Efficient enzymatic production of angiotensin I-converting enzyme inhibitory peptides from three protein-rich materials by electrolyzed water pretreatment

Three protein-rich materials were pretreated with a self-designed alkaline electrolyzed water (AEW) pretreatment equipment to promote the release of angiotensin I-converting enzyme (ACE) inhibitory peptides by improving hydrolysis efficiency. According to degree of hydrolysis (DH) and ACE inhibitory activity, defatted walnut meal (DWM) was selected to study antihypertensive activity by hydrolysis in assistance of AEW pretreatment. It was found DWM pretreated with AEW at pH 11.5 followed by Alcalase hydrolysis exhibited the highest DH (21.96%), protein recovery rate (94.76%), and ACE inhibitory activity (IC 50 of 0.137 mg/mL), in which AEW pretreatment resulted in the transformation of α-helix and β-turn to random coil and the destruction of hydrogen bonds to expose more cleavage sites to enhance hydrolysis efficiency. Thereafter, ACE inhibitory peptides GIENYRVV (IC 50 of 0.102 mg/mL) and AGRISTVNSHTLPVL (IC 50 of 0.20 mg/mL) were identified from the hydrolysate. Overall, AEW pretreatment was an innovative strategy to promote the release of antihypertensive peptides during hydrolysis.