures and cooling more rapidly after the time needed to kill spoilage microorganisms. The quality of hot-filled orange juice compared with the quality of aseptically filled orange juice has been the subject of much discussion. Mannheim and Havkin (1981) compared the quality of aseptically filled juice to a hot-filled orange juice during storage. Their conclusions were that immediately after filling, the aseptically filled juice was judged slightly better, although differences in taste between the juices disappeared during storage. Vitamin C losses and browning were lower in the aseptically filled juice after ambient storage. Figure 9.16 shows the heat treatment to which orange juice is subjected during aseptic filling and hot filling. For aseptic filling, the pasteurised juice is quickly cooled down to filling temperature, whereas the time required to cool down hot-filled juice is dependent on the bottle size and type of tunnel cooler.
9.6.3 HOT FILLING
Hot-filling procedures used for the production of shelf-stable orange juice involve pouring the heat-treated juice, without significant cooling, directly into the package. The high temperature of the juice is used to kill microorganisms on the surfaces of packages. The time period and temperature needed will depend on: • the microbial contamination of packages and closures • the number of microorganisms in the surrounding air, production area and filling machine • the quality requirements for the product • pH value of the product • the shape of the package • the material used for packaging
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9.6 Different packages and packaging systems
9.6.4 SELECTING THE MOST APPROPRIATE PACKAGE FOR A PARTICULAR JUICE
To facilitate selecting the most appropriate packaging system for a particular juice, certain questions need to be answered. Some of these are listed below: • Which quality parameters should the packages protect and to what extent? One answer is the minimum vitamin C content at the end of product shelf life. • How long is the expected product shelf life and at what storage temperature? • How many of the parameters limiting product shelf life are left after processing? • Is dissolved oxygen present in the orange juice and to what extent? • Which oxygen barrier is needed to protect the selected quality parameters during the intended shelf life? • Is a light barrier needed? Whatever packaging system is selected, the ultimate aim must be to maintain the quality of a particular orange juice product during its defined shelf life conditions.
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10
From juice packer to consumer
In section 10 you will read about: • When and where orange juice is consumed. • Some of the major reasons why people buy orange juice. • The composition of orange nectars and still drinks.
• The three main paths of orange juice distribution from the juice packer to the retailer. • How packaged orange juice is handled at the retailer depot and sales outlet. • Primary, secondary and tertiary packaging and distribution units. • How product handling and distribution affect direct product profitability. • Who consumes what types of orange juice.
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10. Orange juice quality and categories SUMMARY Juice distribution from the juice packer to the retailer follows three main paths: the traditional path where a product reaches the retailer via a wholesaler; delivery of full pallets or roll containers directly to the retailer; and delivery of products to the retailers’ own central depots. Computer-aided product intake, storage, picking and distribution facilitate handling at the depots. Orange juice is filled into primary packaging. This is contained in secondary packaging, which can be split up into distribution units and sales units: it sometimes functions as both. Pallets of various types form the main tertiary unit for product distribution. Direct product profitability (DPP) is a measure of retailer margin contributed by a particular product. An optimal package and distribution unit, knowledge of how to handle these, high product turnover rate and low occupancy cost are essential for maximising DPP.
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The most popular fruit drink In the US more than 72 % of adults consume orange juice, and almost 50 % of the total juice volume consumed in Western Europe is orange juice. Although juice made from concentrate packed for distribution at ambient temperature remains the most popular orange juice product in Western Europe, chilled NFC is showing significant growth in many markets. Orange juice is regarded as a healthy drink and is primarily consumed in the home as part of breakfast. But new trends are making orange juice an all-day beverage available in smaller retail outlets in single-portion containers for on-the-go consumption. Orange juices constitute a wholesome alternative to many other drinks. Freshly squeezed and NFC juices have perceived properties which are very close to the original fruit. Therefore they represent the fresh taste of oranges in a convenient form. A significant volume of orange juice concentrate is used for the production of beverages having an orange flavour, such as nectars and still drinks.
10.1 Distribution of product to retailer
Truck
Truck Wholesaler depot
Truck
Juice packer Retailer
Consumer
Central retailer depot Truck
Truck
Fig. 10.1 The three main paths of orange juice distribution.
10.1 Distribution of product to retailer
The advantage for the producer is that he keeps control of distribution, which could make it difficult for competitors to penetrate his region. The advantage for the retailer is that it may be easier to get just-in-time deliveries of products with short shelf lives. However, this system results in a lot of truck traffic to the stores. Sometimes, distribution alliances are formed between producers of different products, e.g. chilled juice and yoghurt.
The production process at the packer involves taking liquid juice and packing it into consumer packages. In turn, these are packed into secondary units (e.g. cardboard trays and crates), and later on in tertiary units (e.g. pallets). To facilitate handling and distribution for both the juice packer and retailer, it helps if packages are “iso-modular”, i.e. they can be efficiently packed on standard pallets, half pallets and quarter pallets. In the case of chilled juice, the secondary package is frequently plastic crates or roll containers. If the package is returnable, a reverse stream of empty packages occurs. The three main paths of orange juice distribution from the juice packer to the retailer are briefly described below.
10.1.2 DELIVERY THROUGH WHOLESALERS
The traditional distribution chain is where a producer sells products to a wholesaler, who in turn sells them to the retailer. The wholesaler has a central depot from which deliveries to a number of stores are effected. The advantage for the producer is that it is easier to deal with one customer than a number of stores, a fact that allows the producer to gain a wider geographic distribution area. This distribution system is also more rationalised than delivery directly to all stores.
10.1.1 DELIVERY DIRECTLY TO THE RETAIL STORE
The producer, in this case the juice packer such as a dairy, delivers full pallets or roll containers directly to the retailer. This path is often found with chilled products.
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10.1 Distribution of product to retailer
Fig. 10.2 Handling at the retailer depot.
and entered into a computer system. The computer system allots each pallet a bar-code label bearing product information and an intermediate storage location (2). Fork-lift truck drivers then scan the bar code and the destination of each pallet is shown on a screen. The pallets are put in racks, which can be several levels high (3). When the number of product trays at the picking line level drops below a predefined amount, order execution personnel enter a request for replenishment in the computer system. The closest forklift driver receives the location and destination of a pallet and executes the request (4). Orders from retailers are printed on a sheet of labels which functions as a work order for order personnel, who drive along the picking line route and place trays of products on roll containers, or pallets in some cases (5). The sheet of labels contains an end-label which is scanned into the computer system. A location in the outgoing goods area is thus obtained for the roll containers, which are then put in numbered fields so that deliveries to retailers near each other can be grouped together (6). At the outgoing goods counter, the delivery truck driver receives a delivery document which specifies each roll container and its destination (7).
10.1.3 DELIVERY TO A RETAILER’S CENTRAL DEPOT
In many countries there is a growing trend for retailers to take charge of the wholesaler function through their own central depots. This allows the shops to take frequent deliveries of all products in one or few trucks, which leads to small storage areas and maximal shop area. The resulting reduced truck traffic is cost-effective and entails less environmental impact. The time needed to receive and check products is also reduced. As retailers grow larger, this alternative will become more common. Improvement of bar-coding technology and the trend towards centralised purchasing is also driving this development. Deliveries to the depot are handled by the producer directly or by a transport company, in which case mixed deliveries are common, i.e. the truck picks up goods from other producers as well. Deliveries generally take place once a week for most products, but high volume items may be delivered twice or even three times a week. The handling steps at the depot are briefly explained below with the help of Figure 10.2. Pallets are unloaded from a truck in the incoming goods area at the warehouse (1). All deliveries are checked against the delivery document
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10.2 Orange juice at the retailer
Shrink-wrap unit Corrugated cardboard tray
Wraparound unit
Fig. 10.3 Typical one-way secondary packaging.
10.2 Orange juice at the retailer
10.2.1 DISTRIBUTION UNITS
In general, juice distributed at ambient temperature comprises one-way systems and juice distributed chilled comprises returnable systems. This is mainly in accordance with the shorter shelf life of chilled juice and with established distribution systems that exist in some countries. One-way secondary packaging (see Figure 10.3) can be split up into distribution units and sales units; it sometimes functions as both. Typical distribution units are cardboard trays, wraparound boxes, sleeves and film-wrapped units. Cardboard offers the best protection for the packages, as boxes more than trays. Distribution units in film are not so commonly used for juice. Examples of sales units intended for consumers who buy more than one package at a time are board-wrapped units, sleeves and film-wrapped units. The choice here depends on the purpose of the unit, i.e. simply to sell a larger quantity of packages in one unit or whether it is also used to enhance the image of the juice product. Examples of returnable secondary packaging are plastic crates in various shapes and sizes, and roll containers (see Figure 10.4). In some countries, roll containers and crates are used all the way from the juice packer to the chilled sector in the store. In other countries, the units are unloaded when they ar rive at the store for storage and display purposes.
Because of its importance to the consumer, orange juice is one of the more important pro-ducts for the retailer to keep in stock. In many countries, fruit juice is distributed both chilled and at ambient temperature. This can make it difficult for the retailer to display juice as one category and for the consumer to make a purchase decision.
Roll container
Plastic crate
Fig. 10.4 Typical returnable packaging.
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10.2 Orange juice at the retailer
10.2.2 HANDLING AT THE RETAILER
The retailer handles full pallets, roll containers, secondary units (trays) and individual packages. For high volume or promotional items, the most efficient unit is a full pallet. With the averagesized retailer it is more common to handle secondary units which are placed directly onto shelves or opened to allow individual packages to be stacked onto shelves. Handling at the retailer can be explained with the help of Figure 10.6. The delivery truck unloads roll containers or pallets and places them in the shop’s storage area (1). The delivery is checked against the delivery document to confirm that the retailer has received what he ordered (2). A roll container may hold shelf-stable products destined for different departments of the store (though chilled products are normally packed separately). Therefore products have to be sorted according to department (3). Products are then transported out to the display area (4) where they are put on shelves (5). Transport packaging (mainly for shelf-stable products) is removed and separated for later recycling. The final step at the retailer is the checkout (6).
Fig. 10.5 Pallets of various types form the main tertiary packaging units.
Pallets of various types of material and sizes form the main tertiary unit used for transportation of cardboard units, film-wrapped units and crates (see Figure 10.5). The most common pallets used are 800x1,200 mm, 1,000x1,200 mm and 40x48". Half pallets (800x600 mm) and quarter pallets (400x600 mm) are also used. Another type of tertiary unit is the roll container.
Storage area
Display area
Figure 10.6 Handling at the retailer.
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10.2 Orange juice at the retailer
DPP: Direct product profitability
During the handling steps from juice producer to consumer, a product which is easy to handle and efficient to transport has an advantage because this will translate into a better margin for the retailer. This is what DPP measures. The gross margin is adjusted for all costs added by the product, including transport, occupied shelfspace, time on the shelf and product handling (see Figure 10.7) The variables that affect DPP cover the package itself, more importantly the secondary package, e.g. trays and boxes, which are the units handled up to the final placement of product on the retailer shelf. When on the shelf, the product turnover rate and occupancy cost will also affect the DPP.
Sales price
A package with a good DPP will be attractive to the retailer. Even if the gross margin is satisfactory for the product, if the direct product cost cannot be optimised the DPP will be smaller. Therefore it is important to have an optimal package and distribution unit, as well as knowledge of how to handle them, in order to minimise the direct product costs (DPC). It is also important that the package is designed to utilise the shelf space in the best possible way.
Gross margin Adjusted gross margin
Costs of goods sold
Other direct revenues
Direct product profit Direct product costs
Warehouse direct costs Transport direct costs Store direct costs
Fig. 10.7 The DPP model.
Retunables costs
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10.3 The orange juice consumer
Large marketing efforts by some of the major juice brands have increased consumers’ awareness of the NFC category. Consumers now also recognise that drinks with low juice content, although clearly labelled high in vitamin C, are not the same as pure juice. Freshly squeezed orange juice is a product category familiar to consumers, but it is often too expensive to merit consumption in large quantities. Short shelf life is a drawback compared to pasteurised NFC. In the US orange juice market there has been a continuous shift in consumer preference regarding the main orange juice categories. NFC has grown steadily to a 45 % share in 2003, while sales of frozen concentrate have gradually declined from a dominant position to about 10 % of retail sales based on juice volume. Orange juice made from concentrate has declined slowly over the past decade and was overtaken by NFC in 2002.
10.3 The orange juice consumer Orange juice is a natural part of the daily diet of many people in the industrialised world. More than 72 % of US adults consume orange juice, and of all beverage types only milk is consumed by more people. Orange dominates the juice market with a 60 % market share of packaged juices in the US. Apple juice comes second with a 15 % share. For Western European consumers, orange is still the dominant flavour, with some 45 % of the total packaged juice volume consumed as orange juice in 2003 (Figure 10.8). Apple is the second flavour with 20 % of the overall volume share thanks to its popularity in Germany, which is the largest juice market in Europe. However, multivitamin blends as well as tropical blends show strong growth. The multivitamin-added juice blends appeal to health-conscious European consumers.Moreover, blending satisfies the increasing demands of consumers for new pleasing juice flavours. In other geographical regions, such as South America and Asia/Pacific, orange juice is just as popular with more than a 50 % volume share of packaged juice.
Other fruits 21%
10.3.1 REGIONAL PREFERENCES FOR JUICE CATEGORIES
Most consumers link the term “juice” intimately with orange juice, which is the first flavour mentioned when asked. However, the many brands, qualities and package formats for juices have led to some consumer confusion. Separating juices from juice drinks, chilled storage from storage at ambient temperature, not-from-concentrate from reconstituted juice is very difficult for many shoppers. Considering the importance of the juice segment to the average consumer, people know surprisingly little about juice categories.
Tropical, multivit. & other blends 12%
Orange 45%
Apple 22%
Fig. 10.8 Volumes of different flavours of packaged juice consumed in Western Europe, 2003. Source: Euromonitor
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10.3 The orange juice consumer
60 RTD from concentrate
% vol as SSE
50 40
NFC
30 20 Frozen concentrate
10 0 95/96
96/97
97/98
98/99
99/00
00/01
01/02
02/03
Season
Fig. 10.9 Retail sales of orange juice categories in the US. Source: Florida Department of Citrus.
The share of retail sales is shown in Figure 10.9, which is based on Nielsen statistics for all retail outlets. Practically all RTD orange juice in the US is distributed chilled (4 °C). A recent trend in Western Europe is that chilled orange juice is increasing in popularity because of its perceived better quality, supported by the presence of NFC juice in the chilled segment. NFC now accounts for more than 10 % of orange juice consumption. Aseptically packed concentrate for home dilution is found in some markets in northern Europe. However, the dominant product is juice made from concentrate packed for distribution at ambient temperature. In Europe, orange juice faces competition from multivitamin juice blends. And beverages with lower juice and energy content but containing added vitamins are trying to take a bigger share of the health-conscious consumer market. The orange juice consumer in mature juice markets has an ever-increasing choice of orange juice with a variety of added nutrients such as calcium. Such fortified juices satisfy the nutrient needs for an “on-the-go breakfast”. Smoothies, a blend of fruit juice and milk or yoghurt, is a recent entry to the juice market that gives consumers a further alternative for consuming fruit juice as a replacement for skipped meals. In the effort of making orange juice an all-day beverage for consumption outside the home, it is
increasingly common for the orange juice drinker to find single-serve container sizes sold in a variety of outlets and convenience stores. In south and central America, where fresh fruit is available at affordable prices, home-squeezed orange juice is most common. Purchased beverages are mainly juice drinks. In contrast to Europe, there is a close correlation between income levels and fruit content of purchased beverages; with increasing income there is a shift towards nectar and then on to 100 % juice. Health consciousness in all income groups leads to the replacement of carbonates with juice beverages. In the Asia and Pacific region, consumer behaviour differs between mature and developing markets. In mature markets, such as Japan and Australia, consumers prefer to buy 100 % orange juice, whereas in developing markets purchased beverages are predominantly low-content juice drinks. Fresh fruit is usually available at low cost. Also in these markets there is a trend to move to higher fruit content with increasing disposable incomes. In urban areas of China, a rapidly growing group of consumers are asking for packaged orange juice. The following sections refer mainly to North America and Western Europe, where more than 80 % of packaged orange juice is consumed. The US market influences consumer trends in other markets.
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10.3 The orange juice consumer
10.3.2 WHO BUYS JUICE IN THE USA
10.3.3 WHEN ORANGE JUICE IS CONSUMED
Several demographic studies of orange juice consumers in the US have been made over the years. Orange juice is consumed throughout the US and is fairly representative of the fruit beverage segment, including nectars and juice drinks. The results for 2000 show that somewhat more women than men consume orange juice, 73 % of all women compared with 71 % of men. Young adults drink orange juice to a lesser degree than average for the US population. On the other hand, orange juice penetration in the elderly part of the community (age 65+) has increased compared to previous studies. Marketing that targets the elderly, and emphasises the health benefits of orange juice, ensures that consumption is maintained in this age group. Orange juice penetration is slightly lower for black and Spanish-speaking Americans than for other ethnic groups (Figure 10.10).
Orange juice is closely linked to the breakfast meal, whereas apple juice is more widely consumed on other occasions during the day. The reason for this, apart from pure habit, is probably that orange juice is not as thirst-quenching as alternative drinks. On the contrary, some consumers feel that orange juice makes you thirstier after drinking it. However, many consumers experience an “energy-kick” from orange juice, which may be particularly needed in the morning. Alongside the traditional consumption of orange juice at breakfast, bought in family-size packages from large retail stores, the trend in the USA and Europe is to promote orange juice as an all-day beverage. Available in single-serve sizes in, e.g. convenience stores and petrol stations, it is a healthier alternative to carbonated soft drinks.
50%
55%
60%
65%
Sex
Men Women 18-24 25-34
Age
35-44 45-54 55-64 65+
Ethnic
White Black Hispanic Other
Fig. 10.10 Orange juice penetration in the USA, 2000. Source: Beverage Marketing
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70%
75%
80%
10.3 The orange juice consumer
0%
20%
40%
60%
80%
100%
United Kingdom Norway Austria Ireland Denmark France Belgium Netherlands Switzerland Italy Spain Finland Cyprus Sweden Germany Portugal Greece West Europe in-home
out-of-home
Fig. 10.11 The Western European juice and nectar market split into in-home and out-of-home consumption, 2000. Source: Tetra Pak
on private and public transport, and in other locations outside of the home. Thus orange juice is promoted as an alternative to carbonated soft drinks and waters for adult consumers. Consumption in restaurants, cafés and bars is also becoming more common now that orange juice in no longer considered just a breakfast drink. In-home consumption of juices and nectars (all flavours) averages 78 % for Western Europe, which is high compared with alcoholic beverages (55 %) and carbonated soft drinks (66 %), but low compared with milk (88 %). National averages for in-home consumption range from 65 % for Greece and Portugal to 95 % for Norway and the UK (Figure 10.11).
10.3.4 WHERE ORANGE JUICE IS CONSUMED
Orange juice is still very much a “home” product purchased in normal grocery outlets. Part of this relates to the fact that it is traditionally regarded as a breakfast drink and breakfast is usually eaten in the home. But the trend in the US, closely followed by the UK, is that fewer people have breakfast at home. To cater for the new consumer needs orange juice is now available in more outlet points, like convenience stores and petrol stations. The ”on-the-go” consumption of orange juice is further promoted by an increase in small-size containers. This is evidence of the juice producers’ strategy since the late 1990’s in the US and Europe of encouraging juice drinking in offices,
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10.3 The orange juice consumer
10.3.5 WHY PEOPLE BUY ORANGE JUICE
Good for children
Parents feel that pure juice is a healthy alternative to carbonated soft drinks for their children. Even if most mothers consume juice themselves, children in the home are an important driving force behind purchases. In fact, orange juice has a much higher market penetration with families having children than with single adults.
Health/vitamins
Consumers recognise orange juice as an important source of vitamin C, and a very natural and “true” product which closely resembles the fresh fruit. This is often in contrast with still drinks and carbonates where high added sugar content is of concern. Moreover, among other nutrients, orange juice contains folic acid, which may be important for pregnant women as it helps to reduce the risk of certain birth defects. Antioxidants and other constituents beneficial to health is a good reason for the elderly to continue consuming orange juice. Indeed, consumption is increasing within this age group in the US. In addition to nutrients naturally present in orange juice, consumers can now find orange juice products enriched with a variety of vitamins and minerals. Calcium fortification can be important if a person’s diet includes few dairy products. Orange juice with added plant sterols that help to reduce cholesterol levels was recently introduced in the US, enhancing health benefits even further.
Natural alternative to other drinks
As a refreshment drink, juice is definitely seen as healthier than carbonated soft drinks and it has more nutritional value than mineral water. On social occasions, orange juice is often served as an acceptable alternative to alcoholic drinks. Because orange juices are closely governed by regulations, they are also considered as a natural alternative to some other types of drink. Habit/traditional breakfast drink
In many markets the traditional breakfast includes a glass of juice, especially orange juice. Therefore it is regularly purchased and consumed as a matter of routine. Fruit substitute
Orange juice can provide the same benefits as eating a fresh orange without being as messy to consume. Freshly squeezed and NFC have properties which are even closer to the original fruit. Juices with added fruit cells are perceived as tasting similar to fresh oranges.
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10.4 Orange nectars and orange drinks
10.4 Orange nectars and orange drinks
10.4.2 STILL FRUIT DRINKS
If nectars can be seen as an alternative to 100 % juice, still fruit drinks are more of an alternative to carbonated soft drinks. Often high in sugar and low in juice content, still fruit drinks are frequently sold in smaller packages (200–300 ml) for “on-the-go” consumption, but larger family-size packages of 2 litres (64 fluid oz) are also common. Many still drink products have a “kids” image since many of these products are directly targeted at children, but there are also some products for adults with a premium profile. There is little specific regulation of still fruit drinks, but many countries demand that the juice content be stated. Some countries have minimum juice content requirements (e.g. 5 %) for fruit drinks. In the UK, the manufacturer may not imply that a product is a fruit drink if it does not meet the required juice content level unless the suffix “-ade” is linked to the fruit name, e.g. lemonade, or if the fruit name is followed by the word “flavour”, e.g. “orange flavour drink”. In Switzerland, manufacturers are not allowed to use pictures of fruits on fruit drink packages. Recent product development in fortified fruit drinks, containing a high juice content (20 % and more) and added vitamin blends, such as ACE, has effectively raised the health profile of fruit drinks. With a lower energy content than 100 % fruit juices, these beverages are aimed at promoting health at a reduced calorie intake.
