Most of the world's soybean production is processed ("crushed") to produce both oil, chiefly for human consumption, and meal, an important source of protein for livestock. A small portion of the crop, however, is used to produce traditional soyfoods, such as soymilk, tofu, miso, tempeh, eda mame, and natto. Tofu, or soybean curd, is one of the most important of these foods. Produced by coagulation of soymilk, it is a major source of protein in the diet, particular in the East Asian countries. 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. Seed (grain) characters believed to be important for production of tofu and other soyfoods include high content of protein, especially soluble protein, large seed weight, acceptable color, and high sugar content of these characteristics, high protein content is probably the most important. 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. Also, the protein content of the soybeans is strongly related to the protein content (and therefore the nutritional quality) of the food product.
Soymilk solids content is a strong indicator of tofu yield (the number of pounds of tofu that can be obtained from a pound of soybeans). Soymilk protein content reflects the concentration of soluble protein in the soybean grain. High values are desirable for both measurements.
Identification of varieties for particular food uses was a feature of traditional soybean production in its Asian homeland (China, Japan, and Korea). 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. None of the U.S.D.A. releases was ever widely grown in the U.S. Later, varieties such as 'Hawkeye' (released in 1947), 'Kanrich' (1956), and 'Beeson' (1968) were used for production of soyfoods, particularly tofu. Interestingly, Hawkeye and Beeson were originally selected and widely grown as grain-type varieties; their suitability for tofu production was discovered only after their release.
Numerous food-grade soybean varieties are currently on the market, including varieties developed by at least five state experiment stations, several private companies, and Agriculture and Agri-Food Canada. The varieties 'Beeson 801' and 'Vinton 811', which possess resistance to Phytophthora rot [caused by Phytophthora sojae (Kaufmann and Gerdemann)], are the most widely grown foodgrade varieties in Ohio. Ohio FG1 and Ohio FG2 were developed to replace 'Beeson 80' and 'Vinton 81.'