Antioxidative peptide derived from enzymatic digestion of buffalo casein

Bioactive peptides have been defined as specific protein fragments that have a positive impact on body functions or conditions and may ultimately influence health. We scrutinised the antioxidative property of peptides from buffalo casein digested with pepsin, trypsin, chymotrypsin alone and in combinations. Casein hydrolysates were subjected to ultrafiltration followed by reversed phase-high performance liquid chromatography (RP-HPLC). The antioxidant properties of casein, its hydrolysates and synthetic peptides, was assessed using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid). The fraction with highest Trolox equivalent antioxidant capacity (TEAC) was selected for further study. TEAC of casein was 0.862 ± 0.11 μmol mg−1, while it is highest for pepsin-trypsin hydrolysates. The 1 kDa permeate of pepsin-trypsin hydrolysates possessed the highest antioxidant activity and it was resolved into 16 fractions by RP-HPLC. Antioxidant activity fraction 11 was highest and on custom sequencing yielded 4 peptides, of which the synthetic peptide VLPVPQK possessed the highest TEAC (5.71 ± 0.59 μmol mg−1).