Effect of soaking and cooking on selected soybean variety for preparation of fibrinolytic douchi.

摘要

During preparation of douchi, a traditional Chinese fermented soy product, soaking and cooking pretreatments directly influence nutrient contents and product quality. This study investigated contents of soluble protein, soluble sugars and soluble solids, hardness and digestibility of pretreated soybeans after exposure to different soaking and cooking conditions. Effects of soaking and cooking on fibrinolytic activity and amino N content of douchi were also studied. The soybean var. Longxiaolidou1 was cooked at 115 degrees C for 10, 20 or 30 min after soaking for up to 10 h. Solid loss, including soluble protein, increased significantly with increases in soaking time. Hardness decreased significantly after increases in cooking time rather than increases in soaking time. Digestibility rate of cooked soybeans reached its optimum after 3 h soaking and 20 min of cooking. Fibrinolytic activity was highest after 1 h soaking and 30 min cooking. Amino N content was highest after 20 min cooking and decreased with soaking time. Based on these results, soaking soybeans for 3 h and cooking for 20 min at 115 degrees C were optimal with respect to nutrient content and quality of douchi.