A bean is the seed of any plant in the legume family (Fabaceae) used as a vegetable for human consumption or animal feed.[1] The seeds are often preserved through drying, but fresh beans are also sold. Most beans are traditionally soaked and boiled, but they can be cooked in many different ways,[2] including frying and baking, and are used in many traditional dishes throughout the world. The unripe seedpods of some varieties are also eaten whole as green beans or edamame (immature soybean), but fully ripened beans contain toxins like phytohemagglutinin and require cooking.
The word 'bean', for the Old World vegetable, existed in Old English,[3] long before the New World genus Phaseolus was known in Europe. With the Columbian exchange of domestic plants between Europe and the Americas, use of the word was extended to pod-borne seeds of Phaseolus, such as the common bean and the runner bean, and the related genus Vigna. The term has long been applied generally to seeds of similar form,[4] such as Old World soybeans and lupins, and to the fruits or seeds of unrelated plants such as coffee beans, vanilla beans, castor beans, and cocoa beans.[5]
See also: Columbian exchange.
Beans were among the first plants to be domesticated. Broad or fava beans are in their wild state the size of a small fingernail; they were first gathered in Afghanistan and the Himalayan foothills. An early cultivated form was grown in Thailand from the early seventh millennium BCE, predating ceramics.[6] Beans were deposited with the dead in ancient Egypt. Not until the second millennium BCE did cultivated, large-seeded broad beans appear in the Aegean region, Iberia, and transalpine Europe.[7] In the Iliad (8th century BCE), there is a passing mention of beans and chickpeas cast on the threshing floor.[8]
The oldest-known domesticated beans in the Americas were found in Guitarrero Cave, an archaeological site in Peru, and dated to around the second millennium BCE. Genetic analyses of the common bean Phaseolus show that it originated in Mesoamerica, and subsequently spread southward, along with maize and squash, traditional companion crops.[9]
Most of the kinds of beans commonly eaten today are part of the genus Phaseolus, which originated in the Americas. The first European to encounter them was Christopher Columbus, while exploring what may have been the Bahamas, and saw them growing in fields. Five kinds of Phaseolus beans were domesticated by pre-Columbian peoples, selecting pods that did not open and scatter their seeds when ripe: common beans (P. vulgaris) grown from Chile to the northern part of the United States; lima and sieva beans (P. lunatus); and the less widely distributed teparies (P. acutifolius), scarlet runner beans (P. coccineus), and polyanthus beans.
Pre-Columbian peoples as far north as the Atlantic seaboard grew beans in the "Three Sisters" method of companion planting. The beans were interplanted with maize and squash.[10] Beans were cultivated across Chile in Pre-Hispanic times, likely as far south as the Chiloé Archipelago.[11]
Most beans are legumes, but from many different genera, native to different regions.[12]
| Species and common varieties | Probable home region | Distribution, climate | Notes | ||
|---|---|---|---|---|---|
| Phaseolus |
| The Americas | Tropical, subtropical, Warm temperate | Some contain high levels of toxic phytohemagglutinin.[13] [14] [15] | |
| Pisum | Mediterranean | Subtropical, temperate, occasionally cool tropical | |||
| Vigna |
| Mostly South Asia | Equatorial, pantropical, warm subtropical, hot temperate | ||
| Cajanus | C. cajan pigeon pea | Indian Subcontinent | Pantropical, equatorial | ||
| Lens | L. culinaris red, green, and Puy lentils | Near East/Levant | Temperate, subtropical, cool tropical | ||
| Cicer | C. arietinum chickpeas | Turkey/Levant/Near East | Temperate, subtropical, cool tropical | ||
| Vicia |
| Near East | Subtropical, temperate | Causes Favism in susceptible people.[16] [17] | |
| Arachis | A. hypogaea peanut | South America | Warm Subtropical, cool tropical | ||
| Glycine | G. max soybean | East Asia | Hot temperate, Subtropical, cool tropical | ||
| Macrotyloma | M. uniflorum horsegram | South Asia | Tropical, subtropical | ||
