Abstract: Alkaline protease was chosen by the effect of gastrointestinal fluid simulation which was used to predict the activity in vivo of silkworm pupae protein. Response surface method (RSM) was employed to optimum the optimal alkaline protease enzymolysis procedure of silkworm pupae protein for antioxidant peptides with high reducing power. Antioxidant activity of enzymolysates was assessed with reducing power and scavenging effects against ·OH and DPPH·radicals. Results show that the optimum conditions are as follows: pH at 8.30, quantity of alkaline protease at 15.34 μL(1 902 U), temperature at 50.47 ℃ and time at 2.45 h. Under the optimum conditions, the predicted total reducing power of 2.0 mg silkworm pupae protein/mL enzymolysates was 0.434. On the basis of the optimum conditions of the enzymolysates, the half-scavenging concentration IC50 values of ·OH and DPPH·radicals were 4.51 and 4.24 mg/mL respectively.

Key words: antioxidant peptides, enzymolysis, response surface method (RSM), silkworm pupae protein