Germination reduces black gram (Vigna mungo) and mung bean (Vigna radiata) vicilin immunoreactivity

Abstract

Beans are often processed before consumption, and germination is one such processing method. The objective of this study was to investigate the effect of germination on the immunoreactivity of black gram (BG) and mung bean (MB) vicilins. BG and MB seeds were germinated for ten days. Immunoreactivity of the seed proteins was analyzed by enzyme-linked immunosorbent assay (ELISA) and Western blot using rabbit anti-whole BG soluble protein antiserum and rabbit anti-BG vicilin polyclonal antibodies. Electrophoretic analysis of sprouted BG and MB soluble proteins exhibited a gradual decrease in the 40–60 kDa polypeptides with a concomitant increase in the 9–26 kDa polypeptides. Non-germinated MB registered 68% immunoreactivity as compared to the corresponding BG control designated as 100%. Upon germination, the vicilin immunoreactivity of BG remained stable for eight days, while that of MB decreased by 41% on day one. On the tenth day, germinated BG and MB vicilins exhibited 55% and 74% reduction in immunoreactivity, respectively. Western blot and ELISA results collectively showed that BG vicilin was more resistant than MB vicilin to proteolysis during germination. Vicilin degradation resulted in the appearance of an immunoreactive 23 kDa polypeptide. In conclusion, germination significantly decreased, not eliminated, immunoreactivity of BG, and MB vicilins.