Production of Angiotensin-I-Converting Enzyme inhibitory peptide from goat milk casein: Optimization conditions of complex protease hydrolysate by response surface methodology and purification

Abstract

Food-derived Angiotensin-I-Converting Enzyme (ACE)-inhibitory peptides have safety advantages over synthetic peptides. The application of complex enzymatic (alcalase and trypsin) in producing such peptides from goat milk casein seldom be focused. In this study, the pH, complex protease ratio (CPR) and enzyme to substrate ratio (E/S) were optimized by Response surface methodology (RSM). The optimized conditions were: pH 8.4, CPR 1:1, and E/S 8.5%. In these conditions, the ACE-inhibitory activity of the obtained hydrolysates reached 91.99%. The response model was qualified to predict the reaction optimization. Hydrolysate fragments were purified consecutively. A fraction G2-2a exhibited highest ACE-inhibitory activity 93.50% with IC50 value of 72.14 μg/mL.