Rice bean: nutritional vibrant bean of Himalayan belt (North East India)

Abstract

Purpose The purpose of this paper was to analyse the present status of the information available on rice bean [Vigna umbellata (Thunb.)] cultivars with respect to its nutritional and functional characteristics. It is one of the non-conventional and under-utilized beans of South and Southeast Asia. In northeastern regions of India, it is an important crop for shifting cultivation or kitchen garden which is consumed as vegetable (tender pod) and pulse. The information gaps filling could be useful for several work proposals and for consumers and cultivators to know the nutritional strength and varied usability of the grain which in-turn can help in its commercialization. Design/methodology/approach The approach to information collection was emphasized on nutritional strength of the grain compared to other beans of Vigna family and the varied usability among the rice bean varieties of the Himalayan Belt. Findings The average carbohydrate, protein, fat, crude fibre and ash content of 75 genotypes of rice bean was found 59.96 ± 2.81, 20.78 ± 2.65, 1.74 ± 1.42, 5.07 ± 1.17 and 4.44 ± 1.03 per cent, respectively. It has high quality protein with all essential amino acid in balance manner. Among the minerals, it contains calcium, iron, zinc and potassium with high bio-availability of calcium (59.8 ± 0.3 per cent). The factors such as flatulence producing saccharides, trypsin inhibitors, polyphenols, phytic acid, saponin and tannins of rice bean were reported to be in the range of 3.28-5.87 per cent, 55.12-163.98 TIU/g, 0.58-1.82 1.88-8.17, 1.2-3.1 and 0.24-1.55 per cent, respectively. The toxic compounds such as hydrogen cyanide (0.09 mg/100 g) and L-3, 4-dihydroxyphenylalanine (0.36 mg/100 g) is lowest in rice bean. The nutritional advantages of rice bean over the other beans of Vigna family were required to emphasize to induce interest among the researchers, producers and consumers. Research limitations/implications In view of the recommended daily requirements with respect of amino acids, vitamin-B and minerals, rice bean could be a major component of the diet to fulfill them. However, the scanty information available on nutritional and functional components of rice bean varieties grown in northeastern India calls for the gap filing research to explore full potential of the bean. Originality/value The information about differences among the northeastern varieties of rice bean available on nutritional functional components essentially required the updating of research data to explore full potential and utility of the bean.