Abstract: Objective: To optimize trypsin (PTN 6.0S) hydrolysis conditions of small yellow croaker for preparing antioxidant peptides. Methods: The optimization was performed using one-factor-at-a-time method and response surface methodology based on DPPH radical scavenging activity. Results: The optimal hydrolysis conditions were substrate concentration of 4.2 g/100 mL, enzyme-to-substrate ratio of 6‰, hydrolysis time of 19 h and hydrolysis temperature of 52 ℃. Maximum DPPH scavenging rate was obtained under the system of pH 7.0, reaching (46.90 ± 0.3)%. Response surface analysis showed that hydrolysis time had a significant effect on antioxidant activity of products and that the interactions between hydrolysis temperature and enzyme-to-substrate ratio, between hydrolysis time and substrate concentration, and between enzyme-to-substrate ratio and substrate concentration were complicated.

Key words: small yellow croaker, antioxidant peptides, response surface methodology, DPPH radical