Abstract
Yogurt-like food was prepared by use of defatted soybean flour in order to decrease the beany flavor as well as soybean itself as the control. Microwave heating used for preparation of soymilk was effective for protein extraction from"go", soy slurry or defatted soybean flour suspension, in comparison with the conventional heating method by boiling water. Lipoxygenase in soymilk was inactivated at ca. 80°C by either heating method. Trypsin inhibitor activity in soymilk was more decreased by the conventional heating than the microwave heating, and the remaining activity was still nearly 50%. After fermentation of soymilk with a lactic acid bacterium, Streptococcus thermophilus, the trypsin inhibitor activity further decreased to about 30%. For the preparation of more palatable yogurt-like food, soymilk mixed with an equal volume of commercial milk was fermented. The yogurt-like food thus obtained, contained mainly lactic acid as well as citric acid and α-ketoglutaric acid, whose organic acids were detected by HPLC. This food made by using defatted soybean flour was considered as acceptable as food from the sensory evaluation by students panelists, who admitted the improvement of attributes such as beany flavor, taste and overall preference for this food.
