Soybeans
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Wikipedia-Article "Soybeans"
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Soybean(s) (U.S.) or soya bean (UK): A legume, the botanical name of which is Glycine max (L.) Merrill. It is a summer annual varying in height from less than a foot to more than 6 feet with a growth habit from stiffly erect to prostrate; cultivated varieties(cultivar) may reach a height of 3 feet or more; the seeds (soybeans) are borne in hairy-pods that grow in clusters of three to five with each pod usually containing 2 or 3 or more seeds.
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Overview
The word soy is derived from the Japanese word shoyu (soy sauce/soya sauce).
Origin
Soybeans originated in Eastern Asia and were used there as food long before written records; and first introduced to the United States early in the 19th century where it was first grown for hay. The progenitor of the modern soybean was a vine-like plant,that grew prone on the ground.
Nutrition and Use
Among the legumes, the soybean--also classed as an oilseed--is pre-eminent for its high(38-45%) protein content as well as its high(20%) oil content. Soybeans are the most important cash crop in the United States and the leading agricultural export. The bulk of the soybean crop is grown for oil production, with the high- protein defatted and "toasted" soy meal used as livestock feed. A very, very small amount of soybeans are used directly for human consumption.
Physical characteristics
Soybeans occur in various sizes, and in several hull or seed coat colors, including black, brown, blue, yellow, and mottled. The hull of the mature bean is hard, water resistant, and protects the cotyledon and hypocotyl (or "germ") from damage. 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. It is a remarkable fact that seed soy protein can undergo dessication yet revive after water absorption.
Applications
Soybeans can be broadly classified as "vegetable" (garden) or field(oil) types. Vegetable types cook more easily, have a mild nutty flavor, better texture, are larger in size, higher in protein, and lower in oil than field types. Tofu and soymilk producers prefer the higher protein cultivars bred from vegetable soybeans originally brought to the United States in the late 1930s. The "garden" varieties are generally not suitable for mechanical combine harvesting because they have a tendency to shatter from the pod on reaching maturity.
Soybeans may be boiled whole (in the green pod) and served with salt, often under the Japanese name edamame. Soybeans prepared this way are a popular local snack in Hawai'i, where, like in Japan, China, and Korea, the bean and products made from the bean (miso, natto, tofu, douchi,doenjang, Ganjang etc.) are a significant part of the diet.
Soybean processing
The beans can be processed in a variety of ways. Common forms of soy (or soya) include soy meal ( used as animal feed), soy flour, soy milk, tofu, textured vegetable protein (TVP, which is made into a wide variety of vegetarian foods, some of them intended to imitate meat), tempeh, soy lecithin and vegetable oil. Soybeans are also the primary ingredient involved in the production of soy sauce (or shoyu).
Soybean oil
In processing soybeans for oil extraction and subsequent soy flour production, selection of high quality, sound, clean, dehulled--yellow soybeans-- is very important. Soybeans having a dark colored seed coat, or even beans with a dark hilum will inadvertently leave dark specks in the flour, an undesirable factor when used in food products. All commercial soybeans in the United States are yellow or yellow brown.
Soybean oil makes up 80% of the edible oil consumption in the United States. Soybean oil extraction is performed on a large scale in the U.S. The soybeans are cracked, adjusted for moisture content, rolled into flakes and solvent extracted with commercial hexane. The oils are blended for their applications, and sometimes hydrogenated. The oils are exported abroad, sold as vegetable oil, or end up in a wide variety of processed foods. New processes increasingly prepare protein isolates for use as food additives or health supplements. The remaining soybean husks are used mainly as animal feed.
Soybean meal
Soybean meal,the material remaining after solvent extraction of soybean flakes, with a 50% protein content and toasted (a misnomer because the heat treatment is with moist steam), provided the energy for the American revolution, beginning in the 1930s, of growing farm animals such as poultry and swine on an industrial scale; and more recently the aquaculture of catfish. Soy flour refers to defatted soybeans where special care was taken during desolventizing(not toasted) in order to minimize denaturation of the protein-to retain a high Nitrogen Solubility Index(NSI)--for uses such as extruder texturizing (TVP).
Other products
Soybeans are also used in industrial products including oils, soap, cosmetics, resins, plastics, inks, crayons, solvents, and biodiesel.
Soybean production
Soybeans are native to southeast Asia, but 45 percent of the world's soybean area, and 55 percent of production, is in the United States. The U.S. produced 75 million metric tons of soybeans in 2000, of which more than one-third was exported. Other leading producers are Brazil, Argentina, China, and India. Much of the U.S. production is either fed to animals or exported, though U.S. consumption of soybeans and other soy foods by people has been increasing. Environmental groups, such as Greenpeace have reported that soybean cultivation and the threat to increase soybean cultivation in Brazil is destroying huge areas of Amazon rainforest--trees many hundreds of years old-- and encouraging deforestation.
