The soybean (U.S.) or soya bean (UK) (Glycine max) is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses. 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 product of processing the soybean crop. For example, soybean products such as textured vegetable protein (TVP) are ingredients in many meat and dairy analogues. Soybeans produce significantly more protein per acre than most other uses of land.
Traditional nonfermented food uses of soybeans include soy milk, 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 (35%), Brazil (27%), Argentina (19%), China (6%) and India (4%). The beans contain significant amounts of phytic acid, alpha-linolenic acid, and the isoflavones genistein and daidzein.
The plant is sometimes referred to as greater bean ( Chinese dàdòu and Japanese daizu). 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 shōyu , the Japanese word for soya sauce; "soya" comes from the Dutch adaptation of the same word.
Varieties of soybeans are used for many purposes.
The genus name Glycine was originally introduced by Carl Linnaeus (1737) in his first edition of Genera Plantarum. The word glycine is derived from the Greek - glykys (sweet) and likely refers to the sweetness of the pear-shaped (apios in Greek) edible tubers produced by the native North American twining or climbing herbaceous legume, Glycine apios, now known as Apios americana. The cultivated soybean first appeared in Species Plantarum, by Linnaeus, under the name Phaseolus max L. The combination Glycine max (L.) Merr., as proposed by Merrill in 1917, has become the valid name for this useful plant.
The genus Glycine Willd. is divided into two subgenera, Glycine and Soja. The subgenus Soja (Moench) F.J. Herm. includes the cultivated soybean, Glycine max (L.) Merr., and the wild soybean, Glycine soja Sieb. & Zucc. Both species are annuals. Glycine soja is the wild ancestor of Glycine max, and grows wild in China, Japan, Korea, Taiwan and Russia. The subgenus Glycine consists of at least 16 wild perennial species: for example, Glycine canescens F.J. Herm. and G. tomentella Hayata, both found in Australia and Papua New Guinea.
Like some other crops of long domestication, the relationship of the modern soybean to wild-growing species can no longer be traced with any degree of certainty.
Description and physical characteristics
Soy varies in growth and habit. The height of the plant varies from below 20 cm (7.9 in) up to 2 metres (6.6 ft).
The pods, stems, and leaves are covered with fine brown or gray hairs. The leaves are trifoliolate, having three to four leaflets per leaf, and the leaflets are 6–15 cm (2.4–5.9 in) long and 2–7 cm (0.79–2.8 in) broad. The leaves fall before the seeds are mature. The inconspicuous, self-fertile flowers are borne in the axil of the
leaf and are white, pink or purple.
Small, purple soybean flowers
The fruit is a hairy pod that grows in clusters of three to five, each pod is 3–8 cm long (1–3 in) and usually
contains two to four (rarely more) seeds 5–11 mm in diameter.
Soybeans occur in various sizes, and in many hull or seed coat colors, including black, brown, blue, yellow, green and mottled. The hull of the mature bean is hard, water resistant, and protects the cotyledon and hypocotyl (or "germ") from damage. If the seed coat is cracked, the seed will not germinate. The scar, visible on the seed coat, is called the hilum (colors include black, brown, buff, gray and yellow) and at one end of the hilum is the micropyle, or small opening in the seed coat which can allow the absorption of water for sprouting.
Remarkably, seeds such as soybeans containing very high levels of protein can undergo desiccation, yet survive and revive after water absorption. A. Carl Leopold, son of Aldo Leopold, began studying this capability at the Boyce Thompson Institute for Plant Research at Cornell University in the mid 1980s. He found soybeans and corn to have a range of soluble carbohydrates protecting the seed's cell viability.
Patents were awarded to him in the early 1990s on techniques for protecting "biological membranes" and proteins in the dry state. Compare to tardigrades.
