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.