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.