Abstract: Taking hydroxyl radical-scavenging capacity of hydrolysates as the index, the optimal hydrolysis process for the protein from Actinidia arguta Sieb. et Zucc by alkaline protease was explored by response surface methodology (RSM) to prepare antioxidant polypeptides. Meanwhile, the correlation between the degree of hydrolysis (DH) and the hydroxyl radical-scavenging capacity of polypeptides was examined. The results showed that the optimal hydrolysis parameters of alkaline protease enzyme were hydrolysis temperature of 50 ℃, hydrolysis pH of 9, enzyme addition amount of 4000 U/g, and hydrolysis time of 3 h. Under the optimal hydrolysis condition, the DH was up to 25.08%. In addition, the hydroxyl radical-scavenging rates of the hydrolysis products from the protein of Actinidia arguta  subjected to hydrolysis for 1, 2, 3, 4 h and 5 h at the optimal hydrolysis conditions were 8.69%, 24.67%, 28.04%, 25.82% and 26.65%. The product achieved at 3 h hydrolysis revealed the strongest hydroxyl radical-scavenging rate.

Key words: Actinidia arguta Sieb. et Zucc, anti-oxidant peptides, hydrolysis degree, clearance rate