Bean

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Bean is a common name for edible plant seeds or seed pods of several members of the Legume family (Fabaceae, formerly Leguminosae) or the various leguminous trees and shrubs that produce these seeds or pods.

The various species of bean plants include some of the very first plants cultivated by people in both the Old and the New Worlds. They have been and continue to be an important part of the human food supply, providing protein, vitamins, and other nutrients. In recent years, bean consumption has increased due mainly to economic progress in India, home to many vegetarians, and to their increased use in developed countries as people move to healthier diets (FAO 2005).

Beans, especially soybeans, which are now the largest bean crop grown, provide other products as well as food. They are also important for their role in fixing nitrogen, which replenishes the soil in which they are grown. They do this through a cooperative, mutually beneficial, symbiotic relationship with nitrogen-fixing bacteria.

Common beans on the plant

Contents

Name

"Bean" originally meant the seed of the broad bean, but was later broadened to include members of the genus Phaseolus such as the common bean and the runner bean, and the related genus Vigna. The term is now applied in a general way to many other related plants, such as soybeans, peas, lentils, vetches, and lupines.

"Bean" can be used as a near synonym of "pulse," an edible legume, though the term "pulses" is usually reserved for leguminous crops harvested for their dry grain. The term pulses usually excludes crops mainly used for oil extraction (like soybean and peanut), or those used exclusively for forage (like clover and alfalfa). Beans are often harvested when immature and are eaten as a vegetable, known as "green beans"; in this case they also are not called "pulses."

In English usage, beans sometimes also refer to seeds or other organs of non-legumes, for example coffee beans, castor beans, and cocoa beans (which resemble bean seeds), and vanilla beans (which resemble the pods).

Old World beans

In the Old World, beans were first cultivated in the Middle East, perhaps around 10,000 years ago. Along with their fellow legumes the pea (Pisum sativum), the chickpea (Cicer arietinum), and the bitter vetch (Vicia ervilia), these cultivated plants included the broad bean (Vicia faba) and the lentil (Lens culinaris) (although it is not always called a bean). The soybean (Glycine max) was also cultivated very early in China. Some of the other Old World beans are the adzuki (or azuki) bean (Phaseolus angularis), the hyacinth bean (Dolichos lablab), the winged bean (Psophocarpus tetragonolobus), the guar bean (Cyamopsis tetragonoloba), and the pigeon pea (Cajanus cajan) (Walker 2005).

Broad beans

Vicia faba, known as the broad bean, fava bean, faba bean, horse bean, field bean or tic bean, is native to north Africa and southwest Asia, and is extensively cultivated elsewhere. Although usually classified in the same genus Vicia as the vetches, some botanists treat it in a separate monotypic genus as Faba sativa Moench.

Broad bean plant
broad beans in the pod

The broad bean plant is upright, 0.5-1.7 meters (2-5 feet) tall, with stout stems with a square cross-section. The leaves are 10-25 cm (4-10 inches) long with 2-7 leaflets, and of a gray-green color. Unlike most other vetches, the leaves do not have tendrils for climbing over other vegetation. The flowers are 1-2.5 cm (0.4-1 inches) long, with five petals, the standard petal white, the wing petals white with a black spot, and the keel petals white.

The fruit is a broad leathery pod, green maturing blackish-brown, with a densely downy surface. In the wild species, the pods are 5-10 cm (2-4 inches) long and 1 cm (0.4 inches) diameter, but many modern cultivars developed for food use have pods 15-25 cm long (6-10 inches) and 2-3 cm (about an inch) thick. Each pod contains 3-8 seeds; round to oval and 5-10 mm (0.2-0.4 inches) in diameter in the wild plant, usually flattened and up to 20-25 mm (0.8-1.2 inches) long, 15 mm (0.6 inches) broad, and 5-10 mm (0.2-0.4 inches) thick in food cultivars.

Broad beans require a cool season to develop best and in some places are sown in fall as a winter crop and harvested in spring.

Broad beans were an important crop throughout ancient and Medieval times. In ancient Rome, they began to be cultivated in order to feed livestock as well as for humans. In recent times, they have become less important as a human food and are mainly grown for animal feed. China is the largest grower today, producing about 60 percent of the world's supply. Europe and North Africa are also centers of broad bean cultivation (Muehlbauer 1997).

Lentils

Illustration of the lentil plant, 1885

The lentil (Lens culinaris) is a brushy annual plant, about 40 cm (16 inches) tall. Its seeds are lens-shaped (from which comes the word "lens"). They grow in pods, usually with two seeds in each. With 25 percent protein, it is the vegetable with the highest level of protein other than soybeans, and because of this it is a very important part of the diet in many parts of the world, and especially South Asia, which has a large vegetarian population.

