The defatted soybeans used for soy sauce have a higher protein content, which is more conducive to the decomposition of the quartz-making and microbial enzymes, and their protein hydrolysis is more thorough, with a high rate of total nitrogen utilization, which is conducive to the formation of the fresh flavor of the soy sauce. Of course, due to the reduction of lipids, the flavor of soy sauce brewed with defatted soybeans is slightly insufficient compared to that of the original soybeans, but the reduction of fats and oils can prevent the rancidity of soy sauce.