Optimization for preparation conditions and antioxidant activity in vitro of polypeptide fermentation by Bacillus subtilis from adlay bran
Using adlay bran as raw material,the polypeptides were prepared from adlay bran by Bacillus subtilis fermentation.With hydrolysis degree as evaluation index,the fermentation condition was optimized by single factor and orthogonal experiments,and the in vitro antioxidant activity of adlay bran polypeptide was determined.The results revealed that the optimal fermentation conditions of adlay bran were as follows:fermentation time 24 h,inoculum 7%,temperature 39 ℃,and initial pH 7.0.Under the optimized conditions,the hydrolysis degree reached 21.33%.The IC50 values of adlay bran peptides obtained under the optimized conditions for scavenging 1,1-diphenyl-2-picrylhydrazyl(DPPH)radicals,hydroxyl radicals,2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS)radicals,and superoxide anions radicals were 7.23 mg/ml,4.47 mg/ml,3.45 mg/ml and 7.33 mg/ml,respectively,indicating that the adlay bran peptides prepared by microbial fermentation had better in vitro antioxidant activity.