Nutritional and antinutritional composition, in vitro amino acid availability, starch digestibility and predicted glycemic index of differentially processed mucuna beans (Mucuna pruriens var. utilis): an under-utilised legume

The effects of different solutions, water, 0.07% sodium bicarbonate, 0.1% ascorbic acid and 3% moringa leaf powder in water, and soaking, followed by autoclaving, on the proximate composition and antinutrients, in vitro amino acid digestibility, starch hydrolysis index (HI) and glycemic index (GI) of Mucuna pruriens var. utilis seeds were evaluated. Even though none of the processing techniques affected the proximate composition on gross energy value, they significantly (P<0.05) reduced the levels of various antinutrients, such as total phenolics, tannins, phytates, saponins, l-dopa, trypsin inhibitor (TI), chymotrypsin inhibitor (CI) and lectin activities of the respective samples. Nonetheless, all the processing methods improved the total protein digestibility and individual amino acid availabilities, particularly those of methionine, tyrosine, lysine and arginine, without affecting the protein quality. When compared to the raw seed sample, all the hydrothermal processing increased the total (TS) and digestible (DS) starch content (351–361 and 303–315 g kg−1, respectively) and decreased the resistant starch (RS) content (46.1–48.1 g kg−1) significantly (P<0.05). The in vitro starch digestion rate was also measured in the freshly processed seed samples, and the values of HI and GI were comparable to that of similarly processed legumes such as moth bean and black gram.