Heat Inactivation of Trypsin Inhibitor in Fresh Green Soybeans and Physiological Responses of Rats Fed the Beans

Fresh green soybeans were heated in boiling water for up to 9 min to destroy trypsin inhibitor (TI) activity. The beans were tested for TI activity and fed to rats to ascertain physiological responses. TI activity was destroyed rapidly; after 1 min, 62.4% was destroyed and after 3 min, 90%. As expected, raw (unheated) beans had an adverse effect on weight gain; however, rats receiving beans from all heating durations exhibited less gain than rats fed casein. Protein efficiency ratio (PER) was 1.20 when rats were fed raw beans. However, PER increased with time of heating such that at 9 min PER was 1.90. Pancreatic hypertrophy occurred only in rats fed raw beans. The liver weighed less in rats fed raw beans than in rats fed heated beans or casein. Lipid content of liver from rats fed raw beans was greater than that from rats fed heated beans or casein. The protein content of liver from rats fed raw beans was lower than that from rats fed heated beans or casein.