ACE inhibitory and antioxidant peptides from Alcalase‐assisted Lactiplantibacillus plantarum L60 and Lacticaseibacillus rhamnosus LR22 fermentation of goat milk: Optimization and identification

ACE inhibitory and antioxidant peptides from goat milk fermented by Lactiplantibacillus plantarum L60 and Lacticaseibacillus rhamnosus LR22 with Alcalase were optimized through Box–Behnken Design. The effects of enzyme addition, fermentation time, and temperature on DPPH free radical scavenging rate and ACE inhibition rate were studied. The optimum conditions are to add 0.15% enzyme and ferment at 37°C for 12 h, contributing to DPPH free radical scavenging rate of 75.17% and ACE inhibition rate of 84.15%. Compared with the control, it increased by 16.87% and 22.74%, respectively. The bioactive peptides below 3 KDa were obtained by ultrafiltration and identified by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The results demonstrated that both exist three identical peptides: FFDDK, NMAHIPR, SCQDQPTTLAR. There are eight identical peptides in goat milk fermented by two probiotics. This study will contribute to the production of functional fermented dairy products with high ACE inhibitory and antioxidant properties. Practical applications ACE inhibitory and antioxidant peptides have the functions of relieving elevated blood pressure and scavenging free radicals in the body, respectively. In this study, the process of Alcalase-assisted two probiotics in fermentation was optimized, and ACE inhibition and DPPH free radical scavenging rate are significantly improved. There were three same peptides in five goat milk containing bioactive peptides and they mainly derived from whey protein and casein of goat milk, which indicates the enzymes produced by different probiotics have the same restriction sites.