Effect of irradiation (γ-rays) on the physical, sensory and nutritive properties of bean seeds

Abstract

Dry beans (Phaseolus vulgaris L. cv. Carioca 80) which had been stored for one year at 12°C one year at 12°C and 50% RH were submitted to gamma irradiation (500 and 1000 krad). Compared to nonirradiated bean, irradiation with 500 krad increased hydration capacity and velocity and reduced the cooking time to 1/3. A decrease in natural cooked bean odor and appearence of off-odor, was noticed. The hardness of irradiated beans was significantly lower than nonirradiated at 10 and 20 min of cooking in pressure cooker. There was no difference between the two after 30 min cooking. No differences were detected between the two levels of irradiation. Irradiation with 1000 krad did not affect the protein efficiency ratio but it did affect negatively the digestibility, the biological value and the net protein utilization. When methionine was added (2% of the protein) to the diet, the negative effects of irradiation were eliminated. Diet consumption and body weight gain improved for the rats fed on diet containing irradiated beans supplemented with methionine, when compared with rats fed the diet containing nonirradiated beans equally supplemented with methionine.