OIL AND FAT ANALYSIS NOORHIDAYAH ISHAK
Oil and Fat Analysis Analysis •
Why oil and fat products need to be analyze before it been distribute to the consumer? –
To ensure the quality control in the process
–
To determine the cause of product failures
–
To ensure products function and design
Oil and Fat Analysis Analysis 8 types of oil and fat analysis:
Non fatty impurities
Melting, solidification and consistency
Composition analysis
Flavorr, randicity Flavo randicity and stability stability
Color and appearance
Refining and bleaching
Performance testing
Nonsta Non stand ndard ardize ized d met method hodss
on a y mpur
es Non fatty impuritie s
Impuritie s analysis
Insoluble
Filterable Hot plate
Soap analysis
Moisture analysis
Trace material analysis
Turbidimeter
Air oven
Karl Fisher
Vacuum oven
Non fatty impurities (Moisture analysis)
Hot plate method
- 10 g sample heated in beaker with gentle agitation on hot plate until smoking begins
Moisture and volatile matter = The loss in weight between the beginning and the ending sample
Non fatty impurities (Moisture analysis) Air
oven method
accurate, more reliable than hot plate
time consuming approximately
5 grams of a representative sample is weighed into a dried,
tared
moisture dish and dried in the oven for 30 minutes at 101°C (± 1°C). This
procedure
is repeated until a constant weight is determined
The
loss in weight is calculated as the moisture and volatile matter
Non fatty impurities (Moisture analysis)
Vacuum oven method
-similar to air oven method except -vacuum method no to exceed 100 mm of Hg at temperature 20 – 25 deg above b.p of water at the operating pressure until constant weight is obtained in successive 1h drying periods.
Non fatty impurities (Moisture analysis)
Karl Fischer method
-Karl Fischer is an analytical technique used to determine moisture
Non fatty impurities (Moisture analysis)
Karl Fischer method
The titration endpoint is a color change from yellow to brown. brown.
on a y mpur
es Non fatty impuritie s
Impuritie s analysis
Insoluble
Filterable Hot plate
Soap analysis
Moisture analysis
Trace material analysis
Turbidimeter
Air oven
Karl Fisher
Vacuum oven
Non fatty impurities (Impurities analysis)
Foreign material in incoming crude edible oils must be removed to produce an acceptable finished product
Methods to remove impurities:
insoluble impurities
filterable impurities
turbidimeter impurities
Non fatty impurities (Impurities analysis) Insoluble impurities - Dirt, seed fragments and etc insoluble in kerosene or petroleum ether Utilizes the residue from the moisture and volatile matter •
•
-After wash with warm kerosene, the crucible is dried and weighed
Non fatty impurities (Impurities analysis)
Filterable impurities evaluation method
-During processing, undissolved impurities might be present such as salt which formed after the reaction -Methods: filter a standard quantity (500 g) of heated (70 – 90 deg.) oil sample with vacuum suction funnel through Whatman No. 2 filter disc.
Non fatty impurities (Impurities analysis)
Turbidimeter impurities
-Amount of undissolved impurities in oil can be determined using this method -method: sample will be poured into prescribed sample bottle to eliminate air bubbles. Then the sample will be heated to 70oC and allowed to stand at 5 – 10 mins in controlled temp. oven
Non fatty impurities (Impurities analysis)
Turbidimeter impurities cont.
-The turbidimeter readings can be converted to ppm of impurities using a calibration curve
No suitable for meat fats and products containing emulsifiers – contain impurities that cannot be effectively measured by this method
on a y mpur
es Non fatty impuritie s
Impuritie s analysis
Insoluble
Filterable Hot plate
Soap analysis
Moisture analysis
Trace material analysis
Turbidimeter
Air oven
Karl Fisher
Vacuum oven
Trace material analysis
Metals in oils and fats can cause the deterioration of the product quality
Metals usually present in edible oils and fats through the processing level
Most prevalent metals found: copper, iron, calcium, magnesium, sodium, lead, zinc, and nickel
Can be trace by analysis using ICP (Plasma emission spectroscopy
on a y mpur
es Non fatty impuritie s
Impuritie s analysis
Insoluble
Filterable Hot plate
Soap analysis
Moisture analysis
Trace material analysis
Turbidimeter
Air oven
Karl Fisher
Vacuum oven
Soap analysis
In caustic refining, NaOH is added into the oil to react with free fatty acid and produce soaps
Traces of soap in oil after refining and bleaching could poison hydrogenation catalyst.
