Jilin reader Ms. Xu asked: Recently, my mother sent a small video, which mentioned that the "defatted soybean" used to make soy sauce is soybean residue, pig feed, just like "chewing leftover bagasse" or food ingredients "leftovers", so soy sauce labeled with defatted soybean can not be bought. Does the video make sense?
Dr. Zhong Kai, Director of Kexin Food and Nutrition Information Exchange Center, answered: Fermented soy sauce with defatted soybeans was first created by the Japanese in 1913, and has matured after hundreds of years of development, and was introduced in China in the 1950s to 1960s. Defatted soybeans are obtained after the removal of fat from soybeans, commonly known as soybean meal or soybean cake. It can indeed be used as feed, but it can also be used in the food industry, such as fermented soy sauce, or made into "soy protein isolate" for meat products, baked goods, vegetable protein drinks and so on. However, different uses have different requirements, food with food grade, feed with feed grade, two irrelevant. The fat in soybeans (mainly soybean oil) accounts for only 15% to 20%, so soybean meal is the protagonist. The main reason for fermenting soy sauce with defatted soybeans is that it is low in fat and high in protein, and the fermentation efficiency is higher, so the cost per unit of product can be reduced.
The main function of soy sauce is to enhance the freshness and color, of which the freshness mainly depends on the amino acids produced by the decomposition of soybean protein, and the color mainly depends on the "Maillard products" obtained by the reaction of amino acids and sugars (dark soy sauce mainly relies on caramel color). Fat is rarely involved in the fermentation process, and most of it is discarded with the sauce residue.
Of course, soy sauce made with whole and defatted soybeans is definitely different in flavor, because the fat in soybeans will oxidize and degrade during the fermentation process, producing some volatile flavor substances. These tastes are not necessarily good tastes, but because they are "traditional tastes", some people will find them more authentic. In short, different processes will give products different characteristics, consumers can choose by their own tastes.
