Method of Ye, Xu, Chen, Yang and Lin (2010) with minor modification was used.
Sample solutions of different concentrations(1 mL) and 10 g/100 mL yolk homogenate (w/v) (0.5 mL) prepared by 1.15 g/100 g KCl solution were evenly blended in the tube, added with 2 mL distilled water, 1.5 mL glacial acetic acid (20 mL/100 mL pH 3.5) and 1.5 mL TBA (0.8 g/100 mL) that contained 1.1 g/100 mL SDS, evenly mixed and then put in 95 C waterbath for 60 min.
After being cooled to room temperature, the samples were added with 5 mL butanol, and centrifuged at 1610 g for 10 min. The supernatant was obtained to determine the absorption value AT at 532 nm.
Using the distilled water instead of the sample solution as control, AC was measured by the same method.