In many markets, a substantial share of orange juice concentrate is used for production of other beverages having an orange flavour. The names and definitions of these beverages vary between markets, but in general we speak about nectars and still drinks. Fruit nectars usually have a juice content of 25 % to 99 % (50–99 % for orange nectars in the EU), and beverages with a fruit juice content below 25 % are generally called fruit drinks or still drinks. In markets where nectars are popular, e.g. Germany and France, some consumers see nectars as a superior product than 100 % juice. This is because the word “nectar” has a very positive association. 10.4.1 FRUIT NECTARS
Originally, nectars signified beverages from fruits which were too viscous to be consumed in a 100 % form, e.g. apricots, peaches and pears. Consequently, water and sugar were added to dilute the purée and make it more drinkable. Today, the term nectars has been applied to fruit beverages with less than 100 % juice content, with basically only water and sugar being allowed as additives to the fruit juice product. The fruit juice used for nectar production may be as juice, concentrate or powder. For orange nectars, a minimum of 50 % juice content applies in the EU. Moreover, the fruit juice content has to be declared on the package. Sugar and honey addition is allowed up to 20 % final weight: sugar may be replaced by sweeteners for low-energy fruit nectars. Nectars (or fruit juice drinks) can be seen as a less expensive substitute for 100 % juice, frequently bought in larger packages (750 ml and higher) by less affluent consumers. Low-energy nectars appeal to consumers who want the benefits of fruit juice but would like to reduce their calorie intake. Their increased popularity accords with the awareness that high-energy beverages may contribute significantly to the calorie content of diets.
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10.4 Orange nectars and orange drinks
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11
Standards and regulations
In section 11 you will read about: • Standards governing juice composition and labelling in the USA, EU member states and some other major regions around the world. • The Codex Alimentarius Commission set up by the FAO and WHO to implement the Joint FAO/WHO Food Standards Programme.
• The problem of orange juice adulteration and why it is still carried out. • The measures taken to prevent the adulteration of orange juice and check its authenticity. • The major analytical methods used to detect adulterated juice.
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11. Standards and regulations Summary In the USA, the standards covering the composition of juices and juice products, and their labelling, are governed by the FDA and USDA. Canada has similar regulations. The fruit juice industry in EU countries is guided by both compulsory directives and recommendations. Other major juiceimporting regions also have a mixture of obligatory and voluntary standards to control imported food products. The Codex Alimentarius Commission was set up by the FAO and WHO to protect the health of consumers, to ensure fair practices in the food trade, and to promote international trade in food.
Combating adulteration Because the monetary value of the fruit juice market is so enormous, juice adulteration is common. Most countries implement a number of measures to discover and prevent the adulteration of orange juice, and to check its authenticity, that is, its declared origin and content. In Europe the AIJN Code of Practice provides standards for evaluation of identity and authenticity for juices. Today, analytical methods can detect all three of the most commonly used juice adulterants – sugar cane, sugar beet and corn syrup.
11.1 Standards governing juice composition and labelling
Regulations governing direct juice, or NFC, in principle require that nothing should be removed or added during juice extraction and further processing of the juice. In the USA this is interpreted to mean that there may be no removal of water or redilution of NFC, while it is acceptable to remove and later add back, for example, flavour fractions. For reconstituted orange juice, water should be added back to the minimum concentration defined in the standard used in a country. Essences should be added back to restore flavours, and pulp may be added to achieve the desired properties of the final juice product. The revised EU Directive for fruit juices (2001) specifies orange juice to be extracted by mechanical means but allows addition of water- extracted juice to juice made from concentrate. This means that pulp wash may be added in-line to the orange juice stream before concentration. However, addition is not permitted to direct juice or NFC. The previous Fruit Juice Directive (1993) did not allow for any water-extracted juice.
Many countries have several regulations governing fruit juices. These regulations typically cover juice origin, processing methods and the composition of orange juice. Although attempts are continually being made to harmonise the legislation between different global trading blocs aimed at facilitating juice production and trade, several significant differences between regulations still remain. Moreover, regulations will continue to change as world standards evolve. In the European Union and many other countries, the term orange juice may only be used for juice extracted from sweet oranges, Citrus sinensis. In the USA, however, regulations allow for up to 10 % of tangerine or hybrid orange/ tangerine juice to be included in orange juice. These juices can improve the colour and flavour of blended juice.
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11.1 Standards governing juice composition and labelling
Another change in the EU fruit juice Directive is that debittering (removal of limonin) is authorised, provided that the composition of other compounds in the orange juice, such as acids and sugars, is not significantly affected. The mentioned changes brings EU regulations more in line with those in the USA, Brazil and several other countries where in-line pulp wash addition and debittering is permitted. In the European Union, legislation covering fruit juices and fruit nectars is based on Council Directive 2001/112/EC concerning fruit juices and certain similar products. Some specific labelling requirements are given in the Fruit Juice Directive. Apart from this, more general EU food legislation like the directives on labelling and on additives also apply to fruit juices. In addition to the EU Council Directives, the fruit juice industries in individual EU countries must follow their own national fruit juice regulations. The EU stipulates that local regulations should not include provisions that may create barriers to the free movement of products.
The Juice Products Association (JPA, a merger of the National Juice Products Association and the Processed Apples Institute), whose members are mainly drawn from North, Central and South America, has stated that they would like to see the USDA standards covering the grade and quality of orange juice to be applicable throughout the major citrus juice producing countries. The JPA even suggests that USDA standards should be adopted as a worldwide harmonised standard. An overview of the most important aspects of legislation in the US, EU and certain other countries is given below. More detailed descriptions can be found in publications listed in Section 14, Further Reading. 11.1.1 THE USA AND CANADA
For the USA, the standards covering the composition of juices and juice products are found in FDA regulations entitled Code of Federal Regulations, Title 21. Standardised products include different types of orange juice, namely canned, frozen, pasteurised, from concentrate, frozen concentrate, orange juices for manufacturing and orange juice with preservatives. The first types of orange juices are sold directly to the consumer, while the standards for orange juice for manufacturing and orange juice with preservatives cover products intended for further processing. Like orange juice intended for retail, orange juice for manufacturing is derived from unfermented oranges except that its Brix and Brix:acid ratio may be lower than specified for retail juice. Labelling requirements include the declaration of any sweeteners added and the addition of orange concentrate to modify the solid content as permitted by the standard. Juice may be heattreated to reduce enzyme or microbial activity. The success and acceptance of the FDA standards for orange juice identity is evident considering that since they were introduced in the 1960’s, they have only been amended twice, once to allow the removal of undesirable bitterness, and secondly to allow the use of juice from the Amber sweet orange.
are continually “Attempts being made to harmonise the legislation between different global trading blocs
”
The Association of the Industry of Juices and Nectars from Fruits and Vegetables of the European Economic Community (AIJN) published a “Code of practice for the evaluation of fruit and vegetable juices” in 1993. This is a more detailed guideline, including values for a large number of quality, authenticity and identity parameters that the fruit juice industry should adhere to. The Code of Practice is increasingly used also outside EU. In the USA, the standards of orange juice identity are enforced by the Food and Drug Administration (FDA), whereas the standards for orange juice grades (quality) are enforced by the United States Department of Agriculture (USDA).
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11.1 Standards governing juice composition and labelling
The grade standards for fruit juices are issued by the USDA Agricultural Marketing Services. Grade standards concern product quality and should therefore be understood by anyone exporting products to the USA. The terms “Fancy” or “Grade A” may only be used on products meeting the specifications defined for such grades by the USDA. The current grade standards for orange juice became effective in 1983. As an example, to be labelled USDA Grade A, orange juice produced in Florida must meet the quality requirements shown in Table 11.1. The quality factors are measured on a 100-point scale. If the total score is above the limit but one of the scores does not meet the Grade A requirements, the juice may not be labelled Grade A. (Table 11.1 concerns orange juice from Florida. Some of the values differ for orange juice originating from other states such as California and Arizona.) In Canada, the Canadian Food and Drugs Regulations include standards for a number of juices including orange. These, as in the USA, strictly control the composition, quality and labelling of a range of orange juice products.
11.1.2 THE EUROPEAN UNION
The fruit juice industry in EU countries is guided by both compulsory directives and recommendations. A directive is a law drawn up by the European Union. Obligatory regulations comprise:
a) National fruit juice regulations that are in force in respective EU countries. b) Council Directive 2001/112/EC covering fruit juices and certain similar products. It was implemented by member states by July 2003 replacing Directive 93/77/EEC. The revision was undertaken in order to make the rules on manufacturing and marketing conditions more accessible. In many cases, national fruit juice regulations are similar in content to the EU Fruit Juice Directive. The main areas covered by the Directive for fruit juices are: • definitions of products and authorised processes and treatments during their manufacture • permitted ingredients • certain labelling requirements for raw material and final products
TABLE 11.1 USDA GRADE A ORANGE JUICE PRODUCTS Orange juice Analytical factors °Brix Ratio (Brix:acid) Recoverable oil % vol. Quality factors Appearance Reconstitution Colour Flavour Defects Total score
NFC
From concentrate
min. 11.0 12.5–20.5 max. 0.035
min. 11.8 12.5–20.5 max. 0.035
fresh orange juice —— very good, min. 36 points very good, min. 36 points practically free, min. 18 points
fresh orange juice reconstitutes properly very good, min. 36 points very good, min. 36 points practically free, min. 18 points
min. 90 points
min. 90 points
Source: USDA
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11.1 Standards governing juice composition and labelling
Fruit juice is defined as the product obtained from fruit, fermentable but unfermented, having the characteristic colour, flavour and taste typical of the fruit from which it comes. Flavour, pulp and cells separated during processing may be restored to the same juice. The plain term “fruit juice” refers only to juice that has not been concentrated (NFC or direct juice). Reconstituted juice is referred to as fruit juice from concentrate. This product must have sensory and analytical characteristics at least equivalent to those of an average type of juice obtained from the same kind of fruit. Only certain ingredients and additives may be added to orange juice. The addition of vitamins is permitted in some EU countries, and under the fruit juice Directive EU countries may follow different rules provided that it does not prevent free movement of products within the EU. Harmonised regulations regarding addition of vitamins and minerals to fruit juice are proposed to be part of horizontal legislation on food additives.
fruit juice industry in EU “The countries is guided by both compulsory directives and recommendations
”
Sugar may be added up to 15 g/l orange juice for balancing acidity without having to be declared “sweetened” on the label. Nevertheless, declaration is required in the ingredient list. If the amount of sugar added for sweetness exceeds 15 g/l, it must be declared on the label along with the term “sweetened”, although the Brix values are not specified. Lemon juice may be added up to 3 g/l as citric acid to regulate acidity. However, combined addition of both sugar and acid is not permitted.
