The soybean (U.S.) or soya bean (UK) (Glycine max) is a species of legume native to East Asia. The plant is classed as an oilseed rather than a pulse.
Fat-free (defatted) soybean meal is a primary, low-cost, source of protein for animal feeds and most prepackaged meals; soy vegetable oil is another valuable product of processing the soybean crop. For example, soybean products such as textured vegetable protein (TVP) are important ingredients in many meat and dairy analogues.
Traditional nonfermented food uses of soybeans include soymilk, and from the latter tofu and tofu skin. Fermented foods include soy sauce, fermented bean paste, natto, and tempeh, among others. The oil is used in many industrial applications. The main producers of soy are the United States (32%), Brazil (28%), Argentina (21%), China (7%) and India (4%). The beans contain significant amounts of phytic acid, alpha-Linolenic acid, and the isoflavones genistein and daidzein.
Soybeans can produce at least twice as much protein per acre as any other major vegetable or grain crop, 5 to 10 times more protein per acre than land set aside for grazing animals to make milk, and up to 15 times more protein per acre than land set aside for meat production.
The plant is sometimes referred to as greater bean (Chinese dadou and Japanese daizu). In Vietnam, the plant is called dau tuong or dau nanh. Both immature soybean and its dish are called edamame in Japan, but in English, edamame refers only to a specific dish. The English word "soy" is derived from the Japanese pronunciation of shoyu, the Japanese word for soya sauce; "soya" comes from the Dutch adaptation of the same word.
Chemical composition of the seed
Together, oil and protein content account for about 60% of dry soybeans by weight; protein at 40% and oil at 20%. The remainder consists of 35% carbohydrate and about 5% ash. Soybean cultivars comprise approximately 8% seed coat or hull, 90% cotyledons and 2% hypocotyl axis or germ.
Most soy protein is a relatively heat-stable storage protein. This heat stability enables soy food products requiring high temperature cooking, such as tofu, soy milk and textured vegetable protein (soy flour) to be made.
Since soluble soy carbohydrates are found in the whey and are broken down during fermentation, soy concentrate, soy protein isolates, tofu, soy sauce, and sprouted soy beans are without flatus activity. On the other hand, there may be some beneficial effects to ingesting oligosaccharides such as raffinose and stachyose, namely, encouraging indigenous bifidobacteria in the colon against putrefactive bacteria.
The insoluble carbohydrates in soybeans consist of the complex polysaccharides cellulose, hemicellulose, and pectin. The majority of soybean carbohydrates can be classed as belonging to dietary fiber.
Soy protein products can be good substitutes for animal products because, unlike some other beans, soy offers a 'complete' protein profile. Soy protein products can replace animal-based foods—which also have complete proteins but tend to contain more fat, especially saturated fat—without requiring major adjustments elsewhere in the diet. However, as with many dietary health claims, there are opposing viewpoints on the health benefits of soybeans.
In contradiction to well known benefits of isoflavones, genistein acts as an oxidant (stimulating nitrate synthesis), and blocks formation of new blood vessels (antiangiogenic effect). Some studies show that genistein acts as inhibitor of substances that regulate cell division and cell survival (growth factors).
A review of the available studies by the United States Health and Human Services Agency for Healthcare Research and Quality (AHRQ) found little evidence of substantial health improvements and no adverse effects, but also noted that there was no long-term safety data on estrogenic effects from soy consumption.
Reference : http://en.wikipedia.org/wiki/Soybean