2 methods available for determining soaps:
-
Conductivity procedure (Cc 15-60)
-
Titration procedure (Cc 17-79)
Oil and Fat Analysis 8 types of oil and fat analysis:
Non fatty impurities
Melting, solidification and consistency
Composition analysis
Flavor, rancidity and stability
Color and appearance
Refining and bleaching
Performance testing
Nonstandardized methods
Melting, solidification and consistency
Most frequently and routinely analysis performed
Helps with quality control and product development – good indications of the mouth feel, overall general behaviour at cool, ambient and elevated temperature
Melting point analysis
Natural fats do not have true melting points
Melting range or melting interval is most appropriate terms
Several melting point procedures have been standardized by AOCS
Melting point analysis
Melting Point Analysis
Capillary melting point
Wiley melting point
Mettler dripping point
Melting point analysis
Capillary melting point
-
Similar with procedure used to determine the melting point of pure organic compound
-
Heated until the fat become clear
Melting Point Analysis
Capillary melting point
Wiley melting point
Mettler dripping point
Melting point analysis
Wiley melting point:
-A tube of 3.5 cm internal diameter is half-filled with boiled water then cautiously topped –off with boiled alcohol so that the latter remains above the water which it forms an interface. -A cold disc of fat added to the tube and when disc softens to become spherical globule –melting point
Melting point analysis
Wiley melting point cont:
-
Disadvantages:
-
-> subjective interpretation in order to determine end point
-
-> Constant attention needed to determine the endpoint
Melting Point Analysis
Capillary melting point
Wiley melting point
Mettler dripping point
Melting point analysis Dripping
point
-use METLLER TOLEDO instrument -Method: 17 drops of melted fats will be put in the sample cup -Put in a freezer for 15 mins -Cold solidified sample warm through the furnace until it becomes fluid enough to flow -When the sample flow, it trip a photoelectric circuit that records the temperature on digital read out.
Melting point analysis •
Dripping point
Melting point analysis
Advantaged of Dripping point
had become a standard in most fats and oil laboratory
fast, reliable result
good correlation with Wiley result
ability to analyse products with low melting points
Solidification Analysis
Solidification of mixed fatty acids: point where a balance is attained between the heat generated and heat lost, which will vary according to rate of crystallization.
Types of evaluation:
Solidification Analysis
Titer test
Cloud point
Cold test
Solidification Analysis
Titer test: measure the solidification point of fatty acid
-
For edible oils and fats, commonly specified for low iodine values hard fat refers to as titer stocks
For inedible fats, used for soap making or as a raw material for fatty acid manufacture
Solidification Analysis
Titer test
Cloud point
Cold test
Solidification Analysis
Cold test: the ability of an oil to resist crystallization by determining the time (in hours) required for the oil to become cloudy at 0°C (32°F).
Method: dry filtered oil is placed in a sealed 4-ounce bottle and submerge into an ice bath.
If the oil remains clear for 5.5 h, the oil pass the cold test.
Solidification Analysis
Titer test
Cloud point
Cold test
Solidification Analysis •
•
Cloud point: is obtained by stirring a sample of fat while it is being cooled until the oil has clouded enough to block a light beam of known intensity. The cloud or congeal point values are more closely related to consistency than melting points
Consistency Analysis
Consistency: impression of resistance
Plasticity: relates to the capacity of the product to be molded
Fat become firmer as the solid content increases
Butter and margarine depends upon the consistency of fat portion and its ability to spread on bread
Consistency Analysis Consistency
evaluation method:
-consistency ratings -penetrations
Consistency Analysis
Consistency rating:
-pressing a finger into the product/ squeeze the product in the hand -Still applicable and effective -required an experienced evaluator
Consistency Analysis
Penetration
-
Widely used method to measure the consistency of plasticized shortening or margarine
-
Using grease penetrometer
-
Measured at different temp. to determine the plastic range of the sample
-
Perfect plastic range: penetration at all temp
same
Oil and Fat Analysis 8 types of oil and fat analysis:
Non fatty impurities
Melting, solidification and consistency
Composition analysis
Flavor, rancidity and stability
Color and appearance
Refining and bleaching
Performance testing
Nonstandardized methods
Composition analysis
Usually done by using wet chemical analysis (classical method)
Saponification value Iodine value refractive index
Composition analysis
fatty acid composition calculated iodine value Emulsifier analysis
Tocopherol analysis Antioxidant analysis
Composition analysis
Saponification value
-
Measure the alkali-reactive groups in fats and oils
-
Useful in predicting type of glycerides
-
Glyceride with short-chain fatty acid have higher saponification values than long-chain fatty acid