Chemical composition of the seed
Soybean, mature seeds, rawNutritional value per 100 g (3.5 oz)
Energy 1,866 kJ (446 kcal)
Carbohydrates 30.16 g
- Sugars 7.33 g
- Dietary fiber 9.3 g
Fat 19.94 g
- saturated 2.884 g
- monounsaturated 4.404 g
- polyunsaturated 11.255 g
Protein 36.49 g
- Tryptophan 0.591 g
- Threonine 1.766 g
- Isoleucine 1.971 g
- Leucine 3.309 g
- Lysine 2.706 g
- Methionine 0.547 g
- Cystine 0.655 g
- Phenylalanine 2.122 g
- Tyrosine 1.539 g
- Valine 2.029 g
- Arginine 3.153 g
- Histidine 1.097 g
- Alanine 1.915 g
- Aspartic acid 5.112 g
- Glutamic acid 7.874 g
- Glycine 1.880 g
- Proline 2.379 g
- Serine 2.357 g
Water 8.54 g
Vitamin A equiv. 1 μg (0%)
Vitamin B6 0.377 mg (29%)
Vitamin B12 0 μg (0%)
Vitamin C 6.0 mg (10%)
Vitamin K 47 μg (45%)
Calcium 277 mg (28%)
Iron 15.70 mg (126%)
Magnesium 280 mg (76%)
Phosphorus 704 mg (101%)
Potassium 1797 mg (38%)
Sodium 2 mg (0%)
Zinc 4.89 mg (49%)
Percentages are relative to US recommendations for adults.
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.
The principal soluble carbohydrates of mature soybeans are the disaccharide sucrose (range 2.5–8.2%), the trisaccharide raffinose (0.1–1.0%) composed of one sucrose molecule connected to one molecule of galactose, and the tetrasaccharide stachyose (1.4 to 4.1%) composed of one sucrose connected to two molecules of galactose. While the oligosaccharides raffinose and stachyose protect the viability of the soybean seed from desiccation (see above section on physical characteristics) they are not digestible sugars, and therefore contribute to flatulence and abdominal discomfort in humans and other monogastric animals; compare to the disaccharide trehalose. Undigested oligosaccharides are broken down in the intestine by native microbes, producing gases such as carbon dioxide, hydrogen, and methane.
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 soybeans 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.
Further information: Soy protein
For human consumption, soybeans must be cooked with "wet" heat to destroy the trypsin inhibitors (serine protease inhibitors). Raw soybeans, including the immature green form, are toxic to humans, swine, chickens, and in fact, all monogastric animals.
Soybeans are considered by many agencies to be a source of complete protein. A complete protein is one that contains significant amounts of all the essential amino acids that must be provided to the human body because of the body's inability to synthesize them. For this reason, soy is a good source of protein, amongst many others, for vegetarians and vegans or for people who want to reduce the amount of meat they eat. According to the US Food and Drug Administration:
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.
The gold standard for measuring protein quality, since 1990, is the Protein Digestibility Corrected Amino Acid Score (PDCAAS) and by this criterion soy protein is the nutritional equivalent of meat, eggs, and casein for human growth and health. Soybean protein isolate has a biological value of 74, whole soybeans 96, soybean milk 91, and eggs 97.
Soy protein is essentially identical to that of other legume seeds. Moreover, soybeans can produce at least twice as much protein per acre than any other major vegetable or grain crop besides hemp, five 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.
Consumption of soy may also reduce the risk of colon cancer, possibly due to the presence of sphingolipids.
Soybean output in 2005Top Soybean Producers
(million metric tons)
United States 80.5
European Union 0.6
World Total 230.9
Soybeans are an important global crop, providing oil and protein. In the United States, the bulk of the crop is solvent-extracted with hexane, and the "toasted" defatted soymeal (50% protein) then makes possible the raising of farm animals (e.g. chicken, hog, turkey) on an industrial scale never before seen in human history. A very small proportion of the crop is consumed directly by humans. Soybean products do, however, appear in a large variety of processed foods.
