Effect of high-pressure saturated steam treatment on the flavor, browning and solubility of micro soy flour

The aim of this study is to clarify whether three problems in heat treatment of soy flour (improve of flavor and taste, excessive browning and maintaining of solubility) can be solved by combining soybean pulverization and heat treatment using autoclave. We obtained to raw micro soy flour (RMS) by cross jet mill. We heated RMS by autoclave at 117-126℃ for 0-60 min, and we measured Brix value, browning, and unpleasant. In the results indicated that optimum heat treatment existed some condition. As a result of nutritional analysis, heat treatment micro soy flour (HMS) (120℃ for 10 min) had higher moisture and lipid content compared to RMS, and the carbohydrate content was lower. Next, we measured color tone of soy flour with a color difference meter. In this result, heat treatment micro soy flour (HMS) (120℃ for 10 min) was browning compared to RMS, but it was not browning compared to Kinako. The HMS was dissolved in water by combination of boiling and strong mixing. Moreover, this powder formed tofu curd by coagulant agent. Finally, a sampling test was conducted on RMS and HMS (120℃ for 10 min). Off-flavor and bitter taste in HMS was decreased than in RMS. On the other hand, astringent taste was not significantly affected in heating. Color in HMS was slightly browned than in RMS. Sweet taste and texture was slightly decreased than in RMS. In conclusion, combining soybean pulverization and heat treatment using autoclave can improve grassy odor, bitter taste, excessive browning and solubility in heat treatment of soy flour.