A variety of lentils exist with colors that range from yellow to red-orange to green, brown and black. The colors of the seeds when removed from the pods also vary, and there are large and small varieties. They are sold in many forms, with or without the pods, whole or split.

In South Asia, lentils are known as dal, as are most sorts of dried legumes. The dishes made predominantly of lentils are also known as dal.

Lentils are relatively tolerant to drought and are grown throughout the world. About half of the worldwide production of lentils is from India, most of which is consumed in the domestic market.

A famous variety of small green lentils known for their earthy flavor is grown in Le Puy, France. These Le Puy lentils (lentilles du Puy) were the first dry vegetable protected by the French Appelation d'Origine Controlée designation.

Soybeans

The Soybean (U.S.) or Soya bean (UK) (Glycine max) is native to eastern Asia. It is an annual plant, which may vary in growth habit and height. It may grow prostrate, not growing above 20 cm (7.8 inches) or be stiffly erect, growing to 2 meters (6.5 feet). The pods, stems, and leaves are covered with fine brown or gray pubescence. The leaves are trifoliate (sometimes with 5 leaflets), the leaflets 6-15 cm (2-6 inches) long and 2-7 cm (1-3 inches) broad; they fall before the seeds are mature. The small, inconspicuous, self-fertile flowers are borne in the axil of the leaf and are either white or purple; the fruit is a hairy pod that grow in clusters of 3-5, with each pod 3-8 cm (1-3 inches) long and usually containing 2-4 (rarely more) seeds 5-11 mm (0.2-0.5 inches) in diameter.

Like corn and 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.

Varieties of soybeans are used for many purposes.

Soybeans have been a crucial crop in eastern Asia since long before written records, and they are still a major crop in China, Korea, and Japan today. Soybeans were first introduced to Europe in the early 1700s and the United States in 1765, where it was first grown for hay. Benjamin Franklin wrote a letter in 1770 mentioning sending soybeans home from England. Soybeans did not become an important crop outside of Asia until about 1910.

Cultivation is successful in climates with hot summers, with optimum growing conditions in mean temperatures of 20°C to 30°C (68°F to 86°F); temperatures of below 20°C and over 40°C (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.

Although soybeans are native to southeast Asia, 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.

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" cultivars are generally not suitable for mechanical combine harvesting because they have a tendency for the pods to shatter on reaching maturity.

Among the legumes, the soybean, also classed as an oilseed, is pre-eminent for its high (38-45 percent) protein content as well as its high (20 percent) oil content. Soybeans are the leading agricultural export of the United States. 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 smaller percentage of soybeans are used directly for human consumption.

Soybeans may be boiled whole in their green pod and served with salt, under the Japanese name edamame. Soybeans prepared this way are a popular local snack in Hawai'i, where, as in China, Japan, and Korea the bean and products made from the bean (miso, natto, tofu, douchi, doenjang, ganjang and others) are a popular part of the diet.

The beans can be processed in a variety of ways. Common forms of soy (or soya) include soy meal, 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 soybean oil. Soybeans are also the primary ingredient involved in the production of soy sauce (or shoyu in Japanese from which the English word "soy" is said to come).

Soybeans grow throughout Asia and North and South America.

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). It is the starting material for production of soy concentrate and soy protein isolate.

Infant formulas based on soy are used by lactose-intolerant babies, and for babies that are allergic to human milk proteins and cow milk proteins. The formulas are sold in powdered, ready to feed, or concentrated liquid forms.

It has been recommended internationally by pediatric associations that soy formulas not be used as the primary or sole source of nutrition for infants due to the high risk of several deficiencies, including calcium and zinc.

Many traditional dairy products have been imitated using processed soybeans, and imitation products such as "soy milk," "soy yogurt," and "soy cream cheese" are readily available in most supermarkets. These imitation products are derived from extensive processing to produce a texture and appearance similar to the real dairy-based ones. 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.

Soybeans are also used in industrial products, including oils, soap, cosmetics, resins, plastics, inks, crayons, solvents, and biodiesel. Soybeans are also used as fermenting stock to make a brand of vodka.

Henry Ford promoted the soybean, helping to develop uses for it both in food and in industrial products, even demonstrating auto body panels made of soy-based plastics. Ford's interest lead to 2 bushels of soybeans being used in each Ford car as well as products like the first commercial soy milk, ice cream, and all-vegetable non-dairy whipped topping. The Ford development of so called soy-based plastics was based on the addition of soybean flour and wood flour to phenolformaldehyde plastics.