During World War II, soybeans became important in both North America and Europe chiefly as substitutes for other protein foods and as a source of edible oil. During World War II, the soybean was discovered as fertilizer by the United States Department of Agriculture. In the 1960-1 Dillion round of the General Agreement on Tariffs and Trade (GATT), the United States secured tariff-free access for its soybeans to the European market. In the 1960s, the United States exported over 90% of the world's soybeans. In 2005, top soybeans exporters are Brazil (39% of world soybean exports), United States (37%) and Argentina (16%), while top importers are China (41% of world soybean imports), European Union (22%), Japan (6%) and Mexico (6%).
Cultivation is successful in climates with hot summers, with optimum growing conditions in mean temperatures of 20 to 30 °C (68 to 86 °F); temperatures of below 20 °C and over 40 °C (68 °F, 104 °F) retard growth significantly. They can grow in a wide range of soils, with optimum growth in moist alluvial soils with a good organic content. Soybeans, like most legumes, perform nitrogen fixation by establishing a symbiotic relationship with the bacterium Bradyrhizobium japonicum (syn. Rhizobium japonicum; Jordan 1982). For best results, though, an inoculum of the correct strain of bacteria should be mixed with the soybean (or any legume) seed before planting. Modern crop cultivars generally reach a height of around 1 m (3.3 ft), and take 80–120 days from sowing to harvesting.
The U.S., Brazil, Argentina, China and India are the world's largest soybean producers and represent more than 90% of global soybean production. The U.S. produced 75 million tons of soybeans in 2000, of which more than one-third was exported. In the 2010-2011 production year, this figure is expected to be over 90 million tonnes.Other leading producers are Brazil, Argentina, Paraguay, China, and India.
American soil scientist Dr. Andrew McClung, who first showed that the ecologically biodiverse savannah of the Cerrado region of Brazil could grow profitable soybeans, was awarded the 2006 World Food Prize on October 19, 2006. Unfortunately, it is turning into a Pandora's box.
Soybean plants are vulnerable to a wide range of bacterial diseases, fungal diseases, viral diseases and parasites.
Further information: List of soybean diseases
Different varieties of soybeans being grown together
Soybeans are one of the "biotech food" crops that have been genetically modified, and genetically modified soybeans are being used in an increasing number of products. In 1995, Monsanto Company introduced Roundup Ready (RR) soybeans that have been genetically modified to be resistant to Monsanto's herbicide Roundup through substitution of the Agrobacterium sp. (strain CP4) gene EPSP (5-enolpyruvyl shikimic acid-3-phosphate) synthase. The substituted version is not sensitive to glyphosate.
In 1997, about 8% of all soybeans cultivated for the commercial market in the United States were genetically modified. In 2010, the figure was 93%. As with other "Roundup Ready" crops, concern is expressed over damage to biodiversity. A 2003 study concluded the RR gene had been bred into so many different soybean cultivars, there had been little decline in genetic diversity, but "diversity was limited among elite lines from some companies".
The widespread use of such types of GM soybeans in the Americas has caused problems with exports to some regions. GM crops require extensive certification before they can be legally imported into the European Union, where there is considerable supplier and consumer reluctance to use GM products for consumer or animal use. Difficulties with coexistence and subsequent traces of cross-contamination of non-GM stocks have caused shipments to be rejected and have put a premium on non-GM soy.
A 2006 United States Department of Agriculture report found the adoption of genetically engineered (GE) soy, corn and cotton reduced the amount of pesticides used overall, but did result in a slightly greater amount of herbicides used for soy specifically. The use of GE soy was also associated with greater conservation tillage, indirectly leading to better soil conservation, as well as increased income from off-farming sources due to the greater ease with which the crops can be managed. Most farmers adopted the GE crops to improve yields, save time and reduce the amount of money spent on pesticides. The use of GE soy also permits the use of a herbicide that is less toxic to humans. Though the overall estimated benefits of the adoption of GE soybeans in the United States was $310 million, the majority of this benefit was experienced by the companies selling the seeds (40%), followed by biotechnology firms (28%) and farmers (20%).
In 2010, a team of American scientists announced they had decoded the genome of the soybean - the first legume to be sequenced.