Enzymatic preparation and functional evaluation of antioxidant peptides derived from silk sericin

Preparation of sericin peptide by six proteases and its antioxidant activities evaluated by ABTS system were studied. The results show that Alcalase is a perfect protease to prepare sericin peptide. Effect of hydrolysis time, substrate concentration, hydrolysis temperature, pH value and ratio (E/S) on preparation of sericin peptide with Alcalase were studied by single factor analysis. The regression models were established with factors and the indexes, including of degree of hydrolysis(DH) and antioxidant activities. The results indicate that optimal hydrolytic conditions for preparation of sericin peptide by Alcalase are as follows: hydrolytic time 240 min, substrate concentration 2%, temperature 55℃, pH value 8.5 and ratio (E/S) 2.375%. Under this condition, the DH is 33.35% and ABTS scavenging activities is 43.19%. The work will be a base for development of antioxidant functional food production and provide a method for potential exploitation and utilization of silk sericin.