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

  • Blender
  • Glass funnel
  • Measuring cylinder
  • Test tubes
  • Volumetric flask
  • Glass beakers
  • Spectrophotometer
  • Water bath
  • Distilled water bottle
  • Whatman No.1 filter paper (18.5 cm dia.)

Reagents required

  • Thiobarbituric acid
  • Acetic acid
  • Trichloro acetic acid
  • Distilled water

Preparation of thiobarbituric acid reagent

  • TBA reagent is prepared by dissolving 0.2883 gm of thiobarbituric acid in sufficient quantity of 90% acetic acid by slightly warming the solution. The volume is then made up to 100 ml with 90% acetic acid.

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