Optimization of Process Conditions for Production of Angiotensin I-Converting Enzyme (ACE) Inhibitory Peptides from Vital Wheat Gluten using Response Surface Methodology

The degree of hydrolysis (DH) and angiotensin I-converting enzyme (ACE)-inhibitory activity of vital wheat gluten (VWG) hydrolyzed using Alcalase were investigated using Box-Behnken response surface methodology (RSM). The mean responses were fitted to a second order polynomial to obtain regression equations. The enzyme-substrate ratio and the hydrolysis time increased the DH significantly (p<0.05). The substrate.concentration was the only significant linear term leading to an increase in ACE-inhibitory activity. The optimized conditions of a substrate concentration of 5.04%, an enzyme-substrate ratio 5.94%, and a hydrolysis time 30.79 min gave a point prediction of a 12.74% DH and 82.28% ACE-inhibitory activity. Analytical results from confirmatory experiment were a 12.22%+/-0.5 DH and a 78.93%+/-1.07 ACEinhibitory activity. The optimized conditions of the study provide useful information to the functional food and beverage industries to enhance the anti-hypertensive activities of peptides from VWG.