| Mucuna | M. pruriens velvet bean | Tropical Asia and Africa | Tropical, Warm Subtropical | Contains L-DOPA,[18] and smaller amounts of other psychoactive compounds. Can cause itching and rashes on contact. | |
| Lupinus |
| The Mediterranean, Balkans, Levant (albinus), The Andes (mutabilis) | Subtropical, temperate | Requires soaking to remove toxins.[19] | |
| Ceratonia | C. siliqua carob bean | Mediterranean, Middle East | Subtropical, arid subtropical, hot temperate | ||
| Canavalia |
| South Asia or Africa (C. gladiata), Brazil and South America (C. Ensiformis) | Tropical | ||
| Cyamopsis | C. tetragonoloba guar bean | Africa or South Asia | Tropical, semi-arid | Source of Guar gum | |
| Lablab | L. purpureus hyacinth/lablab bean | South Asia, Indian Subcontinent or Africa | Tropical | ||
| Psophocarpus | P. tetranoglobulus winged bean | New Guinea | Tropical, equatorial | ||
| Clitoria | C. ternatea butterfly pea | Equatorial and Tropical Asia | Tropical, subtropical | Flowers used as a natural food colouring | |
| Lathyrus |
| Balkans, India or Asia | Subtropical | Can cause Lathyrism if used as staple.[20] [21] |
The biodiversity of bean cultivars is threatened by modern plant breeding, which selects a small number of the most productive varieties. Efforts are being made to conserve the germplasm of older varieties in different countries.[22] [23] As of 2023, the Norwegian Svalbard Global Seed Vault holds more than 40,000 accessions of Phaseolus bean species.[24]
Unlike the closely related pea, beans are a summer crop that needs warm temperatures to grow. Legumes are capable of nitrogen fixation and hence need less fertiliser than most plants. Maturity is typically 55–60 days from planting to harvest.[25] As the pods mature, they turn yellow and dry up, and the beans inside change from green to their mature colour. Many beans are vines needing external support, such as "bean cages" or poles. Native Americans customarily grew them along with corn and squash, the tall stalks acting as support for the beans.[26]
More recently, the commercial "bush bean" which does not require support and produces all its pods simultaneously has been developed.[27]
The production data for legumes are published by FAO in three categories:
The following is a summary of FAO data.[28]
| Total pulses (dry) [1726] | 40.78 | 41.63 | 56.23 | 77.57 | 81.80 | 2.01 | Per capita production decreased. (Population grew 2.4×) | |
| Oil crops (dry) | ||||||||
|---|---|---|---|---|---|---|---|---|
| Soybeans [236] | 26.88 | 88.53 | 177.02 | 323.20 | 334.89 | 12.46 | Increase driven by animal feeds and oil. | |
| Groundnuts, with shell [242] | 14.13 | 20.58 | 35.82 | 45.08 | 43.98 | 3.11 | ||
| Fresh vegetables (80–90% water) | ||||||||
| Beans, green [414] | 2.63 | 4.09 | 10.92 | 23.12 | 23.60 | 8.96 | ||
| Peas, green [417] | 3.79 | 5.66 | 12.41 | 19.44 | 19.88 | 5.25 | ||
| Country | 2016 | Share | ||
|---|---|---|---|---|
| Total | 81.80 | 100% | ||
| 1 | India | 17.56 | 21.47% | |
| 2 | Canada | 8.20 | 10.03% | |
| 3 | Myanmar | 6.57 | 8.03% | |
| 4 | China | 4.23 | 5.17% | |
| 5 | Nigeria | 3.09 | 3.78% | |
| 6 | Russia | 2.94 | 3.60% | |
| 7 | Ethiopia | 2.73 | 3.34% | |
| 8 | Brazil | 2.62 | 3.21% | |
| 9 | Australia | 2.52 | 3.09% | |
| 10 | USA | 2.44 | 2.98% | |
| 11 | Niger | 2.06 | 2.51% | |
| 12 | Tanzania | 2.00 | 2.45% | |
| Others | 24.82 | 30.34% |
The world leader in production of dry beans (Phaseolus spp),[31] is India, followed by Myanmar (Burma) and Brazil. In Africa, the most important producer is Tanzania.[32]
| Country | Production (tonnes) | Footnote | |
|---|---|---|---|
| 5,460,000 | FAO figure | ||
| 3,053,012 | Official figure | ||
| 3,035,290 | Aggregated data | ||
| 1,495,180 | Semi-official data | ||
| 1,281,586 | Official figure | ||
| 1,267,648 | FAO figure | ||
| 1,056,071 | Official figure | ||
| 774,366 | FAO figure | ||
| 633,823 | Semi-official data | ||
| 603,980 | Official figure | ||
| World | 27,545,942 | Aggregated data |
Source: UN Food and Agriculture Organization (FAO)[33]
Raw green beans are 90% water, 7% carbohydrates, 2% protein, and contain negligible fat. In a 100g reference serving, raw green beans supply 31 calories of food energy, and are a moderate source (10-19% of the Daily Value, DV) of vitamin C (15% DV) and vitamin B6 (11% DV), with no other micronutrients in significant content (table).
