Optimization of dual- enzymatic preparation of antioxidant peptides from zein

In order to prepare antioxidative peptides, zein powder was subjected to stepwise hydrolysis initially with Neutral protease followed by Alcalase. DPPH· cleavage activity and degree of hydrolysis were used to evaluate antioxidative activity of hydrolysates. Furthermore, response surface methodology ( RSM) was employed to optimize hydrolysis conditions, including Alcalase dosage, Neutral protease / Alcalase, and substrate concentration.The modified optimum conditions obtained were as follows: Alcalase dosage of 12880 U / g, Neutral protease /Alcalase of 1 ∶ 4, and substrate concentration of 3.4%. Under the modified condition, DPPH· radical scavenging activity of 42.98% and DH of 32.18% were obtained, and the relative error of forecast value was 1.04%. When the concentration was 20 mg / m L, the DPPH·radical scavenging activity and the hydroxyl radical rate were 85.8% and67% of VC, respectively.