Nutritional and anti-nutritional composition of velvet bean: an under-utilized food legume in south India

Four accessions of the under-utilized legume, velvet bean (Mucuna pruriens var. utilis (Wall. ex Wight) Bak. ex Burck), collected from three different locations of Western Ghats, South India were analysed for proximate composition, mineral profiles, the protein fractions, amino acid profiles of total seed protein, in vitro protein digestibility and certain anti-nutritional factors to determine their potential as an alternative source to alleviate protein-energy-malnutrition among the people of South India. The major findings of the study were as follows: crude protein ranged from 20.2-29.3%, crude lipid 6.3-7.4%, total dietary fibre 8.7-10.5%, ash 3.3-5.5% and carbohydrates 49.9-61.2%. The energy level of the seed (1562-1597 kJ 100 g-1 DM) was comparable with commonly consumed Indian pulses. Mineral profiles, viz. sodium, potassium, calcium, magnesium, phosphorus, iron, copper, zinc and manganese ranged from 43.1-150.1, 778.1-1846.0, 393.4-717.7, 174.9-387.6, 98.4-592.1, 10.8-15.0, 0.9-2.2, 5.0-10.9, 3.9-4.3 mg 100(-1) seed flour, respectively. The data on seed protein fractions revealed that the globulins constitute the major bulk of the seed protein as in most legumes. Profiles of amino acids of total seed proteins detected in the present study revealed that they contain relatively higher levels of all essential amino acids except threonine, leucine and lysine in black-coloured seed coat accessions and phenylalanine and tyrosine in white-coloured seed coat accession compared with the FAO/WHO (1991) requirement pattern. The in vitro protein digestibility of the legumes under study ranged from 72.4-76.9%. Anti-nutritional substances like total free phenolics, tannins, L-DOPA, trypsin inhibitor activity and phytohaemagglutinating activity also were investigated. The detected anti-nutritional factors probably have little nutritional significance if the beans are properly processed.