Determination of Thiobarbituric Acid Value

Thiobarbituric acid (TBA) value was determined according to the analytic methods specified by AOCS Official Method Cd 19-90 (AOCS, 2009). Egg yolk lipid (200 mg) was dissolved in 1-butanol solution and was diluted to 25 mL. Sample solution (5 mL) was taken to the lab graduated glass test tube with ground-in glass stopper with pipette and 5 mL TBA reagent was added. The mixture was heated for 2 h in 95°C water bath to turn pink color. Then it was cooled to room temperature with running water. The absorbance of sample solution (A) was measured at 530 nm after it was calibrated to spectrophotometer zero point with distilled water. The blank test was done without adding sample. The absorbance of the blank solution was B. The value of TBA was calculated as follows:

Where A is the absorbance of the test solution, B is the absorbance of the reagent blank, m is the mass of the sample (mg), 50 is a valid factor if the volume of the volumetric flask is 25 mL and the cuvette width is 10 mm.

In the case of low blank values (0.05), the absorbance of the test solution can be measured directly against distilled water. The value is then calculated as follows: