Abstract:In this paper，the response surface analysis method was used to optimize the conditions during the preparation of flax peptides.Flaxseed meal was used as the raw material，through the screening of eight proteases，while the polypeptide yield and xanthine oxidase inhibitory activity were the main detection indicators.The amount of enzyme added，enzymatic hydrolysis temperature，pH value and material were studied through single factor experiments.The influence of the liquid ratio and enzyme hydrolysis time on the inhibitory activity of xanthine oxidase and peptide yield of flax protease hydrolysate were also examined.The results showed that the optimal conditions for the preparation process were an enzyme addition of 4 060.17 U/g，enzymatic hydrolysis pH value of 10.5，enzymatic hydrolysis temperature of 49.59℃，enzymatic hydrolysis time of 5.18 h and material-to-water ratio of 1∶20 （g/mL）.Under these conditions，the yield of enzymatically hydrolyzed peptides was 67.24%.Under the optimal conditions，the biological activity of flax peptides inhibited xanthine oxidase by 60.04%，the scavenging rate of·OH free radicals was 90.65%，and the scavenging rate of ABTS+free radicals was 92.68%.Compared with commonly used antioxidants，the ABTS+free radical scaveng－ing ability of the polypeptide was significantly lower than vitamin C Additionally，the·OH free radical scavenging ability of flax polypeptide was not significantly different from that of vitamin C.The results of the antioxidant activity and xanthine oxidase inhibitory activity experiments show that the flax polypeptide prepared by alkaline protease enzymatic hydrolysis had better antioxidant activity and uric acid lowering activity.