Today, very high quality textile fibers are made commercially from soy pulp, a byproduct of tofu production.

New World beans

Beans were cultivated early in the New World, both in South and North America. The most important bean species from the New World is the common bean (Phaseolus vulgaris). Other New World beans include Lima beans (Phaseolus limensis), runner beans (Phaseolus coccineus), tepary beans (Phaseolus acutifolius, var. latifolius), and butter beans (Phaseolus lunatus).

Common beans

Kidney beans

The common bean (Phaseolus vulgaris) was domesticated independently in ancient Mesoamerica and the Andes, and is now grown worldwide for its edible bean, popular both dry and as a green bean. The leaf is occasionally used as a leaf vegetable, and the straw is used for fodder. Along with squash and maize, beans were the "three sisters" that provided the foundation of Native American agriculture.

The common bean is a highly variable species. Bush varieties form erect bushes 20-60 cm (8-24 inches) tall, while pole or running varieties form vines 2-3 meters (6-10 feet) long. All varieties bear alternate, green or purple leaves, divided into three oval, smooth-edged leaflets, each 6-15 cm (2.5-6 inches) long and 3-11 cm (1-4 inches) wide. The white, pink, or purple flowers are about 1 cm (0.4 inches) long, and give way to pods 8-20 cm (3-8 inches) long, 1-1.5 cm (about 0.5 inches) wide, green, yellow, black or purple in color, each containing 4-6 beans. The beans are smooth, plump, kidney-shaped, up to 1.5 cm (0.6 inches) long, range widely in color, and are often mottled in two or more colors. There are many cultivated varieties of common beans including navy beans, kidney beans, pinto beans, black beans, and many others.

Green beans

Before they are eaten, the raw bean seeds should be boiled for at least ten minutes to degrade a toxic compound—the lectin phytohaemagglutinin—found in the bean, which would otherwise cause severe gastric upset. This compound is present in many varieties (and in some other species of bean), but is especially concentrated in red kidney beans. Although in the case of dry beans, the ten minutes required to degrade the toxin is much shorter than the hours required to fully cook the beans themselves, outbreaks of poisoning have been associated with the use of slow cookers whose low cooking temperatures may be unable to degrade the toxin. Sprouts of beans high in haemaglutins should not be eaten. Red kidney beans, especially, should not be sprouted.

The common bean is high in starch, protein, and dietary fiber, and an excellent source of iron, potassium, selenium, molybdenum, thiamine, vitamin B6, and folic acid.

Lima beans

Lima beans

The Lima bean (Phaseolus lunatus) is grown as a vegetable for its mature and immature beans. It is also known as Haba bean, Burma bean, Guffin bean, Hibbert bean, Java bean, Sieva bean, Rangood bean, Madagascar bean, Paiga, Paigya, Prolific bean, Civet bean and Sugar bean

The lima bean is of Andean and Mesoamerican origin. Two separate domestication events are believed to have occurred. The first, taking place in the Andes around 6500 B.C.E., produced a large-seeded variety (Lima type), while the second, taking place most likely in Mesoamerica around 800 C.E., produced a small-seeded variety (Sieva type). By around 1300 C.E., cultivation spread to North America.

The small-seeded wild form (Sieva type) is found distributed from Mexico to Argentina, generally below 1600 meters above sea level, while the large-seeded wild form (Lima type) is found distributed in Ecuador and the north of Peru, between 320 and 2030 meters above sea level.

Both bush and vine varieties exist, the latter from one to four meters in height. The bush varieties mature earlier than the pole varieties. The pods are up to 15 cm long. The mature seeds are 1 to 3 cm long and oval to kidney shaped. In most varieties the seeds are quite flat, but in the "potato" varieties the shape approaches spherical. White seeds are common, but black, red, orange and variously mottled seeds are also known. The immature seeds are uniformly green.

Runner beans

Runner beans

The runner bean (Phaseolus coccineus) is often called the scarlet runner bean since most varieties have red flowers and multicolored seeds, though some have white flowers and white seeds. It is native to the mountains of Central America.

The runner bean differs from the common bean in several respects: the cotyledons stay in the ground during germination, and the plant is a perennial with tuberous roots (though it is usually treated as an annual).

The green pods are edible whole, but in some varieties (the scarlet runner) tend to become fibrous early, and only the seeds within are eaten. The seeds can be used fresh or as dried beans. The starchy roots are still eaten by Central American Indians. The scarlet runner is widely grown for its attractive flowers by people who would never think of eating it.

Phaseolus coccineus subsp. darwinianus is a cultivated subspecies of P. coccineus, it is commonly referred to as the Botil bean in Mexico.

References

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