Comparative studies on ACE inhibition, degree of hydrolysis, antioxidant property and phenolic acid composition of hydrolysates derived from simulated in vitro gastrointestinal proteolysis of three thermally treated legumes.

Three phenolic-rich legume varieties underwent in vitro simulated gastrointestinal proteolytic digestion after a wide range of thermal treatments. Total phenolic content (TPC), DPPH free radical scavenging activity (DPPH), degree of hydrolysis (DH), angiotensin-I converting enzyme (ACE) inhibitory activity of hydrolysates showed significant differences among thermal treatments. TPC values of hydrolysates were significantly (p < 0.05) higher than their corresponding undigested counterparts. The DPPH values were significantly (p < 0.05) lower than their corresponding undigested counterparts. DH had no correlations (p > 0.05) with ACE inhibitory activity for all three legumes. When compared with undigested legumes, the simulated gastrointestinal tract proteolytic digestion induced marked changes not only in the content, but also in the type of individual free phenolic acids. The present study clearly implied that literature data of phenolics and their potential health benefits derived from undigested legumes cannot accurately represent the real situations after the digestion process.