2.5.6. ABTS Radical Scavenging Assay

The radical scavenging activity of protein fractions and enzymatically hydrolysed protein fractions was evaluated by ABTS radical cation decolourisation assay according to Rajurkar and Hande [36]. ABTS⁺ cation radicals were produced by the reaction of 2.45 mM potassium persulphate and 7 mM ABTS in water at a ratio of 1:1 and kept in the dark for 16 h before use at room temperature. The obtained ABTS⁺ solution was diluted with methanol to reach an absorbance of 0.700 at 734 nm spectrophotometrically. ABTS⁺ solution (3.995 mL) was mixed with a protein fraction (5 µL) (10 mg protein per ml distilled water) and kept in the dark room. After 30 min, the absorbance was measured at 734 nm. Trolox (0.05–1.00 mg/mL) was used as standard to obtain a calibration curve. The antioxidant activity in protein fractions was expressed as equivalents of Trolox (TE) in mg per 100 g of protein.