Inactivation of Trypsin-inhibitor and Unsolubilization of Protein by Parching of Soybean Flour

Abstract

Soybean protein is not easily digested because of its coexisting trypsin-inhibitor (TI). Practically, in cooking, soybean is usually boiled, steamed or parched in order to inactivate TI. In the previous report, the author described that the soybean protein is easily digested when soybean is parched before crush, but not when it is parched after crush. This report describes the change of TI activity when soybean was parched at 150°C. The TI activity of soybean flour after parching was extremely decreased to the degree as that of boiled soybean. However, the TI activity of parched soybean after crush was maintained to the same level as that of raw soybean.