Effect of processing conditions and in vitro protein digestion on bioactive potentials of commonly consumed legumes

The antioxidant properties and ACE inhibitory activity of green gram, horse gram, lentil, chickpea, cowpea, black pea and white pea were evaluated before and after different processing conditions and in vitro protein digestion (IVPD). Chemical assays indicated that unprocessed horse gram had the highest antioxidant activity. The process of soaking decreased radical scavenging activity (RSA), total antioxidant capacity (TAC), ferric ion reducing power (FRAP) and metal ion chelation activity (MICA) in all the legumes. Cooking of the soaked seeds led to further decreases in these activities. Germination improved MICA in chickpea and lentil as well as TAC in all the legumes except for white pea. IVPD increased RSA and TAC of all the legumes by 2-4 folds, while FRAP and MICA in selective legumes showed a significant contribution from the peptides released due to hydrolysis of proteins. The scavenging and reducing activities in this legume as well as other legumes were correlated with free phenolics content. However, in contrast to the chemical assay, biological assays showed no such correlation. Significant ACE inhibitory activity was observed only after IVPD of the legumes.