-
Example: vegetable oils and animal fats has same range of saponification value: 180 - 200
Saponification Value Saponification - hydrolysis of ester under alkaline condition. O H2 C
O
HC H2 C
C O
R
O
C O
R
O
C
R
H2 C
OH O
+
3 KOH
HC
OH
H2 C
OH
+
3R
C
OK
Composition analysis
Iodine value
-
Measure the unsaturation of fatty acid
-
But, cannot define specific fatty acid
Refractive index
-measure the change in unsaturation as the fat or oil is hydrogenated -A refractometer with temperature control at 25 deg. is used -A refractive index decrease with no. of double bonds present in fatty acids
Differential between saturate and unsaturated fatty acid Saturate
Unsaturated
Fatty acid chain are straight
Fatty acid chain are bent in some place
No double bond
Contain double bond
Solid in room temperature
Liquid in room temperature
Palmitic fatty acid
Oleic fatty acid
Butter, palm nut oils, coconut
Olive oil, fish oils, peanut, linseed, and cottonseed oils
Composition analysis
Fatty acid composition
-
Determined by using GC
Calculated iodine value
-
Measure the unsaturation in fatty acid
-
Calculated from fatty acid composition analysis
Composition analysis
Triglyceride structure
HPLC procedures used to determine relative amounts of glycerides present in a fat
O
O H2C
OH
HC
OH
H2 C
OH
Glycerol
+
HO
C O
R
HO
C O
R
HO
C
R
3 Fatty Acids
H2 C
O
C O
R
HC
O
C R O
H2 C
O
C
R
+ 3 H2O
Composition analysis
Antioxidant analysis
-To measure the amount of synthetic antioxidant used in fat and oil products -Ensure the amount of synthetic antioxidant is beyond the safety limit (e.g: US FDA allow max. limit of 100 ppm for meat products) -Use GC or HPLC for analysis
Composition analysis
Tocopherol analysis
Vegetable oils contain tocopherols, which are natural antioxidants that retard oxidative rancidity.
The instrumentation and procedures evaluated have involved colorimeters, paper chromatography (PC), TLC, column chromatography (CC), GLC, GLC/mass spectrometry (GLC/MS), and HPLC separation techniques
Oil and Fat Analysis 8 types of oil and fat analysis:
Non fatty impurities
Melting, solidification and consistency
Composition analysis
Flavor, rancidity and stability
Color and appearance
Refining and bleaching
Performance testing
Nonstandardized methods
Flavor, rancidity and stability
Customer use organoleptic evaluations to judge the quality of fat and oil
Organoleptic:
evaluation of oil products has long been recognized as the most sensitive method of assessing quality, but it is also recognized that these evaluations generally lack precision and reproducibility
avor, ranc
Flavor analysis method
-
Sensory evaluations
-
Volatile flavor analysis
y an s a
y
Flavor analysis method
Sensory evaluations
-most common method of grading finished oil quality -Experienced taster/ flavorist rate the flavor of the oil according to established intensity scale. -time consuming, expensive
avor ana ys s me o
Volatile flavor analysis
-
Use GC analysis
-
E.g:
Besides lactic acid, acetaldehyde, acetone, and 2-butanone contribute most to the typical aroma and flavor of yogurt. Extended storage of yogurt causes off-flavor development, which is mainly attributed to the production of undesired aldehydes and fatty acids during lipid oxidation
Rancidity analysis
The major cause of rancidification of oil and fats are:
1)
Oxidation
2)
Hydrolysis
Factors that contribute to the rancifidication and formation of off-flavors:
1)
Temperature
2)
Light
3)
Moisture
4)
Metals
5)
Oxygen
Rancidity The sharp pungent odours mixed with stale and musty odours (unpleasant smell)
Hydrolytic Rancidity .
Hydrolytic rancidity results in the formation of free fatty acids and soaps (salts of free fatty acids) and is caused by either the reaction of lipid and water in the presence of a catalyst or by the action of lipase enzymes.
Oxidative Rancidity .
Oxidative rancidity results from more complex lipid oxidation processes which involve free radical reactions. The processes are generally considered to occur in three phases: 1) initiation or induction phase, 2) propagation phase, and 3) termination phase.
Rancidity
Analysis to measure:
a)
Peroxide value
b)
Anisidine value
c)
Free fatty acid and acid value
Rancidity analysis 1.
Peroxide Value •
•
–
major cause by oxidation of lipid
Hydroperoxides formed by the reaction between oxygen and the unsaturated fatty acids are the primary products of this reaction. Hydroperoxides have no flavor or odour but break down rapidly to form aldehydes, which have a strong, disagreeable flavour and odour
Rancidity analysis 2. •
•
•
Anisidine value The anisidine value measures the amount of α and β unsaturated aldehyde present in the oil. The method is based on present of acetic acid, panisidine reacts with aldehydic compound in an oil, producing yellowish reaction products. The color intensity depend on the amount of aldehydic compound present.
3.
Acid Value •
•
The flavors resulting from FFA developed depend on composition of fat thus, rancidity analysis can be measure by FFA Number of mgs of KOH required to neutralize the Free Fatty Acids in 1 g of fat.
AV =
ml of KOH x N x 56 Weight of Sample
= mg of KOH