Antioxidant properties of peptide fractions from silver carp(Hypophthalmichthys molitrix) processing by-product protein hydrolysates evaluated by electron spin resonance spectrometry

摘要

Silver carp processing by-product protein is usually discarded as an industrial solid waste. In this study the protein was recovered using a pH-shift method, after which seven commercial proteases were sepa-rately employed to prepare antioxidative hydrolysates. Among the hydrolysates, pepsin hydrolysates, which had the highest free radical-scavenging activity, were further separated into five peptide fractions, SCPH-l (>10 kDa), SCPH-ll (5-10 kDa), SCPH-III (3-5 kDa), SCPH-IV (1-3 kDa), and SCPH-V (<1 kDa), by using ultrafiltration. The antioxidative properties of the peptide fractions were investigated, using a free radical-scavenging assay, by electron spin resonance. The results show that SCPH-V had the highest scav-enging effects on DPPH (l,l-diphenyl-2-picrylhydrazyl), hydroxyl and superoxide anion radicals. SCPH-V had potent antioxidant activity in the prevention of the peroxidation of linoleic acid and alleviation of H_2O_2-induced oxidative stress in human intestinal epithelial caco-2 cells. The results indicated that the antioxidant capacity of silver carp by-product hydrolysates could be enhanced by ultrafiltration.