The new EU Fruit Juice Directive 2001/112/EC was published in 2001 based on a revised proposal approved in 1996. As mentioned above, it allows the addition of pulp wash to orange juice made from concentrate but not to direct juice, and the removal of limonin from orange juice. The new directive is simplified to avoid statements that are covered in other EU horizontal legislations such as the labelling directive (2000/13/EC) and food additive directives. While the Fruit Juice Directive is a vertical directive the trend is for horizontal directives that can be applied more generally and for several foodstuffs. Recommended guidelines
Recommendations are given by the Association of the Industry of Juices and Nectars (AIJN) from Fruits and Vegetables of the European Union. This organisation is based in Brussels although it is independent of the EU. An expert committee within the AIJN has established a “Code of practice for the evaluation of fruit and vegetable juices” published in 1993. Members of the expert committee are selected for their expertise and come from different countries, fruit juice companies, institutes and laboratories upon recommendation of AIJN members. Local quality and authenticity standards from European countries are incorporated in the Code of Practice. The code of practice developed by the AIJN states the following with regard to orange juice: • Orange juice is obtained from mature and sound fruit, extracted by mechanical processes and is treated by physical means • Orange juice is produced from Citrus sinensis (L) Osbeck and includes blood oranges • Floating cells may be re-added to juice • Specific conditions are to be fulfilled for in-line water extraction
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11.1 Standards governing juice composition and labelling
packaged food that is sold in Australia and New Zealand, and imported food must comply with the regulations. The food standards have the force of law and are Direct Reconstituted enforced by the two governments. Properties juice juice Orange juice is covered by the standRelative density 20/20 min. 1.040 min. 1.045 Corresponding °Brix min.10 min. 11.2 ards for fruit juice and vegetable juice. The standards include products that have been concentrated and later reconstituted with Direct juice Properties / Reconstituted juice water to a concentration consistent with L-ascorbic acid (vit. C) that of the undiluted juice from which it at end of shelf life, mg/l min. 200 was made. Orange juice is defined as the juice coming from the endocarp of mature Volatile oils, ml/l max. 0.3 Hydroxymethylfurfural (HMF), mg/l max. 10 and sound oranges of Citrus sinensis (L) Volatile acid as acetic acid, g/l* max. 0.4 Osbeck. Orange juice may include up to Ethanol, g/l max. 3.0 10 % mandarin or tangelo juice. Sugar D/L Lactic acid, g/l max. 0.2 Arsenic and heavy metals, mg/l max 0.01–5.0 may be added up to 40 g per kg product (various values) without the product being considered * Indication of hygiene, not juice acidity. sweetened. If more sugar is added, this Source: Reference guideline for orange juice, AIJN Code of Practice, 2003 must be indicated with the term “sweetened orange juice”. Juice derived from The AIJN Code of Practice includes reference concentrate must also be declared. guidelines (i.e. guidelines for what is considered Latin America an acceptable juice) for different fruit juices. The In most Latin American countries the control guidelines give both criteria that are absolute reof food products is governed by the Ministry of quirements as regards the quality of a juice, and Health or equivalent institution. Today, there is other criteria to be used to check the identity and a general trend towards harmonising food legisauthenticity of juice. lation in the region. MERCOSUR, the Southern The reference guidelines for orange juice Common Market, with member states of Brazil, were revised in 2003. Absolute requirements Argentina, Uruguay and Paraguay, has developed for some of the quality parameters are given in common food labelling regulations. ICAITI, a Table 11.2. standards organisation based in Guatemala, issues a wide range of food-related standards voluntarily 11.1.3 OTHER MAJOR REGIONS applicable in the Central American Common MarAND COUNTRIES ket countries of Guatemala, Costa Rica, Honduras, Nicaragua and El Salvador. Australia and New Zealand Comprehensive standards of fruit juices can Fruit juice and other food regulations differed be found in Argentina, Brazil, Colombia, the between Australia and New Zealand. But based Dominican Republic, Ecuador, Mexico, Uruguay, on a treaty established in 1995, the two countries Venezuela and countries of the Central American have jointly developed uniform food standards, the Common Market. These standards vary in scope Australian New Zealand Food Standards Code. and detail. Other countries, for example, Cuba, It was presented in 2000 and remained as Chile, Panama and Peru have no standards for an alternative to existing food regulations until fruit juice composition although the use of adDecember 2002 when it became the sole food ditives is controlled. code for both countries. The code applies to all TABLE 11.2 AIJN QUALITY REQUIREMENTS FOR ORANGE JUICE
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11.1 Standards governing juice composition and labelling
Middle East
11.1.4 FRUIT JUICE STANDARDS OF CODEX ALIMENTARIUS
Middle East countries have a mixture of obligatory and voluntary standards to control imported food products. Lebanon, Saudi Arabia, Jordan, Kuwait and Israel are some of the countries with mandatory standards for fruit juice. Harmonisation of food law in the region by means of Gulf Standards issued by the Gulf Cooperation Council (GCC) is in progress. The GCC comprises Saudi Arabia, Kuwait, the United Arab Emirates, Oman, Bahrain and Qatar. Where national standards are non-existent, most countries will normally accept products that comply with standards drawn up by the Codex Alimentarius Commission (CAC, see below).
The Codex Alimentarius Commission is a joint body set up by the Food and Agricultural Organisation (FAO) and World Health Organisation (WHO) in 1962 to implement the Joint FAO/WHO Food Standards Programme. This was carried out to protect the health of consumers, to ensure fair practices in the food trade, and to promote international trade in food. Member governments of the United Nations are involved in producing specific recommendations for standards covering food. Certain countries, for example some in Latin America and the Middle East, may accept Codex standards as official legislation if they have no national regulations or as an addition to national law. Trade blocs like the European Union also consider Codex standards when drawing up their own legislation. Most of the Codex standards covering fruit juices and concentrated fruit juices date from 1981. In 1992, the various standards for fruit juices and nectars were reissued in volume 6, Codex Alimentarius 1992. This contains standards defining juice products, their composition and quality factors, and regulations covering food additives, contaminants, hygiene, weight of product in containers, and labelling requirements. Analytical methods and sampling are also defined. A revision of the fruit juice standards is foreseen in 2005. Codex standard 45-1981 (from 1981) applies to orange juice. It describes it as the juice obtained by a mechanical process from the endocarp of oranges [Citrus sinensis (L.) Osbeck] preserved exclusively by physical means. It may contain up to 10 % mandarin juice. Minimum °Brix is 10 for direct juice and 11 for orange juice made from concentrate. Natural volatile orange juice components may be restored to any orange juice from which such have been removed.
Far East
Countries in the Far East have both guidelines and legally enforceable standards with regard to food quality and composition. Japan has standards covering additives, labelling requirements, purity criteria and testing methods. There is no standard of composition, therefore juice imports to Japan are not restricted by minimum levels of fruit content. However, in practice, Japanese Agricultural Standards are used to guarantee the quality of both imported and domestic processed foods. Other countries that regulate the quality of fruit juices are India, Indonesia, Malaysia, The Philippines, Pakistan, Singapore and South Korea. On the other hand, China, Taiwan and Thailand, for example, have no standards for composition but have detailed regulations for additives. There seems to be no attempt at harmonising legislation in the region.
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11.2 The problem of adulteration
11.2 The problem of adulteration
The term “adulteration” is used to describe the addition of materials not derived from citrus fruit. This includes the addition of water, sucrose and citric acid to maintain the soluble-solids content. On the other hand, the term “sophistication” is used to describe the use of other citrus products to extend or attempt to mimic genuine juice. Nonorange citrus juices, orange pulp wash and other matter derived from peel, rag or seeds constitute sophistication.
Because the monetary value of the fruit juice market is so enormous, juice adulteration is a common feature of commercial life. For orange juice, the term “adulteration” means the addition of nonorange materials to products that are labelled and sold as orange juice. The value of orange juice is such that even modest adulteration can result in large profits, something which encourages fraud among both producers and those handling concentrate for reconstitution and packaging. Any importing country can be affected, particularly when there is a shortage of orange juice supply. The problem of juice adulteration is seldom related to health risk, but primarily related to fraudulent practices. Although there may be a slight reduction in juice quality, the same decline in quality can result from poor processing conditions. The issue at stake is that someone is making a lot of money by adding cheap materials such as sugar, acid and colour to juice in order to cheat the consumer into paying too much for what is thought to be a premium product. When checks on quality are inadequate or unenforced, this inevitably leads to a greater degree of adulteration. Consumers should be protected from such fraud by regulatory authorities using their power to ensure that the composition, quality and labelling of orange juice are strictly controlled. Responsible authorities in every producing country and importing country deplore adulteration. Therefore, most take active steps to discover and prevent it, and to ensure that orange juice complies with the relevant standards applicable. The aim of most work on safeguarding the authenticity of orange juice is essentially to make adulteration so expensive that it is no longer attractive. It should also be noted that adulteration cannot be considered contamination. Unlike contamination, which is often harmful to health, the materials unlawfully added to juice are so like the juice’s natural constituents that they cannot be regarded as contaminants in the accepted sense.
11.2.1 PROTECTING THE CONSUMER
A number of measures are taken to prevent the adulteration of orange juice and check its authenticity, that is, its declared origin and content. Producing countries, aware of the damage that adulteration can do to the legitimate trade, carry out various inspection and control procedures. Companies buying orange juice products try to purchase only through reliable suppliers known to have a good reputation. Voluntary organisations with declared self-control are established in Europe. Both suppliers and buyers are members. They are committed to carrying out self-control and following certain agreed rules. Examples of such organisations are SGF/IRMA, originating in Germany, and EQCS, European Quality Control System for juices and nectars. EQCS was founded by AIJN and its EU-based participants produce more than 85 % of all the fruit juices and nectars in the EU. The basis for testing quality and authenticity parameters by the EQCS and its European members, and SGF/IRMA for their members (raw material suppliers in more than 50 countries), is the AIJN Code of Practice. Due to intensive collaboration directed by the AIJN, local standards such as the RSK values in Germany, old AFNOR standards in France and the quality criteria in the Netherlands are incorporated in the AIJN Code of Practice. This means that the old, and sometimes still available standards, are not updated anymore and therefore no longer applied.
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11.2 The problem of adulteration
4. Isotopic fingerprinting of sugar content. Because of the high price of natural juice, the economic temptation to adulterate orange juice by adding sugar from sugar cane and sugar beet, or in the form of corn syrup, is considerable. Fortunately, isotopic technique can now tell the differences between these different sugars by analysing their carbon content.
11.2.2 TELLING WRONG FROM RIGHT
As the adulteration of orange juice has become increasingly sophisticated, the analytical methods needed to detect fraud have been developed to reveal specific types of adulteration. These analytical methods can be divided into four main groups. 1. Simple physical measurements such as weight, volume, density, acidity, purity and sample concentration. Although these measurements do little to prove the authenticity of the product, they do give an indication of the value or price of the commodity tested. 2. Comparing the analytical composition of samples with reference standards. Typical parameters include the content of sugars, organic acids, amino acids, trace elements, etc., and flavour profiles. Spectrographic adsorption patterns derived from visible light, ultraviolet light and fluorescent measurements are important for providing “fingerprints” of orange juice samples. Although useful, the main disadvantage of this method is that the pattern for authentic products varies to an unacceptable degree and can often be matched by adulterators adding appropriate “cocktails” to adulterated orange juice. 3. Testing for components that are not normally present in orange juice, or only present in trace amounts. Such components include natural or artificial flavours, D-malic or D-amino acids (as opposed to their common L-counterparts), synthetic intermediates or catalysts, preservatives like benzoates, etc. If these substances are found in amounts above accepted levels, then this is usually good proof of adulteration. Nevertheless, skilled adulterators are known to use pure or modified additives that can mislead both analysts and their instruments.
