OBJECTIVE
To study the effect of ingredients added to jam To compare the effect e ffect of additional of citric acid between jams.
INTRODUCTION
Jam, jelly and marmalade are in a group of food product produced from fruits fruits and the t he making of them are straightforward and do es not require lots of equipment or time. Although they are same in that aspect, but all of them has their o wn specific characteristic to differentiate themselves from each others. Jam is always made from whole or cut fruits, cooked to a pulp with sugar, producing a thick, fruity, spread. Jelly is made using only the juice o f the fruit and sugar. It should be clear and sparkling when whe n finished. Marmalade is similar to jam but made only from bitter Seville oranges from Spain or Portugal. Po rtugal. However for the Food preservation practical class we were given a chance to experience the making of pineapple jam. There are four main ingredients needed in the right amount to produce pro duce a successful fruit jam. They are fruit extract, sugar, sufficient sufficient pectin and acid. The combination of them will ensure the good gel formation, which act as the most important quality characteristic of a good jam. The pineapple itself contains some amount of sugar, pectin and acids. However for ripe or just ripe fruit content is not the same. Since S ince it is not sufficient sugar, pectin and acids, we had to add it during the processing. pro cessing. During this study, investigation of the effect of addition of ingredients balancing on the quality characteristics of the pineapple jam can be done.
MATERIALS
Peel, cut and blended ripe pineapple to produce a fine and homogenous puree.
METHOD R efer efer
to laboratory manual provided.
FORMULATION FOR
JAMS MAKING
Table 1: the composition of ingredients in each formulation
A Unripe 550g 550g 7g 200g 22.55ml
Fruit ripeness Fruit puree Sugar Pectin Water Citric acid(50w/v%)
B Unripe 550g 550g 7g 200g -
C ipe R ipe 550g 550g 7g 200g
D ipe R ipe 550g 550g 7g 200g -
RESULT Water activity
Table 2 : The result of water activity analysis A1 Water activity o
Temperature ( C)
A3
A4
1
2
1
2
1
2
1
2
0.714
0.722 0. 722
0.738
0.732 0. 732
0.738
0.736
0.744
0.745
24.8
25.5
25.8
25.5
24.8 24. 8
24.7
25.0
24.8
o
average
A2
0.718 at 25.15 C
o
0.735 at 25.65 C
o
0.737 at 24.75 C
o
0.745 at 24.90 C
Spread ability measurement
Table 3: The result of texture analysis Sample Gradient D1 (mm/g)
A1 1 34.259
A2 1 -9.45
2 -7.262
1 38.729
2 41.605
1 7.837
2 5.945
5.895
-7.261
35.124
37.090
7.486
5.945
The jam is too soft make the crystal analyzer touch the bottom of the bottle
0.120
0.151
0.012
0.000
31.171
43.746
Gradient (mm/g)
0.103
0.160
A4
2 48.538
Gradient D3 (mm/g)
Average (mm/g)
A3
0.132
0.136
0.006
Formulation
A1
Sample 1:
Sample 2:
= 2.181 mm/s
= 0.151mm/s Average gradient = 0.136 mm/s
Sample 2: Formulation
Sample 1:
= 30.761 mm/s Average gradient = 0.132mm/s
AD
= 0.012mm/s Formulation
AC
Sample 1:
Sample 2:
= 0.120mm/s
= 0.000mm/s Average gradient = 0.006mm/s
DISCUSSION
gives each product the characteristic of flavour, t aste, colour and provides at least part of the pectin and ac id needed for successful gel formation. Fruits that are rich in flavou r are best because the large proportions pro portions of sugar necessary for proper consistency and good keeping quality dilute the fruit flavour. A good goo d jam should be bright and rich r ich in colour reflecting the colour of the fruit. It should have the t he full flavour of the fruit used and set without becoming too stiff. Fruits that have low taste and flavour can be mixed with those that t hat have a stronger taste. Fruit
As state state earlier earlier in the introduction, the ingredients ingredients used will effect the jam quality. For the main ingredient used, the t he pineapple is classified into 2 which are ripe and unripe pineapples. These 2 are separated because the ripeness of fruits will give the different amount of pectin. The pectin is very important in jam making because it will act as thickener so that the fruit particles, sugar, and others. Since pectin in fruit is not enough, we used the commercial pectin our pineapple jam. During ripening, pectin is broken down by the enzymes pectinase and pectinesterase; in this process the fruit becomes softer as the middle lamella breaks do wn and cells become separated from each other. o ther. A similar process of cell separation caused by pe ctin breakdown occurs in the abscissi a bscission on zone zo ne of the petioles of deciduous dec iduous plants at leaf fall. Pectin is a chain of polygalacturonic acid which has a molecular weight up to 150000. As a primary gelling agent in jam or jelly or other fruit products, pectin is suitable in use with a tot al soluble o solid of 65-75 Brix with the pH of 2.9 to 3.2.
