Estimation of TBA
|
ESTIMATION OF THIOBARBITURIC ACID VALUE
|
-
The storage stability of meat is estimated by the extent of oxidative rancidity developed in it.
-
The TBA value is the measure of oxidative rancidity in food and is expressed as a value or number.
-
Rancidity of fat in stored foods is defined as the development of stale off flavour as a result of oxidation of unsaturated fatty acids.
-
Thiobarbituric acid value measures the carbonyl residues resulting from lipid peroxidation.
-
Lipid peroxidation produces oxidative rancidity in foods and can decrease their nutritional quality.
-
The rate of this change depends on initial bacterial load, physical and biochemical change availability of oxygen, temperature of storage and muscle composition.
Apparatus required
Reagents required
-
Thiobarbituric acid
-
Acetic acid
-
Trichloro acetic acid
-
Distilled water
Preparation of thiobarbituric acid reagent
Preparation of trichloro acetic acid extract
-
Twenty g of meat is blended in 50 ml of cold 20% trichloro acetic acid for 2 minutes.
-
The blended contents is rinsed with 50 ml of distilled water, mixed together and filtered through whatman No.1 filter paper and the volume of filtrate is collected in a 100 ml capacity measuring cylinder.
-
The filtrate is termed as trichloro acetic acid extract and is used in the estimation of TBA number and Tyrosine value.
Procedure
-
A 5 ml of TCA extract is mixed with 5 ml of 0.01 M thiobarbituric acid.
-
After mixing, the test tube is placed in boiling water bath (100° C) for 30 minutes.
-
A blank constitutes 5 ml of 10% trichloroacetic acid in another test tube and placed in boiling water bath along with the sample.
-
After 30 minutes the test tubes are to be removed from the water bath and cooled in running water for about 10 minutes.
-
The developed colour is to be measured as absorbance value at 532 nm and expressed as thiobarbituric acid number.
|
Last modified: Thursday, 12 April 2012, 12:23 PM