Isotope analysis
The carbon atom exists in two different isotopes, 12C, which has a natural abundance of 98.89 %, and 13C, the heavier isotope with a natural abundance of 1.11 %. During photosynthesis, plants discriminate against 13C. The degree of depletion of 13C in plant tissue as a result of this depends on how a plant extracts carbon dioxide, CO2, from the air. As the orange plant extracts its carbon in a different way from sugar cane and maize, the relative proportions of 12C and 13C in these plant tissues also differ. This fact can be used to trace the origin of sugar with the help of carbon stable isotope ratio analysis (CSIRA), and hence to determine whether juice has been adulterated by adding either cane sugar or high fructose corn syrup (HFCS).
value of juice is such that “The even modest adulteration can result in large profits
”
A trickier problem is to tell the difference between natural orange sugars and sugar from sugar beet, as both these plants extract carbon dioxide from air in exactly the same way. However, the position of the 13C atom in the sugar molecule does differ between the two sugar sources. This can be detected using SNIF-NMR analysis (Site-specific Natural Isotopic Fractionation measured by Nuclear Magnetic Resonance). Thus all three of the most commonly used sugar adulterants can now be detected.
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11.2 The problem of adulteration
190
12
Glossary
Absorption
Antioxidant
Penetration of a substance (e.g. food component) into another material (e.g. packaging material).
A compound which oxidises readily, thereby preventing or minimising oxidation of other compounds. It can occur naturally or be added to food and drinks.
Adsorption
Aroma
The binding of gases, liquids or dissolved substances by adhesion on the surfaces of solids.
An odour with a pleasant connotation. For orange juice, the word is also used for the flavour fraction called essence aroma (defined below).
Acid
Being acid means having a pH below neutral. Hence, an acid liquid is a liquid of pH<7. The opposite of alkaline on the pH spectrum. Foodstuffs of pH<4.6 are often referred to as “high-acid”.
Ascorbic acid
A vitamin found in plants, especially fruits and green vegetables. It forms white crystals when purified and dried. Also called vitamin C.
Acid content
Box
Total acidity for orange juice is expressed as grams citric acid per litre juice (Europe), or as grams citric acid per 100 g juice, % w/w (USA).
Weight unit for orange fruit used in reporting of harvest and plant intake. 1 box (field box) is defined as 90 lb (or 40.8 kg) of oranges. (A box of grapefruit equals only 85 lb of fruit.)
Acid catalysed hydrolysis
A chemical reaction promoted by an acid environment in which a complex molecule is split into two smaller molecules by the addition of water.
° Brix
Concentration of all soluble solids in juice. It is not a measure of sugars only, although sugars make up the bulk of the solids in orange juice. Brix is determined by measurement of juice density or refractive index.
Acidity
Total acid content of juice. Aerobic reaction
A reaction which requires free oxygen to take place.
Brix:acid ratio
Albedo
Carotenoids
See Ratio.
The white spongy layer of tissue found just under the coloured outer portion of the peel (flavedo). The albedo layer is rich in pectin substances and hemicellulose.
A class of yellow, orange and red pigments which occurs naturally in fruits and vegetables. The carotenoids have traditionally been classified as carotenes (pure hydrocarbons) and xanthophylls (hydrocarbons containing oxygen).
Alkaline
Being alkaline (or basic) means having a pH above neutral. Hence, an alkaline liquid is a liquid of pH>7. The opposite of acid on the pH spectrum. Anaerobic reaction
A reaction which does not require free oxygen to take place.
191
Glossary
Cells
Corrected °Brix
A commercial expression sometimes used for pulp. It is also referred to as frozen cells and frozen pulp.
°Brix value obtained after correction for the acid content of juice. It represents the actual sugar concentration of juice.
Cell sacs or whole cells
Crystallinity
Intact citrus cells which still contain juice. Whole cells cannot be obtained by conventional juice extraction methods because these, as implied, break open cells to remove the juice.
The degree of crystallinity is the amount of well-organised areas of molecules in a solid material. The higher the crystallinity, the more difficult it is for for small molecules like oxygen to penetrate.
Cloud
Cloud gives rise to the opaque appearance of orange juice. It is formed by soluble and insoluble compounds released during juice extraction. The solid particles are kept in suspension by the presence of soluble pectin in the juice. Cloud is an important quality attribute of most citrus juices and contributes to their mouthfeel.
Deaeration
The process of removing air (oxygen) from juice. Dispersed air as free air bubbles is quite easily removed from juice but dissolved air requires an effective deaeration process.
Cloud loss
Deaerator
The undesirable occurrence of orange juice separating into a clear upper phase (serum) and a bottom sediment. Cloud loss occurs when juice viscosity is reduced by a too low a concentration of soluble pectin (in turn the result of enzyme activity). Hence, insoluble compounds can no longer be maintained in suspension.
The equipment in which juice is deaerated, typically a system including a vacuum vessel. Defects
Factors that degrade citrus product quality. Examples of defects are the presence of small seeds or black specs in juice, poor colour scores and outof-range ratios.
Cold-pressed oil
Diacetyl
See cold-pressed peel oil
Diacetyl is a natural fermentation by-product of acid-forming bacteria and imparts a “buttermilk” odour if its concentration exceeds 1.0 ppm.
Cold-pressed peel oil
The oil derived from the peel of citrus fruits. Oil sacs are found in the surface of the peel and these are ruptured during oil extraction. The oil is recovered from the oil/water emulsion by mechanical means (as opposed to thermal processing). Also known simply as cold-pressed oil, peel oil or CPPO.
Diffusion
The mass transport of substances (e.g. oxygen and limonene) through material (e.g. polymer). The driving force is the difference in concentration of the substance in question on the inside and outside of a material. The substance will flow from an area of higher concentration to an area of lower concentration.
Colour score
A numerical value to rate the colour of citrus juices. In the USA it is often determined by the use of a Hunter citrus colorimeter. By comparing the red and yellow colour components of the sample to a USDA standard, a “score” can be assigned.
Diffusivity
The ability of a substance to permit diffusion. d-Limonene
The main component of oil found in oranges. d-Limonene makes up >90 % of peel oil and essence oil. It is also recovered as a by-product from waste peel. d-Limonene belongs to a group of hydrocarbon molecules called terpenes.
Core wash
The process of recovering soluble solids (mainly sugars) from the centre core of the fruit discharged separately from squeezer-type extractors. The resulting liquid product is also called core wash. See also the analogous “Pulp wash”.
192
Glossary
Endocarp
FCOJ
Another name for the edible portion of the orange fruit.
Abbreviation for Frozen Concentrated Orange Juice. It is the most common bulk orange juice product stored and shipped. FCOJ is produced commercially by concentrating juice up to 66 °Brix by evaporation.
Enzyme activity
A measure of enzyme concentration in juice. The necessary inactivation of enzymes is achieved by heat treatment of juice.
Fibres
The original definition of dietary fibres (Hipsky, 1953) is materials derived from plant cell walls in foods. It is sometimes used to mean large solid particles in juice, better described as floating pulp.
Enzymes
These are proteins which catalyse biochemical reactions. As regards orange juice quality, pectin methyl esterase (PME) is the most important enzyme in the juice as it is responsible for breaking down pectin, thereby causing cloud loss. It is found in cell walls (e.g. peel and juice sacs) and is squeezed out from the fruit and mixes with the juice during the extraction process.
Finisher
Equipment used to separate pulp from juice. This process is referred to as juice finishing. Flash pasteurisation
The expression used for pasteurisation carried out in a heat exchanger (during a very short period of time, a “flash”) as opposed to tunnel pasteurisation. There is no flash of product. Also referred to as HTST, high temperature short time heat treatment.
Essence
The volatile components recovered from the evaporation process. Essence is separated into an aqueous phase (essence aroma) and an oil phase (essence oil). Essence aroma
Flavedo
A fraction of volatile flavours recovered from the evaporation process together with essence oil (in a ratio of about 10:1). Essence aroma is clear and colourless and contains water-soluble flavour components originating from the juice. It contributes a fruity aroma and a light citrus taste to juice. Also known simply as aroma or water phase.
The coloured outer portion of peel. Carotenoids in the flavedo impart the characteristic colour of orange fruit. The flavedo also includes the oil glands which contain peel oil. Flavour
A complex combination of the sensations experienced through the senses of taste and smell, as well as the textural sensations perceived via the mouth or throat.
Essence oil
This is a clear, pale yellow oil recovered from the evaporation process. Essence oil is a source of specific flavour notes, mainly esters and carbonyls. It contributes a floral fruity aroma and a juicy flavour to juice.
Fold
The word used to express the concentration factor of flavours in a liquid. For example, in a 5fold flavour, the flavour compounds have been concentrated 5 times.
Essential oils
A general term for volatile oils, extracted from plants, fruits and flowers, having characteristic odours. Evaporation
The process of removing water from juice by heat. Extraction
Extraction related to oranges is the process of squeezing out juice from either whole or halved oranges by means of mechanical pressure. Peel oil is also obtained by a mechanical extraction process. 193
Glossary
Gelation
Limonin
The tendency of concentrate to become lumpy and difficult to reconstitute is known as gelation. It results from enzyme activity caused typically by insufficient pasteurisation prior to juice concentration, or from incorrect storage temperature.
A complex compound that causes bitterness in juice. It is formed in orange juice shortly after extraction. In most juices, the limonin concentration is very low and does not cause a problem except for juice made from Shamouti and Navel (seedless) oranges. Maillard reaction
Hesperidin
A flavonoid found in citrus juices. As it is highly insoluble, it precipitates during juice concentration and accumulates on surfaces in evaporators and extractors. Although it imparts no off-flavour to juice, it may appear as white specks and be considered a defect.
A non-enzymatic chemical reaction involving condensation of an amino group and a reducing group (sugars), resulting in the formation of intermediates which ultimately polymerise to form brown pigments (melanoidins).
Hot filling
A group of orange fruit, Citrus reticulata. This group includes tangerine varieties.
Mandarins
The filling procedure whereby the high temperature of the product being filled is used to “sterilise” the food-contact surface of the packaging material.
Mesh
The unit used for screen sizing. Mesh is the number of equal openings per linear inch. A 20 mesh screen therefore has much larger openings than a 60 mesh screen.
Hydrogen peroxide
A chemical with the formula H2O2. It is a clear liquid with strong oxidative power and is produced as aqueous solutions of 35-90 % w/w hydrogen peroxide concentration. It is used as a sterilisation agent in filling machines.
Naringin
A bitterness substance (flavonoid) mainly found in grapefruit juices.
Hydrometer
NFC
An instrument placed in a liquid for measuring its relative density or °Brix. It comprises a sealed graduated tube with a weighted bulb at the lower end.
Abbreviation for not-from-concentrate juice. Juice of natural (single) strength which has neither undergone concentration nor dilution during production.
Inert gas
Oil content
A chemically inactive gas (for example nitrogen).
The oil content of orange juice is often equated to the concentration of d-limonene, since it makes up 90 % or more of peel oil and essence oil. d-Limonene can be measured by a relatively simple titration method, the Scott method. Oil content, also referred to as Scott oil, is expressed as % v/v in single-strength juice.