Genetic Modification
Soybeans are one of the crops that are being genetically modified, and GMO soybeans are being used in an increasing number of products. Currently, 80% of all soybeans cultivated for the commercial market are genetically modified. Monsanto is the world's leader in genetically modified soy for the commercial market. About ten years ago Monsanto introduced "Roundup Ready"(RR) soybeans that have had a complete copy of a gene(plasmid) from the bacteria, Agrobacterium sp. strain CP4, inserted, by means of a gene gun, into its genome that allows the transgenic plant to survive being sprayed by this non-selective, glyphosate-based herbicide. Roundup kills conventional soybeans. RR soybeans allow a farmer to reduce tillage or even to sow the seed directly into an unplowed field--No Plow tillage.
Imitations
Many traditional dairy products have been imitated using soybeans, and products such as soy milk, soy yogurt and soy cream cheese are readily available in most supermarkets. These products have similar texture and appearance to milk-based ones; however regular soy milk does not contain significant amounts of calcium, since the high calcium content of soybeans is bound to the insoluble constituents and remains in the pulp. Many manufacturers of soy milk now sell calcium-enriched products as well. Tofu often contains high amounts of this important mineral since calcium salts are used to coagulate the protein in soy milk when creating tofu. Additionally, soy protein has been found to reduce renal excretion of calcium, an effect that is reinforced by soy products' high potassium content.
Nutrition and health effects
Protein
Soybeans are considered a source of complete protein, i.e., protein 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 important to many vegetarians and vegans. Soy protein is essentially identical to that of other legume seeds. The only non-legume to have an almost identical protein profile to soy is the cereal oat (Avena sativa), and perhaps quinoa. Soybeans also have the highest protein yield per acre of all crops.
Infants
Infants fed normal adult soy milk for any length of time, have become extremely malnourished and even died. This is so because undiluted soy milk contains about the same proportion of protein as cow's milk~ around 3.5% which is way too much for a human infant--human milk is about 1% protein. Infant formula prepared from soy isolates, and earlier from soy flour, effectively alleviates--hypoallergenic substitute-- allergenic symptoms due to an allergic reaction to human or cow's milk. Soy allergies are also known to occur in human adults.
Vitamins and Minerals
Of any studied legume, whole soybeans have the highest levels of phytic acid, an organic acid and mineral chelator present in many plant tissues, especially bran and seeds, which binds to certain ingested minerals—calcium, magnesium, iron, and especially zinc—in the intestinal tract, and reduces the amount the body assimilates. For people with a particularly low intake of essential minerals, especially young children and those in developing countries, this effect can be undesirable. However, dietary mineral chelators help prevent over-mineralization of joints, blood vessels, and other parts of the body, which is most common in older persons. The Journal of Environmental Nutrition (April 2004 volume 27 issue 4) has also stated phytic acid may be considered a phytonutrient, providing an antioxidant effect. Scientific research [1] also indicates that it may reduce the risk of colon cancer.
Other nutritive value
In spite of the chelating effects of phytic acid, the tough soybean husks used mainly for animal feed remain a good source of magnesium, potassium, phosphorus, calcium, and manganese. They are also high in fiber and vitamin C.
Soybeans also contain isoflavones, forms of phytoestrogen that are considered by some nutritionists and physicians to be useful in the prevention of cancer, though very controversial and also blamed for some thyroid health problems. Isoflavones are polyphenol compounds, produced primarily by beans and other legumes, including peanuts and chickpeas.
Research
The first research on soybeans in the United States was conducted by George Washington Carver at Tuskeegee, Alabama but he decided it was too exotic a crop for the poor black farmers of the South so he turned his attention to peanuts. He also encouraged farmers to use crop rotation. Peanuts, soybeans, sweet potatoes or other plants that would replenish the soil with nitrogen and minerals were planted for two years and then cotton on the third year.
A 1985 animal study showed that young rats fed large amounts of soy products as their primary food source showed an increased risk of pancreatic cancer. This is probably because rats are extremely sensitive to dietary protease inhibitors like those found in soybeans, which can disrupt the action of digestive enzymes needed to break down protein. This condition has not been found in many other animals, and is not known to occur in humans.
See also
- Biodiesel
- Protein per unit area
- Soybean rust
- Soy milk
- Soy protein
- Soy pulp
- Soy sauce
- Soybean cyst nematode
- Vegetable oil
References
- The History of Soybeans. North Carolina Soybean Producers Association. URL accessed on July 25, 2005.
- American Soybean Association. URL accessed on July 25, 2005.
- [2]