Influence of Processing Conditions on Isoflavones Content of Soybean Products

摘要

The effects of processing conditions on the changes in isoflavones content of black soymilk and soymilk film (yuba)were investigated. When black soybeans were soaked in water at 30 and 50 °C for various periods of time, the contents of daidzein and genistein increased with an increase of the soaking time while daidzin and genistin decreased. There was no significant difference (P < 0.05) in the contents of isoflavones in black soybean under soaking at 30 °C for 12 h and at 50 °C for 6 h. The amounts of isoflavones in black soybean changed markedly under soaking at 20-60 °C for 8 h. The change in the contents of isoflavones in black soybean during soaking was related to its β-glucosidases activity. The effect of soaking temperature in β-glucosidases activity of black soybean was in the order of 50 > 40 > 60 > 30 > 20 °C. The contents of daidzein and genistein in Yuba prepared by soaking soybeans at 50 °C for 6 h were about 2.5 times of that prepared by soaking soybeans at 30 °C for 12 h. Thus, changing the processing conditions can increase the contents of isoflavone aglycones in soybean products.