Angiotensin-I converting enzyme inhibitory and antioxidant activities of protein hydrolysates from Phaseolus lunatus and Phaseolus vulgaris seeds

Phaseolus lunatus and Phaseolus vulgaris protein concentrates were hydrolyzed with the enzymes Alcalase® and Flavourzyme® at different reaction times, and the angiotensin-I converting enzyme (ACE-I) inhibitory activity, antioxidant properties and amino acid composition measured in the hydrolysates. With Alcalase®, the highest degree of hydrolysis (DH) in P. lunatus was 37.94% at 45 min, and in P. vulgaris was 49.48% at 30 min. With Flavourzyme®, the highest DH's were 22.03% and 26.05%, respectively, both at 90 min. ACE-I inhibitory activity in the Alcalase® hydrolysates was IC50 = 0.056 mg mL−1 for P. lunatus at 90 min, and IC50 = 0.061 mg mL−1 for P. vulgaris at 60 min. In the Flavourzyme® hydrolysates this activity was IC50 = 0.0069 mg mL−1 for P. lunatus at 90 min and IC50 = 0.127 mg mL−1 for P. vulgaris at 45 min. In SDS-PAGE, the hydrolysates exhibited low molecular weight bands. Antioxidant activity was 11.55 mmol L−1 TEAC mg−1 protein for P. lunatus with Flavourzyme® at 90 min and 10.09 mmol L−1 TEAC mg−1 protein for P. vulgaris with Alcalase® at 60 min. Amino acid composition exhibited high amino acid hydrophobic residues content.