The chemical structure of pectin Since the monomer of pectin is a carboxyl group, it needs to remain as ±COOH group in + our jam product. We need to ensure it will not break down into COO and H so that the structure of pectin will remain and do not break. The breakdown of the carboxyl group will make the jam cannot hold the water wat er and other substance thus will produce wat ery layer in our jam. The production of water layer in our ou r jam will make it spoil easily because the water will provide a suitable condition for microbial growth. To maintain the pectin structure, we need to adjust the pH of our product. The addition of + acid which high in H ion will bind to dissociated COO that will shift the equilibrium to the left hand side. COOH
-
+
COO + H
Citric acid is added to obtain o btain the correct balance needed to produce the jam or jelly. jelly. Lime L ime and lemon juice are high in citric acid, therefore they are the most prevalent source used. The fruit pulp was adjusted by adding a n amount of citric acid to reach the t he pH of 3.0. This T his was done by using a pH meter. Citric acid can also be obtained by the fermentation of sugars. It will hydrolyze sucrose to invert sugar, thus may avoid recrystallization. Citric acid aids in flavouring by reducing excess sweetness of sugar added. Citric acid gives little sour taste. Besides, citric acid also functions as preservative by lowering the pH value. At low pH, microbial growth is retarded. Hence, the jams produced will be safe from microbial spoilage. spo ilage. In food act 1983, 19 83, permitted sweetener should be added to a jam with the total soluble solid must not less than 65%. For this th is jam processing, we used 550g of sugar for each formulation. The main function of sugar is to work with the pectin and fruit acids to form the gel structure of the jam. It also contributes to the flavour of the product and has a firming effect on the jam. Sugar also a lso may act as a preservative that helps maintain maintain the beautiful color of the fruit and inhibits mould growth. Preservation of food does not only determined by the o smotic pressure of sugar solution, but also by the wat er activity values in the liquid phase of product pro duct which can be lowered by the addition of sugar and by evaporation which may reduce the water activity to 0.848. This T his value however does not protest product from mould mould and osmophile o smophile yeast attack. Preservation is also achieved by lowering water content to 30%, increasing the sugar level to 60-65% and acid to a level where microorganisms cannot grow. The sugar will "tying up" the water so that most microorganisms cannot grow. Tying up the water makes the jam lower lower in water activity thus provide a bad co ndition for microorganisms to grow. We need to u se the allowed amount of sugar rightly because the t he lower amount of sugar used will w ill upset the balance of fruit, sugar and pectin to form a good gel. In acidic condition, during boiling in the cooker, sucrose will undergo inversion producing dextrose and laevulose. The reaction of sucrose inversion is catalyzed by hydrogen ions. +
+
C12H22O11(sucrose) + H2O + H => C6H12O6(fructose) + C6H12O6(glucose) + H
These invert sugars are vital in retarding the crystallization of sucrose in jams. It is essential to balance the amount between sucrose and invert sugar as low amount of invert sugar will cause crystallization of sucrose while too much invert sugar will cause granulation of dextrose. The optimum percentage of invert sugar is between 35-40% of the total sugar in the jam. In high acidic condition, inversion can be kept down by using buffers, while for in low acidic condition, inversion can be increased by acid or invert sugar. Hydrogen ions concentration, boiling time and boiling temperature must control properly as they w ill affect inversion of sucrose.
Water also added to the jam during the processing to homogenize the fruit. The homogenization of fruit is important to distribute the fruit particles all over t he jam. Jam is an intermediate moisture food with water content 30-40% and Aw 0.60-0.90. The water added in this practical must be enough to dissolve pectin and inversion of sucrose. Like sugar, the a mount of water added should not more than listed in the laboratory manual because the higher the water added will contribute to the t he faster the spoilage of the jam.
