Antioxidant and antibacterial activities of peptide fractions from flaxseed protein hydrolysed by protease from Bacillus altitudinis HK02

Flaxseed protein (FP) hydrolysates by crude protease of strain Bacillus altitudinis HK02 were further separated into five fractions by ultrafiltration membranes with a molecular weight cut-off of 10, 5, 3 and 1kDa for the analysis of antioxidant activities and antibacterial ability. The results demonstrated that the fraction of 1- to 3-kDa peptides exhibited higher antioxidant activities on the free radical-scavenging ability and the reducing power than those of Vit C, Vit E, BHA and other fractions. The fraction with a low molecular weight (<1kDa) of peptides demonstrated the highest ferrous ion-chelating ability and a higher inhibition of lipid peroxidation than BHA and other fractions. Moreover, it also exhibited the best growth inhibition of Pseudomonas aeruginosa and Escherichia coli. The results, including the concentration-dependent effect of peptides fractions, demonstrated that it is feasible to derive functional ingredients of natural antioxidants along with antimicrobial activity from FPs hydrolysed by protease from B.altitudinis HK02.