NUTRITIONAL COMPOSITION AND ANTINUTRITIONAL FACTORS OF LITTLE-KNOWN SPECIES OF VIGNA

Abstract

The seeds of Vigna trilobata, V. radiata var. sublobata, V. umbellata, V. unguiculata subsp. cylindrica, V. aconitifolia, V. vexillata and V. bourneae were collected from different geographical regions in Western Ghats, Tamil Nadu. They were analyzed for their proximate and mineral composition, vitamins (niacin and ascorbic acids), fatty acid profiles, amino acid profiles of total seed proteins, in vitro protein digestibility (IVPD) and certain antinutritional factors. The crude protein ranged from 18.24 to 26.12%, crude lipid 3.18 to 6.48%, total dietary fibre 3.42 to 7.48%, ash 3.10 to 4.12% and carbohydrates 59.44 to 72.06%. Energy values of the seeds were 1584.87 – 1644.34 kJ100g-1DM, which were comparable to those of other legumes. The fatty acid profiles of all the species of Vigna revealed that the seed lipids contained higher concentrations of palmitic, oleic, linoleic and linolenic acids. The essential amino acid profiles of total seed proteins compared favourably with FAO/WHO (1991) requirements, except that there were deficiencies of sulphur containing amino acids in all the species of Vigna. The IVPD of the different Vigna species ranged from 70.38 to 79.12%. Antinutritional substances like total free phenolics, tannins, L-DOPA (3, 4-dihydroxyphenylalanine), phytic acid, hydrogen cynide, trypsin inhibitor activity, oligosaccharides and phytohaemagglutinating activity were also investigated. The antinutritional factors that were detected were thought to have little nutritional significance if the beans are properly processed.