Abstract:Small molecular peptides were prepared via enzymatic hydrolysis of eggshell membrane，and their biological activities were studied.Using degree of hydrolysis as the evaluation index，the influence of protease type，enzymatic hydrolysis time，material-liquid ratio，and enzyme addition to the shell membrane polypeptide was determined through a single-factor experiment.Three factors and three levels were optimized by Box-Behnken design（BBD）for enzymatic hydrolysis condition.The molecular weight distribution of shell membrane polypeptide was determined via high efficiency gel filtration chromatography.The scavenging ability of shell membrane polypeptide to DPPH·，ABTS+·，·OH，and O2-·was determined.The results showed that the optimum enzymatic hydrolysis conditions were as follows：alkaline protease（AP-200a），enzyme addition 2.4%，feed-liquid ratio 1∶9.5（g/mL），and enzymatic hydrolysis time 5 h.Under these conditions，the degree of hydrolysis of the shell membrane polypeptide was 27.15%；the proportion of small peptides with a relative molecular weight of less than 1 000 Da after hydrolysis was 90.9%；and the scavenging ability of the shell membrane polypeptide on DPPH·and ABTS+·was（93.03±0.51）% and（94.53±0.92）%，respectively，which were equivalent to the effect of VC.However，the elimination ability of·OH and O2-·were（43.33±1.10）% and（53.40±0.70）%，respectively.Therefore，the small molecular peptides obtained by enzymatic hydrolysis of shell membrane peptides were relatively high in number，easily digested，and absorbed by human body，and they had a certain antioxidant activity.