Phaseolus vulgaris

Phaseolus vulgaris
	A variety of the common bean with flat pods
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Fabales
Family:	Fabaceae
Genus:	Phaseolus
Species:	P. vulgaris
Binomial name
	Phaseolus vulgaris; L.

Phaseolus vulgaris, the common bean, is a herbaceous annual plant, grown worldwide for its edible beans, used both dry and green. The leaf is occasionally used as a leaf vegetable, and the straw is used for fodder.

The common bean is a highly variable species with a long history of cultivation. Botanically, the common bean is classified as a dicotyledon. Beans are legumes, so they acquire their nitrogen through an association with rhizobia: species of nitrogen-fixing bacteria. There are a large number of commercial varieties, classified into bush and pole (running) varieties. Pods contain 4–6 beans, which are smooth, plump, kidney-shaped, and up to 1.5 cm long, ranging widely in color.

The commercial production of beans is well-distributed worldwide, with countries in Asia, Africa, Europe, Oceania, South and North America all among the top bean growers. Brazil and India are the largest producers of dry beans while China produces, by far, the largest quantity of green beans, almost as much as the rest of the top ten growers combined. 23 million tonnes of dry common beans and 17.1 million tonnes of green beans were grown worldwide in 2010. The other major type of bean is the broad bean (Vicia faba).

Beans, squash and maize constitute the "Three Sisters" that provide the foundation of Native American agriculture.

Description [edit]

Blossoms of Common bean

The common bean is a highly variable species with a long history. Bush varieties form erect bushes 20–60 centimeters (7.9–24 in) tall, while pole or running varieties form vines 2–3 meters (6 ft 7 in–9 ft 10 in) long. All varieties bear alternate, green or purple leaves, which are divided into three oval, smooth-edged leaflets, each 6–15 centimeters (2.4–5.9 in) long and 3–11 centimeters (1.2–4.3 in) wide. The white, pink, or purple flowers are about 1 cm long, and they give way to pods 8–20 centimeters (3.1–7.9 in) long and 1–1.5 cm wide. These may be green, yellow, black, or purple in color, each containing 4–6 beans. The beans are smooth, plump, kidney-shaped, up to 1.5 cm long, range widely in color, and are often mottled in two or more colors.

Dry beans [edit]

Similar to other beans, the common bean is high in starch, protein and dietary fiber and is an excellent source of iron, potassium, selenium, molybdenum, thiamine, vitamin B6, and folate.

Dry beans will keep indefinitely if stored in a cool, dry place, but as time passes, their nutritive value and flavor degrade and cooking times lengthen. Dried beans are almost always cooked by boiling, often after being soaked for several hours. While the soaking is not strictly necessary, it shortens cooking time and results in more evenly textured beans. In addition, soaking beans removes 5 to 10 percent of the gas-producing sugars that can cause flatulence for some people.^[1] The several methods include overnight soaking, and the power soak method, in which beans are boiled for three minutes and then set aside for 2–4 hours. Before cooking, the excess water is drained and discarded. Common beans take longer to cook than most pulses: cooking times vary from one to four hours, but are substantially reduced with pressure cooking.

In Mexico, Central America and South America, the traditional spice to use with beans is epazote, which is also said to aid digestion. In East Asia, a type of seaweed, kombu, is added to beans as they cook for the same purpose. Salt, sugar, and acidic foods such as tomatoes may harden uncooked beans, resulting in seasoned beans at the expense of slightly longer cooking times.

Dry beans may also be bought cooked and canned as refried beans, or whole with water, salt, and sometimes sugar.

Green beans

Green beans [edit]

Main article: Green beans

The three commonly known types of green beans are: string or runner beans, stringless or French beans (depending on whether the pod has a tough, fibrous "string" running along its length), and 'snap beans, which may be round or have a thin, flat pod that requires less cooking time. Compared to dry beans, they provide less starch and protein and more vitamin A and vitamin C. The green beans are often steamed, boiled, stir-fried, or baked in casseroles.

Shelling beans [edit]

Diversity in dry common beans

Shell, shelled, or shelling beans are beans removed from their pods before being cooked or dried. Common beans can be used as shell beans, but the term also refers to other species of beans whose pods are not typically eaten, such as lima beans, soybeans, peas, and fava beans. Fresh shell beans are nutritionally similar to dry beans, but are prepared more like a vegetable, often being steamed, fried, or made into soups.

Popping beans [edit]

The nuña is an Andean subspecies, Phaseolus vulgaris subsp. nunas (formerly Phaseolus vulgaris (Nuñas group)), with round, multicolored seeds that resemble pigeon eggs. When cooked on high heat, the bean explodes, exposing the inner part, in the manner of popcorn and other puffed grains.