For the processing of the jam, we begin beg in by removing the pineapple skin and a nd its eyes. Then it is cut into smaller smaller pieces to make it is easier to blend. During blending, water is added to produce the homogenous fruit puree. To provide adjust the pH so that it achieve the required pH for each formulation. The amount of acetic acid added is calculated by using the provided standard. The acetic acid needed for 20g pineapple puree is taken to get the ratio of overall acetic acid should be added for the whole weight of our jam. The pH of the jam that we will produce is 3.0 which is in acidic condition that suitable for for the properties of our jam. jam. Then the pineapple puree may be cook without adding anything because we want to boil it so that the water will evaporated. Mix the pectin with a small portion of o f the sugar. The dry mixing of o f the pectin is important because pectin powder is very difficult difficult to dissolve in water because it clumps together. This property of pectin named heterogenous material and the quality of pectin is depends on the source it was extracted. The re maining sugar added later, about 3 minutes after the p ectin is dissolve. The sugar added later because if the sugar added first first because the sugar will compete with pectin for water, and sugar surely will win the race leaving insufficient water for pect in to solubilize and form or set a good structure to hold the water and fully form a gel. The mixture are stir until it is boil and then t hen it is achieve the time to check the total soluble solid of our jam product. Degree Brix of jam is measured by using a hand refractometer. It will o accept set our sample at 20 C automatically although the temperature of o f the tested jam is higher. o If the total soluble solid does not reach 68 Brix, the heat will continually cont inually supplied to the jam until it is achieved. The total tot al soluble solid needed to ensure to reach the t he point because it is stated in the food act 1953 to have not less 65% total soluble solid. so lid. During jam boiling, all microorganisms are destroyed within the product. o
When the Brix achieve, the heat was cut off and the measured amount of acetic acid is added. Then the jam stirred slowly because we want to reduce the formation formation of bubbles. bub bles. All those bubbles need to be removed because it will effect the jam during storage. Then the jam is ready to fill into bottles. The filling is done while still hot, into clean receptacles which are subsequently sealed, and then inverted so that t hat the hot jam contacts the lid surface. This is done so that spoilage by micro-organisms will not take place during storage. Bottles are kept warm to prevent p revent thermal shock when hot mixture was po ured in. All the bottles
was the inverted back to normal position and being µknock¶ down so that all remaining the bubbles will go up and will not trap and interfere in the setting of o f the jam. The bottles were cooled in the water bath to prevent further sugar inversion. The level o f water must be set lower than the caps so that no cross contamination from water can occur. The bottles were left at room temperature. During cooling, pectin network start to set. For successful jams, a proper ratio of fruit, pectin, sugar, acid and water is needed. To determine the jam characteristic, analysis of water activity and texture of the jam was done. The water activity was done by using Aqu Lab series 3 TE. From the result resu lt of water activity, the formulation A1, A2 and A3 reco rd the lower water activity compared to t he other one, A4. The result obtained like this because formulation A1 and A3 was added with the acetic acid. However the formulation A2 also shows low water activity due to the t he pineapple used is unripe pineapple. The unripe unr ipe pineapple will has slightly acidic pH that will lower t he water activity. Besides that, the unripe pineapple also has a bit higher pectin contain compared to the ripe one. So when the pectin from the fruit will hold the wat er and the activity of the water wat er will be lowered. The water wat er activity of formulation A1 is the lowest because of the u se of unripe pineapple and the addition of acetic acid. In determination of spread ability of the jam, Texture Analyzer was used. The pro be used is 30 degree conical probe which was used to measure the distance in compression till the probe reach/press to 50 gram and the t he graph was recorded (distance vs. time). t ime). The distance for the probe to travel in until one po int where it introduced to 50 gram and sta y constant will determine the softness and the hardness of the jam produced. The higher the t he slope, the higher the spread ability of the jam- sample deform further. Formulation A2 cannot determine the texture while A4 is the lowest due to no addition of acetic acid. Then there is no source of H+ ion that male the jam excessive of the COO ion. The ions will repeal each ot her makes the analyzer move smoothly smooth ly in the samples. It is reversible with the other two formulations. formulations. There are some precauti ons steps have t o be taken t o produce a quality jam :
Make sure that the pineapple fruit we selected is according to the formulation whether ripe or unripe fruit is.
Pineapple should be well we ll blended to get consis co nsistent tent jam.
When boiling the puree, stir it continually.
Make sure that the pH meter, refractometer, texture analyzer and water activity meter have calibrated before using.
Citric acid has to be added after we get the specific Brix.
Pectin and the sugar (1:5 ratios) have to be mixed well before adding to the fruit puree to avoid formation of lump during bo iling. iling.
The sugars have to be added slowly and the soluble solids content have to be checked regularly.
After filling, the bottle should be upside down for 2 minutes for neck bottle sterilization.
Then, the bottles have to knock a little bit to allow the air bubbles removes to upside of the bottle.
CONCLUSION
In conclusion ifferent amount of formulation will give a d ifferent ifferent type t ype of setting of the structure of jam. Formulation A1 is better in terms o f water activity, pH value, pectin network and stability. In order to establish good quality jam, the pH value must be below 3.5, 60-65% of sugar concentration, just ripe fruit, suitable amount of pectin and water must be added or used .
REFERENCE
http://works.bepress.com/cgi/viewcontent.cgi?article=1006&context=georgeamponsahan nor http://www.scientificpsychic.com/fitness/carbohydrates2.html http://practicalaction.org/practicalanswers/product_info.php?products_id=156 http://www.answers.com/topic/times-topics-jams-and-jellies http://www.kraftcanada.com/en/cookingtips/TipsTechniques/JamMaking/R oleOfSugar.aspx oleOfSugar.aspx http://www.gtz-treecrops.org/Downloads/Manuals/Processing/Module4.pdf
SCHOOL OF INDUSTRIAL TECHNOLOGY FOOD
FOOD
TECHNOLOGY DIVISION
PROCESSING & FOOD PRESERVATION IMA 312 & IMA 313 SESSION 2010/2011 PROCESSING O F FRUIT JAMS
