Effects of dehulling, cooking and storage conditions on protein quality and digestibility of soybeans

Soybeans were dehulled, stored under two environmental conditions [25 degrees C/75% R.H. (Env. 1) and 38 degrees C/90% R.H. (Env.2)], optimally cooked and assayed for trypsin inhibitor and protein quality with laboratory rats. Dehulling did not significantly affect protein quality (PER and NPR) and protein digestibility of raw and cooked soybeans. Raw soybeans diets were significantly poorer in protein quality and digestibility when compared with cooked counterparts. PER values of dehulled-cooked soybean diets decreased significantly (P<0.05) as seeds were stored for up to 3 months under either environment. There were no significant differences in PER values due to storage during the period from 3 to 6 months. PER values for whole-cooked soybean diets exhibited a significant decline only when stored for 6 months under Env. 2.