Effect of thermal processing on protein solubility of green gram (Phaseolus aureus) legume cultivars

Green gram legume cultivars were analyzed for their protein solubility profile by fractionation in the raw form and also after heat processing. The results indicated that globulin fractions, which are present in major amounts that ranged from 79.5 to 85.4 % significantly decreased after the heat treatment. This decrease was accompanied by a significant increase in the glutelin-3 fractions. The prolamine contents did not vary considerably after processing. The protein and non-protein nitrogen contents ranged from 22.6 to 26.2 % and 2.3 to 2.7 % in the legume cultivars, respectively. The antinutritional factors like total polyphenol and phytic phosphorous were also determined. The accumulation of polyphenols was in the seed coat portion of the legume where as that of phytic phosphorus was in the cotyledons. SDS - PAGE profiles of all the three green gram cultivars had five major polypeptides (molecular weight 15, 18, 20, 45 and 60 kDa) in the total protein composition. Wide variation in electrophoresis pattern was observed after heat processing. Thermal treatment increased the insoluble protein fractions and eliminated the minor polypeptide bands below 14.3 kDa in the green gram cultivars.