| Great Northern bean (Phaseolus vulgaris L.) drum dried flours at native pH of 6.54, pH 6 and 7 showed reduced activities of trypsin inhibitor (23%-30%), $alpha$-amylase inhibitor (non-detectable levels), hemagglutinating titer (98.7%-99.8%), and nitrogen solubility. Electrophoretic analyses showed a slight modification of the native bean proteins, and the presence of at least four trypsin inhibitors.;The study of the effect of 2.5-20 kGy irradiation doses on Great Northern beans showed essentially no modification of the electrophoretic mobility of the storage proteins or the trypsin inhibitors. Nitrogen solubility and hemagglutinating activity were essentially unchanged. With the 20 kGy dose, decrease in $alpha$-amylase inhibitor activity (5.7%-11%), decrease reactive/available lysine content (9.5%-18%), and decrease cooking time (58.5%) of the irradiated beans after 11 months of storage were observed. Taste panel results indicated that the control and 20 kGy irradiated bean were significantly different at 5% level. At 20 kGy dose, the beans developed a partially water soluble brown color.;Gamma irradiation doses at 2.5 to 20 kGy in bean starch apparently caused an induction to kidney bean or shamrock shaped starch granule and surface fissures. The approximate molecular weights determined on gel filtration chromatography of control (0 kGy) were: amylopectin $>$ 2 $times$ 10$sp6$ d, and amylose 2 $times$ 10$sp5$ d. The amylopectin peak area and molecular weight of both amylopectin and amylose were observed to decrease as the irradiation dose was increased. Increasing the irradiation dose caused an increase in the reducing value, free and total acidity, and starch solubility, suggesting the formation of lower molecular weight dextrins and acid groups. An apparent increase in gelatinization temperature (1.4 C), and enthalpy (0.7 cal/g) suggested a less organized irradiated (20 kGy) granule starch. ESR spectra showed the formation of stable radicals. X-ray diffraction patterns of bean starch revealed no change in crystallinity. Both, control and irradiated samples showed the A-type pattern structure. |
