Study on the Optimization of the Technological Conditions of Walnut Protein Hydrolyzeed by Papain and the Antioxidative Activity of Its Hydrolysate

[Objective] The research aimed to investigate the optimum technological conditions of walnut protein hydrolyzed by papain and antioxidative activity of its hydrolysate.[Method] The optimum technological conditions of walnut protein hydrolyzed by papain were confirmed by orthogonal experiment.The enzyme hydrolysate was separated by Sephadex G-25 gel filtration and the antioxidative activities of hydrolysate were studied through determining the scavenging activities of hydroxyl and superoxide anion free radicals.[Result] The optimum conditions for the papain hydrolysis of walnut protein were as follows: the temperature of 55 ℃,substrate concentration of 5%,enzyme concentration of 60 000 U/g and pH of 8.0.When the hydrolysis degree was 38.4%,the scavenging rate of its enzymolysis products to hydroxyl free radicals superoxide anion free radicals were 22.5% and 46.4% respectively.Four fractional peptides were obtained from hydrolysate by Sephadex G-25 gel filtration.Among them,the scavenging capability of the peptide C was the biggest.[Conclusion] The papain hydrolysate of walnut protein had certain antioxidative activity.