ACE inhibitory activity and salt-reduction properties of umami peptides from chicken soup

Angiotensin-I-converting enzyme (ACE) inhibitory activity and salt-reduction properties of umami peptides identified in chicken soup were investigated. The ACE inhibition rate of TPLVDR (91.22%) and AEINKILGN (81.26%) was significantly higher than other umami peptides, and their semi-inhibitory concentration was 0.017 mM and 0.034 mM, respectively. After in vitro digestion, the inhibitory activity of AEINKILGN and TPLVDR decreased, but the original sequences were still detected. The docking results showed that AEINKILGN and TPLVDR mainly interacted with Zn2+ and key sites (His353, Lys511and Glu411) in the active pockets of ACE through hydrogen bonds, which was crucial to the ACE inhibitory activity. Based on response surface methodology and sensory analysis, saltiness and palatability models were established to investigate the salt-reduction effect. The optimal level of AEINKILGN was about 1.16 mg/mL in 0.44% salt solution. And the TPLVDR was applicable to the low salt solution (0.1-0.2%) at a concentration from 0.23 to 0.29 mg/mL.