Juice vesicles
Another name for the juice-containing sacs in orange fruit.
Organoleptic
Relating to a property of food that can be perceived by the sense organs.
194
Glossary
POJ
Pounds solids per box
Abbreviation for pasteurised orange juice. It is a term used in Florida for NFC juice.
A measure in weight of the total dissolved solids in a given box of fruit. Used in Florida as basis for payment of fruit. It is calculated by multiplying the amount of juice per box (by the State Test) with the Brix level of the juice.
Pectin
A type of polysaccharide found mainly in the albedo but also in other parts of the fruit. It is a naturally occurring colloidal stabiliser that gives juice its “body” or viscosity.
Press liquor
Peel oil
A product stream in the feed mill area obtained by removing moisture from the citrus peel in a (screw) press. The press liquor is concentrated in a waste heat evaporator to form molasses.
See cold-pressed peel oil.
Pulp
Permeability
The solid particles in orange juice. Also the commercial name for the product, consisting of broken pieces of cell sacs and segment wall, added back to the final juice. There are several terms related to pulp in juice, of which some are: Floating pulp – larger solid particles in juice consisting of pieces of ruptured cell sacs and segment walls. Most float to the top after juice is stirred. Sinking pulp – very small solid particles (<0.5mm) which are suspended in the juice and settle from the juice with time or spin down in a centrifuge. Typical values range from 5 to 12 v/v centrifuged pulp. Suspended pulp, bottom pulp and centrifuged pulp are sometimes used instead of sinking pulp.
It is a measure of a material’s ability to be penetrated, particularly by gases. The permeability value is obtained by multiplying diffusivity and solubility. Phytosanitary
Measures taken with plants to protect human, animal and plant health. Polar (and nonpolar)
A polar molecule, e.g. water, has both positively and negatively charged regions. Two polar molecules intermix as they are attracted by each other’s dipole forces. A nonpolar molecule, e.g. oil, has no areas of positive and negative charge within it. Generally, nonpolar molecules do not intermix well with polar ones. Polymer
A large molecule which is obtained by polymerisation of many smaller identical molecules (monomers). In this document, polymer is used synonymously with plastic.
For pulp as a product: Aseptic pulp – pulp product stored in aseptic bag-in-drums. Frozen pulp – pulp product sold in frozen form.
Polyolefines
Pulp wash
Polymers prepared by polymerisation of α-olefins. Examples of polyolefines are polyethylene and polypropylene.
The process by which soluble solids (mainly sugars) are recovered from pulp. The soluble solids are leached from the pulp with water through a system of mixing screws and finishers. The liquid stream from a pulp wash system is referred to as pulp wash, secondary solids, or WESOS (Water Extracted Soluble Orange Solids).
Plate count
A method of determining the number of microorganisms in food. It is often expressed as colonyforming units per millilitre sample (CFU/ml). Pounds juice per box
The actual weight of juice extracted from a 90 lb. box of orange fruit as measured by the State Test extractor (Florida).
195
Glossary
Soluble solids are solid materials that will dissolve in the liquid in question. Sugars and acids in citrus juices are commonly referred to as soluble solids.
Quick Fibre
A test method to determine the relative dryness of pulp. It indicates how hard the squeezing of pulp to remove juice in the finishers has been. Quick Fibre (QF) is also a measure of how wet the pulp is as it exits the final, or drying, finisher in the pulp production line.
Specific gravity
Refers to the actual weight of a liquid in relation to water (at defined temperatures). Also called relative density. State Test
Ratio
Standardised method used in Florida to establish the potential juice yield from a delivered load of fruit. Juice extraction is carried out using a State test extractor under well-defined operating conditions. The actual juice yield during commercial processing of the same fruit batch is different to, and often higher than, the State Test yield.
The ratio is obtained by dividing the °Brix of a juice product by the acid content (as % wt). The ratio, also referred to as Brix:acid ratio, is important for describing taste as a measure of the balance between the sweet and sour sensations. Consumers prefer a ratio of around 15:1.
Sweet oranges
Recontamination
For orange juice, the sweet orange, Citrus sinensis, is the most important group of orange fruit. Regulations in the EU stipulate that orange juice may only be made from the sweet orange, whereas in other markets legislation allows the addition of small amounts of juice from other orange varieties, like mandarins, to balance juice taste.
Contamination of juice with microorganisms after it has been pasteurised. Also known as reinfection. Refractive index
A measure of how much light is refracted, that is, changes direction, on passing from one medium to another. The refractive index for a solution depends on its concentration. The measured refractive index can be translated into concentration of soluble solids of a solution such as orange juice.
Taste
Sensations perceived via the taste buds of the tongue when stimulated by certain substances.
Refractometer
An instrument for measuring refractive index. Sensory analysis
Viscosity
Examination of a product by the sense organs.
Viscosity is a measure of the “thickness” of a fluid. It affects the “body” of the juice created primarily by pectin-related stabilisation of the cloud or colloids in the juice. The presence of insoluble material also contributes to increased juice body or viscosity.
Shelf life
The time period up to the point when a food product becomes unacceptable from a safety, sensorial or nutritional perspective. Single-strength
The term assigned to juice at its natural strength, either directly from the extraction process or in a reconstituted form.
Washed pulp
The solid particles remaining from the pulp wash process. It is sold in frozen form for addition to fruit beverages, or recovered in the feed mill area for use as animal feed.
Solids
Insoluble solids are, simply put, solids that will not dissolve in the liquid in question. In orange juice they consist mainly of cellulosic and insoluble pectic substances generally associated with pulp.
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13
Abbreviations, weights and measures
13.1 Abbreviations The definitions of some abbreviations used in the orange juice industry and in The Orange Book are given below. Scientific expressions and products for which abbreviated names are used are given in the Glossary (Section 12). Trade expressions:
Units of measurement :
cif DPC DPP fca fot fob RTD RTS SSE
°Bx °C cP °F fl oz ft gal gpm g h kPa l lb meq µm m min mm m2 m3 mg mph oz ppm s t % v/v % w/w
cost, insurance and freight direct product cost direct product profit free carrier free on truck free on board ready to drink ready to serve single strength equivalent
Materials and packaging manufacture:
EVOH ethylene vinyl alcohol PA polyamide PE polyethylene HDPE high density polyethylene LDPE low density polyethylene LLDPE linear low density polyethylene PEN polyethylene naphtalate PET polyethylene terephtalate PP polypropylene EBM extrusion blow-moulding SBM stretch blow-moulding Organisations:
AIJN
Association of the Industry of Juices and Nectars from Fruits and Vegetables of the European Union FAO Food and Agricultural Organisation (United Nations) FDA Food and Drug Administration (USA) IFU International Federation of Fruit Juice Producers IFT Institute of Food Technologists (USA) JPA Juice Products Association USDA United States Department of Agriculture WHO World Health Organisation (United Nations)
degree Brix degree Celsius centipoise (viscosity) degree Fahrenheit fluid ounce feet gallon* gallons per minute gram hour kiloPascal litre pound (weight) milliequivalent micrometre (0.000 001 metre) metre minute millimetre square metre cubic metre milligram miles per hour ounce parts per million (e.g. mg/kg) second tonne % volume by volume % weight by weight
* Gallon means US gallon (128 fl oz or 0.83 Imperial gallon) in The Orange Book.
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13.2 Unit conversions
13.2 Unit conversions In the orange juice industry several different systems are used around the world for units of measurement. The list below shows how you can convert between some of these units.
To convert boxes boxes ounces pounds (lb) short tons tons (metric) long tons
into kg lb kg kg kg kg kg
multiply by 40.8 90 0.02835 0.454 907.8 1 000 1 016
fluid ounces (US) pints (US) quarts (US) gallons (US) fluid ounces (Imperial) pints (Imperial) quarts (Imperial) gallons (Imperial) cubic feet cubic metres
litres litres litres litres litres litres litres litres litres litres
0.02957 0.4732 0.9463 3.785 0.02841 0.5683 1.136 4.546 28.32 1000
gallons/min (gpm)
0.2271
inches feet yards miles
cubic metres/hour (m3/hr) metres metres metres metres
square feet acres
square metres (m2) square metres (m2)
0.09290 4 047.0
miles/hr (mph)
kilometres/hr
1.609
bar kg/cm2 (at) atm (normal atmosphere) pounds/square inch (psi)
kPa kPa kPa kPa
100.0 98.1 101.3 6.895
Btu (British thermal units) kilocalories (kcal)
kilowatt hour (kWh) kilowatt hour (kWh)
0.0002928 0.001163
horsepower (UK, USA)
kilowatts (kW)
0.7457
°Fahrenheit
°Celsius
(°F x 5/9) - 32
Relationship for liquid volumes: US: 1 gallon = 4 quarts = 8 pints = 128 fluid ounces Imperial: 1 gallon = 4 quarts = 8 pints = 160 fluid ounces
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0.02540 0.3048 0.9144 1 609.0
13.3 Density tables for sugar solutions
13.3 Density tables for sugar solutions
BRIX LEVELS FOR SINGLE-STRENGTH JUICES
The official table for true density values of sucrose solutions (at 20 °C) was published by Plato in 1900 and is still universally used today. Relative densities and weight of solids of sucrose solutions were derived from the Plato table (1942). These values were adopted as an official table for determining solids weights in orange juice concentrates by the Florida citrus industry. Later the tables were further developed and computerised. They are used throughout the citrus industry to provide a uniform reference for determining the quantity of soluble solids (“pounds solids”) in fruit juices and concentrates. An abstract from the sugar density tables developed by Chen (1989) is given below. The full table includes true density in vacuum, density in air, etc. The values in the list below can be used to approximately relate the soluble solids (or sugar) content of orange juice to its specific gravity, for example when calculating the blending formula for reconstituting juice. (See subsection 7.4) Orange juice is not a pure sugar solution but contains other solids, both dissolved and insoluble. Explanations to the table below:
Conc. in °Brix or %w = sucrose concentration as %weight Conc. in g/l = sucrose concentration as grams sucrose per litre solution at 20 °C Relative density 20/20 = density of sucrose solution at 20 °C relative to the density of water at 20 °C. Also referred to as specific gravity 20/20.
Conc. in °Brix or % w 8.5 8.6 8.7 8.8 8.9
Conc. in g/l
Relative density 20°/20 °C 1.03385 1.03426 1.03467 1.03508 1.03549
87.63 88.69 89.76 90.83 91.90
9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9
92.97 94.04 95.11 96.18 97.25 98.33 99.40 100.48 101.55 102.63
1.03590 1.03631 1.03672 1.03714 1.03755 1.03796 1.03838 1.03879 1.03920 1.03962
10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9
103.71 104.79 105.87 106.95 108.03 109.11 110.19 111.28 112.36 113.45
1.04003 1.04044 1.04086 1.04127 1.04169 1.04210 1.04252 1.04294 1.04335 1.04377
11.0 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9
114.54 115.62 116.71 117.80 118.89 119.98 121.07 122.17 123.26 124.35
1.04419 1.04460 1.04502 1.04544 1.04586 1.04628 1.04670 1.04712 1.04754 1.04795
12.0 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9
125.45 126.55 127.64 128.74 129.84 130.94 132.04 133.14 134.24 135.35
1.04837 1.04880 1.04922 1.04964 1.05006 1.05048 1.05090 1.05132 1.05175 1.05217
13.0 13.1 13.2 13.4 13.5
136.45 137.56 138.66 140.88 141.98
1.05259 1.05302 1.05344 1.05429 1.05471
Source: Fruit Juice Processing Technology, edited by S. Nagy, C.S Chen and P. Shaw.
