The term 'food-grade', is applied to varieties intended for production of soyfoods. Although any soybean variety can be used to make soyfoods, certain varieties are preferred. In the production of soymilk and tofu, high soluble protein leads to higher yield of food product, i.e., more weight of product per pound of soybeans. Ability of tofu to form a satisfactory gel is also believed to be related to the protein content of the soybeans. Soymilk protein content reflects the concentration of soluble protein in the soybean grain.
High values are desirable for both measurements.
As the North American soybean industry developed, the U.S. Department of Agriculture, from 1936 to 1941, named and released several Asian introductions as food-grade varieties. Two of these varieties, 'Willomi' and 'Wolverine' were known to have been produced in Japan and used for making tofu there.