Guar beans are used for their gum, a galactomannan polysaccharide. It is used to thicken and stabilise foods and other products.[34]
See main article: Phytohaemagglutinin and Soybean agglutinin.
Some kinds of raw beans contain a harmful, flavourless toxin: the lectin phytohaemagglutinin, which must be destroyed by cooking. Red kidney beans are particularly toxic, but other types also pose risks of food poisoning. Even small quantities (4 or 5 raw beans) may cause severe stomachache, vomiting, and diarrhea. This risk does not apply to canned beans because they have already been cooked.[35] A recommended method is to boil the beans for at least ten minutes; under-cooked beans may be more toxic than raw beans.[36]
Cooking beans, without bringing them to a boil, in a slow cooker at a temperature well below boiling may not destroy toxins. A case of poisoning by butter beans used to make falafel was reported; the beans were used instead of traditional broad beans or chickpeas, soaked and ground without boiling, made into patties, and shallow fried.[37]
Bean poisoning is not well known in the medical community, and many cases may be misdiagnosed or never reported; figures appear not to be available. In the case of the UK National Poisons Information Service, available only to health professionals, the dangers of beans other than red beans were not flagged .
Fermentation is used in some parts of Africa to improve the nutritional value of beans by removing toxins. Inexpensive fermentation improves the nutritional impact of flour from dry beans and improves digestibility, according to research co-authored by Emire Shimelis, from the Food Engineering Program at Addis Ababa University.[38] Beans are a major source of dietary protein in Kenya, Malawi, Tanzania, Uganda and Zambia.[39]
It is common to make beansprouts by letting some types of bean, often mung beans, germinate in moist and warm conditions; beansprouts may be used as ingredients in cooked dishes, or eaten raw or lightly cooked. There have been many outbreaks of disease from bacterial contamination, often by salmonella, listeria, and Escherichia coli, of beansprouts not thoroughly cooked,[40] some causing significant mortality.[41]
Many types of bean like kidney bean contain significant amounts of antinutrients that inhibit some enzyme processes in the body. Phytic acid, present in beans, interferes with bone growth and interrupts vitamin D metabolism.[42] [43]
Many beans, including broad beans, navy beans, kidney beans and soybeans, contain large sugar molecules, oligosaccharides (particularly raffinose and stachyose). A suitable oligosaccharide-cleaving enzyme is necessary to digest these. As the human digestive tract does not contain such enzymes, consumed oligosaccharides are digested by bacteria in the large intestine, producing gases such as methane, released as flatulence.[44] [45] [46] [47]
Beans have often been thought of as a food of the poor, as small farmers ate grains, vegetables, and got their protein from beans, while the wealthier classes were able to afford meat. European society has what Ken Albala calls "a class-based antagonism" to beans.
Different cultures agree in disliking the flatulence that beans cause, and possess their own seasonings to attempt to remedy it: Mexico uses the herb epazote; India the aromatic resin asafoetida; Germany applies the herb savory; in the Middle East, cumin; and Japan the seaweed kombu. A substance for which there is evidence of effectiveness in reducing flatulence is the enzyme alpha-galactosidase;[48] extracted from the mould fungus Aspergillus niger, it breaks down glycolipids and glycoproteins.[49] [50] The reputation of beans for flatulence is the theme of a children's song "Beans, Beans, the Musical Fruit".[51]
The Mexican jumping bean is a segment of a seed pod occupied by the larva of the moth Cydia saltitans, and sold as a novelty. The pods, of the woody plant Sebastiania pavoniana (in the spurge family), start to jump when warmed in the palm of the hand. Scientists have suggested that the random walk that results may help the larva to find shade and so to survive on hot days.[52]