Toxicity [edit]

The toxic compound phytohaemagglutinin, a lectin, is present in many common bean varieties, but is especially concentrated in red kidney beans. White kidney beans contain about a third as much toxin as the red variety; broad beans (Vicia faba) contain 5 to 10% as much as red kidney beans.^[2]

Phytohaemagglutinin can be deactivated by boiling beans for ten minutes; the ten minutes at boiling point (100 °C (212 °F)) are sufficient to degrade the toxin, but not to cook the beans. For dry beans, the U.S. Food and Drug Administration (FDA) also recommends an initial soak of at least 5 hours in water which should then be discarded.^[2]

If the beans are cooked at a temperature below boiling (without a preliminary boil), as in a slow cooker, the toxic effect of haemagglutinin is increased: beans cooked at 80 °C (176 °F) are reported to be up to five times as toxic as raw beans.^[2] Outbreaks of poisoning have been associated with cooking kidney beans in slow cookers.^[2]

The primary symptoms of phytohaemagglutinin poisoning are nausea, vomiting, and diarrhea. Onset is from one to three hours after consumption of improperly prepared beans, and symptoms typically resolve within a few hours.^[2] Consumption of as few as four or five raw, soaked kidney beans can cause symptoms.^[2]

Beans are high in purines, which are metabolized to uric acid. Uric acid is not a toxin as such, but may promote the development or exacerbation of gout. For this reason, people with gout are often advised to limit their consumption of beans.^[3]

Varieties [edit]

Black turtle beans

Many well-known bean varieties belong to this species, and none of the lists below are in any way exhaustive. Both bush and running (pole) varieties exist. The colors and shapes of pods and seeds vary over a wide range.

Black turtle beans [edit]

The Black turtle bean is a small, shiny variety of common beans (Phaseolus vulgaris), especially popular in Latin American cuisine.

Cranberry and borlotti beans [edit]

Cranberry beans originated in Colombia as the cargamanto. Borlotti or Roman beans are a variety of cranberry bean bred in Italy to have a thicker skin. They are much used in Mediterranean cuisine.

Flageolet beans [edit]

Flageolet beans are often eaten in France. They are small, light green, and kidney shaped. The texture is firm yet creamy if shelled and cooked when fresh but semi-dry.

"Painted Pony" dry beans (Phaseolus vulgaris)

Kidney beans [edit]

Kidney beans, also known as red beans, are named for their visual resemblance in shape and color to kidneys. Kidney beans are commonly used in chili soup chili con carne and are an integral part of the cuisine in northern regions of India. They are also used in New Orleans and much of southern Louisiana for the classic Monday Creole dish of red beans and rice.

Pea beans [edit]

Pea beans have been recorded in Britain since the 16th century.^[4] The seeds are unusual as they are distinctly bicoloured, being red-brown and white. The plants are a typical climbing bean. The beans are either eaten in the pod like French beans or they may be harvested when mature and eaten as other dried beans.^[5]

Pink beans [edit]

Pink beans are small, pale pink, oval-shaped beans, and are also known by the Spanish name habichuelas rosadas.^[6] The Santa Maria pinquito (Spanglish = pink and small), is commercially grown on the mesas above Santa Maria, California, and is a necessary ingredient in Santa Maria Style BBQ.

Assortment of beans at a market in Kathmandu, Nepal

Pinto beans [edit]

Pinto beans are named for their mottled skin, and are common across America. They are the most common bean in the United States^[7] and northwestern Mexico,^[8] and are most often eaten whole in broth or mashed and refried. Either whole or mashed, they are a common filling for burritos. The young pods may also be harvested and cooked as green pinto beans.

White beans [edit]

Navy beans or haricot beans are particularly popular in the United Kingdom and the United States. Other white beans include cannellini, a popular variety in central and southern Italy, which is related to the kidney bean. White beans are the most abundant plant-based source of phosphatidylserine (PS) known.^[9]

Yellow beans [edit]

Sinaloa Azufrado, Sulphur, Mayocoba, and Peruano (also called canary) are types of yellow beans.

Peruano beans (also called canary or mayacoba beans) are small, oval, yellow beans about 1/2 inch (1 cm) long with a thin skin. Peruano beans have a creamy texture when cooked, and are one of the top-selling beans in Mexico City since 2005 (despite the name, they are native to Mexico). However, yellow beans are uncommon in the United States due to a controversial patent issued in 1999 to John Proctor, who selected and named a strain of yellow bean from seeds he brought back from Mexico. U.S. Patent No. 5,894,079 (the Enola or yellow bean patent) granted POD-NERS, LLC., exclusive right to import and sell yellow beans in the United States from 1999 through 2008, when the patent was rejected after reexamination.^[10]^[11]

Production [edit]

Climbing beans growing in DR Congo

Bush bean field in Laos

In 2010, total world production of dry beans was 23 million metric tons. The area harvested to dry beans was over 30 million hectares.^[12] World production of green beans in 2010 was 17.7 million ton, harvested at 15.1 million hectares.^[12]