Carbohydrate composition of low dose radiation-processed legumes and reduction in flatulence factors

The effects of low dose γ-radiation processing, for insect disinfestation, on functionally important sugars, were investigated in commonly used legumes i.e. mung, Bengal gram, horse beans (val), horse gram, cowpeas and rajma. The separation profiles of legume carbohydrates were qualitatively comparable; distinct legume-specific quantitative changes were observed. The main flatulence-producing raffinose family oligosaccharides (RFO), stachyose and verbascose, which constituted 55–65% of soluble carbohydrates in these legumes, were degraded at different rates during 0–4 days of germination, with concomitant accumulation of easily metabolizable sucrose and reducing sugars. Radiation processing enhanced this in a legume-specific manner. Subtle differences in degradations of these oligosaccharides, between control and irradiated samples (0.25 and 0.75 kGy) were observed in the dry seeds of Bengal gram, horse beans (val), and cow peas; these were highly significant in mung and horse gram on the second day of germination and no change was noticed in rajma. Degradation of flatulence factors reflected an accumulation of sucrose in Bengal gram, cow peas and rajma rather than reducing sugars, which were more prominent in mung and horse gram. These results conclusively indicate that radiation processing of the six legumes, at disinfestation dose (0.25 kGy) and germination (0–2 days), results in rapid degradation of flatulence factors without affecting their sprout lengths; this improves their nutritional acceptability, though subtle varietal differences are noticed. At higher dose (0.75kGy), significant reductions in their sprout lengths compared to the control were noticed; however, their sensory attributes were not altered.