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13.3 Density tables for sugar solutions
BRIX LEVELS FOR CONCENTRATES Conc. in °Brix or % w 40.0 40.5 41.0 41.5 42.0 42.5 43.0 43.5 44.0 44.5 45.0 45.5 46.0 46.5 47.0 47.5 48.0 48.5 49.0 49.5 50.0 50.5 51.0 51.5 52.0 52.5 53.0 53.5 54.0 54.5 55.0 55.5 56.0 56.5 57.0 57.5 58.0 58.5 59.0 59.5
Conc. in g/l 470.17 475.70 484.03 491.01 498.01 505.05 512.11 519.21 526.34 533.49 540.68 547.90 555.15 562.43 569.74 577.08 584.46 591.86 599.30 606.77 614.27 621.80 629.37 636.97 644.60 652.26 659.96 667.69 675.45 683.25 691.08 698.95 706.84 714.77 722.74 730.74 738.78 746.84 754.95 763.09
Relative density 20°/20 °C 1.17875 1.18130 1.18391 1.18650 1.18911 1.19172 1.19434 1.19359 1.19622 1.19886 1.20492 1.20759 1.21026 1.20952 1.21565 1.21835 1.21762 1.22379 1.22653 1.22927 1.23202 1.23478 1.23756 1.24934 1.24313 1.24593 1.24874 1.25156 1.25084 1.25722 1.26007 1.26293 1.26580 1.26867 1.27156 1.27446 1.27736 1.28028 1.28320 1.28614
Conc. in °Brix or % w 60.0 60.5 61.0 61.5 62.0 62.5 63.0 63.5 64.0 64.5 65.0 65.5 66.0 66.5 67.0 67.5 68.0 68.5 69.0 69.5 70.0
Source: Fruit Juice Processing Technology, edited by S. Nagy, C.S Chen and P. Shaw.
200
Conc. in g/l 771.26 779.47 787.71 795.99 804.31 812.66 821.05 829.47 837.93 846.43 854.96 863.53 872.13 880.77 889.45 898.17 906.92 915.71 924.54 933.41 942.31
Relative density 20°/20 °C 1.28908 1.29203 1.29500 1.29797 1.30095 1.30394 1.30694 1.30996 1.31298 1.31601 1.31905 1.32210 1.32516 1.32823 1.33130 1.33439 1.33749 1.34060 1.34372 1.34684 1.34998
14
Further reading and references
14.1 Books on orange juice
Quality Control Manual for Citrus Processing Plants
Below is a list of books containing detailed information about orange juice, both as a product and its processing. Some of these books have been referred to in The Orange Book as sources of information.
Vol. II, revised and enlarged 1992. 349 pp. Editors: J. Redd, D. Hendrix and C. Hendrix Jr. Publisher: AgScience Inc., Florida. 3 sections covering plant operations, citrus blending techniques, and formulating and citrus mathematics. It contains practical information about the everyday operation and management of citrus processing plants.
Production and Packaging of Non-carbonated Fruit Juices and Fruit Beverages
2nd edition, 1995, 423 pp. Editor: P.R. Ashurst, Publisher: Blackie Academic & Professional, UK. 15 sections including general descriptions of processing of common juices such as citrus, apple, grape juice and tropical fruits. Also sections on nutritional value, fruit juice legislation and authenticity control for orange juice. Individual contributors to respective sections come from the juice and supplier industry.
Quality Control Manual for Citrus Processing Plants
Vol. III, 1996, 325 pp. Editors: J. Redd, P. Shaw, C. Hendrix Jr. and D. Hendrix. Publisher: AgScience Inc., Florida. A comprehensive review of state-of-the-art knowledge on respective topics. Sections cover: flavours, speciality and by-products; raw product as applied to processing; processing parameters. The editors of this series of books have long experience in the Florida citrus industry, particularly with flavours and by-products.
Fruit Juice Processing Technology
1993, 713 pp. Editors: S. Nagy, C.S. Chen and P. Shaw. Publisher: AgScience Inc, Florida. 16 sections covering fruit processing of citrus fruits and several tropical fruits, berries and apples (total 22 types of fruit). It gives an overview of how the various fruits are processed and what equipment can be used.
Handbook of Citrus By-Products and Processing Technology.
1999, 247 pp. Author: R. J. Braddock Publisher: John Wiley & Sons, Inc., NY. 17 chapters detailing citrus juice and by-products manufacture. Included are details of juice and thermal processing including concentrate, NFC, enzyme inactivation kinetics, the properties and manufacture of citrus essential oils, dlimonene chemistry and properties, dried pulp and descriptions of other citrus by-products.
Quality Control Manual for Citrus Processing Plants
Vol. I, revised 1986, 250 pp. Editors: J. Redd, D. Hendrix and C. Hendrix Jr. Publisher: AgScience Inc., Florida. 9 sections covering regulations, analytical methods, microbiology and conversion charts. It is intended for plant technologists and others involved with analyses and understanding plant operating procedures. The first of 3 books compiling and presenting comprehensive information about citrus processing.
Citrus Processing: Quality Control and Technology
1991, 473 pp. Author: Dan A. Kimball. Publisher: AVI Book of Van Nostrand Reinhold. A comprehensive book describing in detail citrus juice properties and processing technology from an analytical and quality control point of view. Analytical methods are included. Enlarged 2nd edition published in 1999.
201
14.1 Books on orange juice
Technical Manual - Reconstituted Florida Orange Juice
Chen, Chin Shu
“Mathematical correlations for calculation of Brix-apparent density of sucrose solutions.” Lebensmittel.-Wissenschaft.Technol, 1989 (22); 154-156.
and
Technical Manual - Freshly Squeezed Florida Orange Juice
1985 Publisher: Florida Department of Citrus, Scientific Research Department, University of Florida -IFAS-CREC. Includes instructions, regulations and analytical procedures for production, packaging and distribution of respective products. These manuals are specific to Florida.
Dürr, P., Schobinger, U., and Waldvogel, R.
“Aroma quality of orange juice after filling and storage in soft packages and glass bottles.” Alimenta, 1981 (20); 91-93. Goodrich, R.M. and Brown, M.G.
”European Markets for NFC: Supply and Demand Issues.” Presented at the 7th International Economic Outlook Conference for Citrus and Non-Citrus Juices, Orlando, Florida, 2000.
Other books on citrus fruit An Illustrated Guide to Citrus Varieties of the World
Johnson, J.D. and Vora, J.D.
“Natural citrus essence: production and application.” Presented at the 43rd Annual Meeting of International Food Technologists, New Orleans, Louisiana, 1983.
2nd edition, 2000, 160 pp. Author: J. Saunt. Publisher: Sinclair International Ltd, UK. Descriptions and colour illustrations of orange and other citrus varieties.
Kanner, J., Fishbein, J., Shalom, P., Harel, S., and Ben-Gera, I.
Compendium on Citrus Diseases
“Storage stability of orange juice concentrate packaged aseptically.” Journal of Food Science, 1982 ( 47); 429.
2nd edition, 2000, 128pp. Editors: L.W. Timmer, S.M. Garnesey, J.H. Graham. Publisher: APS American Phytopathological Society Press, Minnesota. Descriptions of citrus diseases and classification of pathogens. Colour pictures for disease diagnosis.
Mannheim, Chaim and Havkin, Margalit.
“Shelf life of aseptically bottled orange juice.” Journal of Food Processing and Preservation, 1981 (5); 1-6. Nonino, Eliseu A.
“Orange juice quality upgrading.” Fruit Processing, 1995; issue no. 11, 372-374.
14.2 References
Pieper, Gabrielle; Borgudd, Lars; Ackermann, Paul and Fellers, Paul.
Below follows a list of publications to which reference is made in various sections of The Orange Book.
“Absorption of aroma volatiles of orange juice into laminated carton packages did not affect sensory quality.” Journal of Food Science, 1992 (57), issue no. 6, 1408-1411.
Articles and scientific papers Ackermann, P.W. and Wartenberg, E.W.
“Shelf life of citrus juices. A comparison between packages.” International Federation of Fruit Juice Producers, Scientific Technical Commission XIX, Symposium The Hague, 1986; 143-160.
Redd, J.B.
Braddock, R.J. and Sadler, G.D.
Shapton, D.A., Lovelock, D.W. and Laurita-Longo, R.
“Distillation Systems.” Presented at the Annual short course for the food industry, International Food Technologists, University of Florida, Gainsville, Florida, 1976.
“Chemical changes in citrus juice during concentration processes.” American Chemical Society Symposium Series, 1989 (405); chapter 22.
“The evaluation of sterilisation and pasteurisation processes from temperature measurements in degrees Celsius.” Journal of Applied Bacteriology, 1971 (34); issue no. 2, 491-500.
202
14.1 Books on orange juice
Other published and unpublished material Internet links valid August 2004
USDA Foreign Agricultural Services -GAIN reports 2003. Citrus annual reports for various countries. USDA FAS: Washington D.C., USA.
Citrus fruit, fresh and processed: Annual statistics 2002. FAO: Rome, Italy.
Accessible at www.fas.usda.gov
Accessible at www.fao.org/es/ESC
Vattenbenbehandlingsmetoder. (Water treatment methods.) Vattenteknik AB: Malmö, Sweden, 1992.
Citrus Reference Book 2004. Florida Department of Citrus: Lakeland, Florida.
Publications on fruit juice regulations
www.fred.ifas.ufl.edu/citrus/pubs/index.htm
Australian New Zealand Food Standards Code -Standard 2.6.1, 2000. Valid for Fruit Juice and Vegetable Juice. FSANZ Food Standards Australia New Zealand: Canberra, Australia.
Code of Practice: Reference Guideline for Orange Juice, 2003. AIJN: Brussels, Belgium.
www.foodstandards.gov.au/_srcfiles/Standard261_ Juice_v62.pdf
Compass Market Statistics. Internal publication. Tetra Pak: Lund, Sweden, 2002.
Codex Alimentarius - Codex Standard 45, 1981. Covers orange juice preserved exclusively by physical means. Codex Alimentarius Commission/FAO: Rome, Italy.
Dairy Processing Handbook. Tetra Pak: Lund, Sweden, 2003. Fruit Beverages in the US, 2000. Beverage Marketing Corp.: New York, USA.
ftp.fao.org/codex/standard/en/CXS_045e.pdf
or via
www.codexalimentarius.net/web/standard_ list.do?lang=en
Fruit/Vegetable Juice Country Reports 2004. Euromonitor: London, UK.
European regulation for fruit juice - Council Directive 2001/112/EC, 2001. Covers fruit juices and certain similar products intended for human consumption. Council of the European Union: Brussels, Belgium.
Givaudan Roure, Florida, USA. Personal communication. Livsmedelstabell Energi och Näringsämnen. Statens Livsmedelsverk: Uppsala, Sweden.
http://europa.eu.int/eur-lex/pri/en/oj/dat/2002/l_010/ l_01020020112en00580066.pdf
Redd, J.B. and Praschan V. Quality Control Manual for Citrus Processing Plants. AgScience Inc.: Auburndale, Florida, 1975.
