Improvement of the ACE-inhibitory and DPPH radical scavenging activities of soya protein hydrolysates through pepsin pretreatment

摘要

This study aimed to investigate the effect of pepsin pretreatment on the ACE-inhibitory and DPPH radical scavenging activities of soya protein hydrolysates prepared with alcalase and protamex. The protein recovery, TCA-soluble peptide content, surface hydrophobicity, particle size and zeta potential were evaluated. Results showed that the hydrolysates exhibited varying ACE-inhibitory (i.e. the highest value 72.6％ by alcalase and 84.3％ by protamex) and DPPH radical scavenging activities (i.e. the highest value 51.9％ by alcalase and 51.7％ by protamex). Pepsin pretreatment could make soya proteins more susceptible for hydrolysis, and the results showed that the ACE-inhibitory and DPPH radical scavenging activities of the resultant hydrolysates were improved. A highly significant positive correlation between ACE-inhibitory and DPPH radical scavenging activities was observed in the alcalase hydrolysates, while no significant correlation among other treatments. The physical properties of hydrolysates, that is surface hydrophobicity, particle size and zeta potential, could influence their ACE-inhibitory and DPPH radical scavenging activities.