Chemical composition, antinutritional factors and effect of cooking on nutritional quality of rice bean [Vigna umbellata (Thunb; Ohwi and Ohashi)

Abstract

The mature seeds of four cultivars of rice bean [Vigna umbellata (Thunb; Ohwi and Ohashi)] were analysed for some nutritional and antinutritional factors. The cultivars showed little variation in their chemical composition. On a dry matter basis, the percentage of crude protein varied from 16.9 to 18; crude fat 0.46 to 0.52, crude fibre 6.3 to 7.5, total soluble sugar 4.9 to 5.6, starch 52.2 to 55 and ash 4.2 to 4.4. The amounts (mg/100 g) of calcium ranged from 280 to 325, sodium 43 to 52, potassium 171 to 210, phosphorus 216 to 275 and iron 6 to 7, respectively. The cultivars had trypsin inhibiting activities (TIA) of 2456 to 2534 TIU g−1 phytic acid 1976 to 2170 mg per 100 g and tannins 513 to 572 mg per 100 g, respectively. Two cooking treatments, namely, 15 min pressure cooking (15 MPC) and 50 min boiling (50 MB) showed a considerable decrease in antinutritional factors.