United States Standards for Grades of Orange Juice, 1983. USDA, Agricultural Marketing Services: Washington DC, USA.
Robertson, Gordon L. Food Packaging: Principles and Practice. Marcel Dekker Inc.: New York, USA, 1993.
www.ams.usda.gov/standards/cnorange.pdf
Juice HAACP Hazard and Controls Guidance, 2004. US FDA, Center for Food Safety & Applied Nutrition: College Park, MD, USA.
Soft Drinks Report 2003. Canadean: London, UK.
www.cfsan.fda.gov/~dms/juicgu10.html
Technical Vademecum: Beverage manual. Döhler-Eurocitrus: Darmstadt, Germany, 1999.
203
14.3 Useful websites
14.3 Useful websites
UNCTAD* Info Comm - Market information in the commodities area - Citrus Fruit Overview of production, manufacturing and trade.
Internet links valid August 2004
Below is a list of useful websites covering the orange juice industry.
*United Nations Conference On Trade And Development
http://r0.unctad.org/infocomm/anglais/orange/ market.htm
ABECITRUS -The Brazilian Association of Citrus Exporters. Presentation of Brazil orange juice industry incl. research studies and export statistics.
FAO - Food and Agriculture Organization of the UN Statistics on fruit crop, processing and utilisation.
www.abecitrus.com.br
CREC- Citrus Research and Education Center at University of Florida. Website includes information about citrus training courses, events and research publications.
www.fao.org/es/ESC
Codex Alimentarius Commission Joint FAO/WHO food standards programme.
www.lal.ufl.edu
www.codexalimentarius.net
Citrus Flavour and Colour Very informative website published by the flavour research team at CREC.
AIJN - Association of the Industry of Juices and Nectars From Fruits and Vegetables of the European Union.
www.crec.ifas.ufl.edu/rouseff/
www.aijn.org
FDOC - Florida Department of Citrus Website for and about the Florida citrus industry including commercial and regulatory news.
IFU - The International Federation of Fruit Juice Producers www.ifu-fruitjuice.com
www.floridajuice.com
JPA - Juice Products Association www.juiceproducts.org
FDOC - Florida Department of Citrus Economic and Market Research Comprehensive website incl. production and market data on citrus in various databases and publications.
TCJJP - Technical Committee for Juice and Juice Products www.tcjjp.org
www.fred.ifas.ufl.edu/citrus
Ultimate Citrus - The Ultimate Citrus Page A comprehensive list of websites covering the citrus industry. www.ultimatecitrus.com
204
Index Topic
Acetaldehydes Acidity Acids Acid-tolerant bacteria Activated carbon filtration Adulteration Ad Valorem tariffs AIJN quality requirements Air – see Oxygen Albedo Alcohols – basic structure – in flavour fractions Aldehydes – basic structure – in flavour fractions Australia Aroma compounds – basic structure Ascorbic acid – see vitamin C Aseptic buffer Aseptic storage In tanks In bag-in-box containers Aseptic transfer of NFC juice
Bacteria Bag-in-box bulk containers Barrier properties of packaging Bitterness Blending houses Blending systems Batch blending In-line blending Bottles – as packaging Brazil Fruit processors Orange production Orange varieties grown Growers Harvesting Shipping FCOJ to Europe Break bulk Brix Brix corrections Browning Bulk juice products Frozen storage Impact of long-term storage Shipping costs Transport and handling Bulk processors
Page
Topic
138-140 21 21 54 115 188 39 19, 186
Categories of orange juice Clarification Cloud Cloud loss California Caribbean Carton-based packages Central America Centrifugal clarification Centrifuges China Chlorination of water Citrus aurantium Citrus molasses Citrus reticulata Citrus sinensis Cleaning-in-place (CIP) Colour Colour measurement Colour changes in packaged juice Comminuted citrus base Composition of orange juice Concentrated orange juice Categories Impact of long-term storage Storage at the juice processor Storage at the juice packer Consumption of orange juice By categories Consumer preference Worldwide
6,7 157 139, 140 157 139,140 14, 186 157 128 77 112 130
54 78, 112 152, 156 25 35, 102
Page
28 72 22, 60 60 13 13 161, 162 13 73 73, 75, 84, 85 3, 4, 14 115 3 9 3 3 108, 131 25, 154 25 154 8 27 28 49 83 110, 111 174, 175 176-178 40, 42, 43
106, 119 107, 120 161, 163-165 Deaeration 76, 116, 122, 125 Deaerators 52, 54, 125 Dealkalisation of water 114 Debittering 92 Defect removal from pulp 89 Density measurement 20, 21 Deoiler oils 138 Depot – retailer´s 170 Diacetyl 54 Direct product profitability (DPP) 173 Diseases - orange crop 4 Distillation for concentrating flavours 141 Distilled oils 138 Distribution of packaged products 169 Distribution units 171 Drum emptying of concentrate 111
34 3-5, 10-16 12 33 10, 11 96 96 20, 21 20 26, 154 76 49 100 93 34, 35
205
Index
Topic
Endocarp Enzymes Essence aroma Major components Related to flavour Essence oil Major components Related to flavour Essence recovery Esters – basic structure – in flavour fractions Ethyl butyrate Evaporator systems Centrifugal Plate Tubular Export of FCOJ Extractor types
Page
Topic
Fruit reception Fruit sizer Futures market
7 59, 60 138 24, 137, 138
Glass bottles Grade A (Florida) Grading of orange fruit
138 24, 137, 139 82, 92 157 138, 139 138
Harvesting seasons Heat exchangers Plate Tubular Henry’s law Hermetic centrifuges Hesperidin flavonoid Homogenisation as part of evaporation Hot filling Hybrid oranges Hydrocarbons – basic structure – in flavour fractions Hydrocyclone
82 80 79 10 68
Feed mill operations 86 Finishers 73, 89, 91 Flavedo 6,7 Flavonoids 27 Flavour Changes in flavour during processing 48 Quality parameters 23 Standardisation 140 Volatile 136 Flavour scalping 158, 159 Flavour systems 142 Flocculation for water treatment 114 Florida Fruit processors 34, 35 Orange production 4, 6, 12 Orange varieties grown 12 Growers 33 Harvesting 4, 12 Folding of oils 140 Folic acid 27 Fortified orange juices 29 Freeze concentration 83 Frozen Concentrated Orange Juice (FCOJ) Bulk shipping 95 Commodity trading and futures market 38 Commodity trading, units 38 Definition 5 Microflora 57 Terminals for receiving products 100 Types 29 Fruit growers 33 Fruit processor – types of 34 Fruit processing – overview 64
Import duties with typical examples Import of orange juice Industry structure Iron removal from water Isotope analysis
Japan Juice extraction Juice packers Overview Process lines Juice sac Juice vesicle
Korea - Republic of
Lactic acid bacteria Laminated carton material Light refraction measurement
206
Page
65 68 38
161, 163-165 19, 184 67
4, 5 80, 123 79, 123 53 75, 85 27 81 129, 165 3 157 138 89
41 39 32 114 189
14, 41 68 36, 104, 105 105-109 6, 7 6, 7
41
54 161, 162 20
Index
Topic
Page
Topic
Light – impact on packaged juice 156 d-Limonene 24, 25, 138, 139, 156, 157 Limonin 92
Maillard reaction Major orange-growing regions Mandarin orange Manganese removal from water Marketing processors Mediterranean Membrane filtration Mexico Microflora of different products Microorganisms in orange juice Moulds
Nanofiltration of water Nectars Not-from-concentrate (NFC) Aseptic transfer Bulk shipping Definition Frozen storage Impact of long-term storage Microflora Production Reprocessing Types
Off-flavours Off-colours Oil content Oil content measurement Orange crop diseases Oil extraction Oil reduction Orange fruit Growers Products Primary Secondary (by-products) Structure Orange juice categories Orange juice consumer Orange juice consumption Orange juice quality Orange nectar Orange varieties Orifice tube Origin of orange fruit
Oxygen Effect on products Problems caused by oxygen Removal from liquids Sources Solubility Ozone treatment of water
154 3 3 114 34, 35 4, 15 83 13 57 54 56
Page
50, 152, 154 52 53 51 51 115
Packages Bottles 163 Carton-based 161, 162 Properties of 157 Types 160 Packaging Quality parameters 151 Secondary 171 Tertiary 172 Types of system 160 Pasteurisation At the juice packer 124 Primary 59, 61, 76 Purpose 59 Secondary 59, 61 Related to deaeration 122 System control 126 Time-temperature conditions for PME 60 Pasteurisation units 126 Pathogenic microorganisms 56 Pectin 9, 22, 49, 60 Pectin methyl esterase (PME) 59-61 Peel oil Concentration 84 Major components 138-140 Polishing 85 Recovery 84 Related to flavour 23, 137-139 Winterisation 85 Pigging (as part of CIP) 133 Plastic bottles 163, 164 Plato 199 Polymers – properties of 157 Press liquor 86, 87 Pricing of bulk juice products 37 Processing – impact on juice quality 46 Processing plant – overview 64 Pulp Floating pulp 7, 23, 142 Production 86 Quality 144 Terminology 143 Sinking pulp 7, 22 Pulp wash production 92 Pulpy juice 68, 143 PVG 49, 155
115 29, 108, 116, 179 130 97 5 76 49 57 74 78 28
48, 49, 155, 157 26, 154 24, 144 24 4 71 75 33 8, 9 8 8, 9 6, 7 28 174 42, 43 18 29 10-12, 25 70 2
207
Index
Topic
Quality control Quality of orange juice Quick Fibre
Ratio Reamer-type extractor Ready-to-drink (RTD) orange juice Reclaim product Refractometer Regulations Australia and New Zealand European Union Far East Juice quality Latin America Middle East USA and Canada Retailers – handling and distributing products Reverse osmosis Rework product Rotary press extractors
Page
Topic
110, 134 18, 19 145
Tangerine varieties Terminals for FCOJ Terminals for NFC Terpenes Thawing of solid frozen product Thermal processing Trade tariff terms Trading Turbofilters
21 71 28 112 21, 121 186 30, 184 187 30 186 187 30, 183
UV treatment of water
Page
3 100 101 139-141 111 61 39 38 74
115
4-vinyl guaiacol (PVG) 49, 155 Vitamin C Content in orange and some other fruits 26 Degradation in packaged juice 152, 153 Impact of oxygen on vitamin C degradation 48 Volatile flavours 24, 136, 156
169, 170 115 112 69
Water Deaeration For processing Hardness Quality at the juice packer Treatment at the juice packer Winterisation of peel oil World citrus/orange production
Sand filtration of water 114 Shipping costs 100 Shipping FCOJ 95, 96 Shipping NFC 97-99 Squeezer-type extractor 69 Soft-drink producers 37 Solvent extraction for concentrating flavours 141 South Africa 16 Spectrophotometry 22, 25 Spore-forming microorganisms 56 Stabilisation 90 Standards Juice composition and labelling 182 Codex Alimentarius 187 State Test extractor 34 Storage Concentrate at juice packer 110, 111 Fruit 67 Pulp 91 Still fruit drinks 108, 116, 179 Strainer tube 70 Sugars 20 Suspended solids measurement 22
Yeasts Yield of juice from an orange
208
116 47 113 112, 113 113 85 2-5, 10-16
55 8
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