Soybeans: Cows Without Bones Back to Map Page NE China Soybeans are believed to be native to northeastern China, where domestication may have occurred over 3,000 years ago. There, soybeans are referred to as "poor man's meat" and "cows without bones," because they have more protein and fewer carbohydrates per 100 grams of edible portion than most other legumes and can be used as a partial substitute for animal protein. Although China now produces only 10% of the world's soybeans, the soybean has been the cornerstone of eastern Asian nutrition for centuries. Soybeans were introduced to North America in 1765, but they did not gain popularity and were not commercially planted until 1920. Eventually, however, because of favorable growing conditions in the Midwest, the United States became the world's leading producer of soybeans. Today, over half of U.S. soybeans are exported. The balance are used mainly for animal feed and processing soybean oil, which is consumed as margarine, shortening, mayonnaise, and salad oil and also used in plastic, paints, and adhesives. The soybean, Glycine max, is in the Fabaceae, a large family of legumes composed of dicots and represented by over 650 genera and 16,400 species. Sometimes also called Leguminosae, this family name specifically refers to the type of dry fruit, or legume, produced by thousands of members of this family. Economically valuable food genera within the Fabaceae include the lima bean and common bean (black, green, wax; Phaseolus sp.), lentils (Lens culinaris), peas (Pisum sativum), fava beans (Vicia faba), and chick-peas (Cicer arietinum). Most members of Fabaceae have root nodules with nitrogen-fixing bacteria (Rhizobium sp.). This mutualism enables legumes to grow on relatively poor soils and to enrich nitrogen-poor soils in the process (nitrogen is a limiting nutrient for terrestrial plants).   cross section of legume root nodule cells filled with Rhizobium sp. Glycine max.            Soy milk Soybeans cannot be consumed raw because they contain a digestive enzyme called trypsin, which interferes with protein digestion in humans. Heat, however, denatures the enzyme, so cooking renders soybeans safe for consumption. Soybeans can be boiled, salted, roasted, or made into a paste or curd. Traditional soy sauce is made by fermenting soybeans in brine, although many American brands of soy sauce are synthetic. Soy milk is made by soaking the beans in water and pureeing them, adding heat, and then filtering. Soy milk has become a popular alternative to animal milk, especially as a nondairy substitute for lactose-intolerant individuals. It is also gaining popularity as an infant formula. The particulate material left after filtering the soy milk is a soy product called "okara," which has the consistency of cottage cheese. Tofu, another product made from soy milk, is very nutritious and easily digestible. Although sometimes criticized for its blandness, tofu soaks up the flavors of other foods it is mixed with, so is quite versatile for cooking. Although the Japanese consume more than 5 pounds of tofu per person per day, Americans need more innovative products to capture their interest. Therefore, most recently appearing on the shelves of grocery stores are soy-based bacon, hot dogs, ice cream, and cheese. Although soybeans are an important source of nutrients, they lack vitamin C. People living in areas that are traditionally dependent on soybeans have overcome this potential deficiency by eating the soy sprouts, which are rich in vitamin C and usually served in salads. Composition of food legumes based on a 100-g edible portion Current research indicates that soy contains estrogen-like compounds called phytoestrogens (plant estrogens). Isoflavonoids specifically are being isolated and marketed as an alternative to hormone replacement therapy for women, as with the soybean's relative, red clover, a legume scientifically known as Trifolium pratense [for more information, see Plant Estrogens"]. Additional research supports the ability of soy to lower blood cholesterol. It is important to keep in mind, however, that different processing methods may result in varying amounts of nutrients, amino acids, and actual soy in the final product. But any way you get it, the Food and Drug Administration (FDA) recommends eating about 25 grams of soy protein per day. References, Websites, and Further Reading Gorman, Christine. 1999. The joy of soy. Time, June 7. Heywood, V.H. 1993. Flowering plants of the world. New York: Oxford University Press. Levetin, Estelle, and Karen McMahon. 1999. Plants and society, 2d ed. New York: McGraw-Hill Companies, pp. 214-16. Simpson, B.B., and Molly C. Ogorzaly. 2001. Economic botany: Plants in our world, 3d ed. New York: McGraw-Hill Companies. Soy Protein Council http://www.spcouncil.org/ Soybean and Alfalfa Research Laboratory of the USDA-ARS (United States Department of Agriculture-Agricultural Research Service) http://bldg6.arsusda.gov/pberkum/Public/sarl/welcome.html Soybean," Microsoft® Encarta® Online Encyclopedia 2000. © 1997-2000, Microsoft Corporation. http://encarta.msn.com StratSoy at the University of Illinois providing soybean production statistics, nutrition, and market information http://www.ag.uiuc.edu/~stratsoy/new/ United Soybean Board http://www.unitedsoybean.org/ Related Reading in Stern, Introductory Plant Biology, 8th Edition Chapter 2: The Nature of Life Carbohydrates, pp. 22-23 Proteins, p. 24 Enzymes, p. 26 Chapter 5: Roots and Soils Root Nodules, including Figure 5.17, p. 75 Chapter 8: Flowers, Fruits, and Seeds Differences Between Dicots and Monocots, including Table 8.1, pp. 129-30 Fruits, including legumes and dry fruits, pp. 132-39 Seeds: Structure, Germination, including Figure 8.28, pp. 143-45 Chapter 14: Plant Propagation and Biotechnology Other Applications of Genetic Engineering, including genetically altered soybeans, p. 249 Chapter 24: Flowering Plants and Civilization