History
The ''Arachis'' genus is endemic to South America. Cultivated peanuts (''A. hypogaea'') arose from a between two wild species of peanut, thought to be ' and '. The initial hybrid would have been sterile, but spontaneous doubling restored its fertility, forming what is termed an or . Genetic analysis suggests the hybridization may have occurred only once and gave rise to ', a wild form of peanut that occurs in a few limited locations in northwestern , or in southeastern , where the peanut s with the most wild-like features are grown today. and by to ''A. hypogaea''. The process of domestication through artificial selection made ''A. hypogaea'' dramatically different from its wild relatives. The domesticated plants are bushier and more compact, and have a different pod structure and larger seeds. From this primary , cultivation spread and formed secondary and tertiary in , , , , and . Over time, thousands of peanut landraces evolved; these are classified into six botanical varieties and two subspecies (as listed in the peanut scientific classification table). Subspecies ''A. h. fastigiata'' types are more upright in their growth habit and have shorter crop cycles. Subspecies ''A. h. hypogaea'' types spread more on the ground and have longer crop cycles. The oldest known remains of pods have been dated at about 7,600 years old, possibly a wild species that was in cultivation, or ''A. hypogaea'' in the early phase of domestication. They were found in Peru, where dry climatic conditions are favorable for the preservation of organic material. Almost certainly, peanut cultivation antedated this at the center of origin where the climate is moister. Many cultures, such as the , depicted peanuts in their art. Cultivation was well-established in Mesoamerica before the Spanish arrived. There, the s found the (the plant's name) being offered for sale in the marketplace of . The peanut was later spread worldwide by European traders, and cultivation is now widespread in tropical and subtropical regions. In , it substantially replaced a crop plant from the same family, the , whose seed pods also develop underground. In Asia, it became an agricultural mainstay and this region is now the largest producer in the world. In the , peanut growing is most important in the . It was mainly a garden crop for much of the , before shifting to mostly stock until human consumption grew in the 1930s.Putnam, D.H., et al. (1991University of Wisconsin-Extension Cooperative Extension: Alternative Field Crops Manual. The initiated a program to encourage agricultural production and human consumption of peanuts in the late 19th and early 20th centuries. was developed in the 1880s and 1890s in the United States and Canada.
Botany
The peanut is an plant growing tall. As a legume, it belongs to the botanical (also known as , and commonly known as the legume, bean, or pea family). Like most other legumes, peanuts harbor bacteria in their s.
The are and with four leaflets (two opposite pairs; no terminal leaflet); each leaflet is long and across. Like those of many other legumes, the leaves are ; that is, they have "sleep" movements, closing at night.
The flowers are across, and yellowish orange with reddish veining. They are borne in clusters on the stems above ground, and last for just one day. The ovary is located at the base of what appears to be the flower stem, but is actually a highly elongated .
Peanut fruits develop underground, an unusual feature known as . After , a short stalk at the base of the ovary (often termed a , but which actually appears to be part of the ovary itself) elongates to form a thread-like structure known as a "peg". This peg grows down into the soil, allowing the fruit to develop underground. These pods (technically called legumes) are long, normally containing one to four s. The shell of the peanut fruit consists primarily mesocarp with several large veins traversing its length.
Parts
Parts of the peanut include: * - outer covering, in contact with dirt * s (two) - main edible part * - brown paper-like covering of the edible part * - embryonic root at the bottom of the cotyledon, which can be snapped off * - embryonic shoot emerging from the top of the radicleCultivation
Peanuts grow best in light, sandy soil with a pH of 5.9–7. Their capacity to fix nitrogen means that, providing they nodulate properly, peanuts benefit little or not at all from nitrogen-containing , and they improve . Therefore, they are valuable in s. Also, the yield of the peanut crop itself is increased in rotations, through reduced diseases, pests and weeds. For example, in , peanuts in a three-year rotation with corn yield 50% more than nonrotated peanuts. Adequate levels of phosphorus, potassium, calcium, magnesium, and micronutrients are also necessary for good yields.Baughman, Todd; Grichar, James; Black, Mark; Woodward, Jason; Porter, Pat; New, Leon; Baumann, Paul; McFarland, MarkTexas Peanut Production Guide
(PDF). . Retrieved October 16, 2015 To develop well, peanuts need warm weather throughout the growing season. They can be grown with as little as of water, but for best yields need at least . Depending on growing conditions and the cultivar of peanut, harvest is usually 90 to 130 days after planting for subspecies ''A. h. fastigiata'' types, and 120 to 150 days after planting for subspecies ''A. h. hypogaea'' types. Subspecies ''A. h. hypogaea'' types yield more, and are usually preferred where the growing seasons are sufficiently long. Peanut plants continue to produce flowers when pods are developing; therefore even when they are ready for harvest, some pods are immature. In order to maximize yield, the timing of harvest is important. If it is too early, too many pods will be unripe; if too late, the pods will snap off at the stalk, and will remain in the soil. For harvesting, the entire plant, including most of the roots, is removed from the soil. The pods are covered with a network of raised veins and are constricted between seeds. The main yield limiting factors in semiarid regions are drought and high temperature stress. The stages of reproductive development prior to flowering, at flowering and at early pod development, are particularly sensitive to these constraints. Apart from N, P and K, other nutrient deficiencies causing significant yield losses are Ca, Fe and B. Biotic stresses mainly include pests, diseases and weeds. Among insects pests pod borers, aphids and mites are of importance. The most important diseases are leaf spots, rusts and the toxin-producing fungus Aspergillus. Harvesting occurs in two stages. In mechanized systems, a machine is used to cut off the main root of the peanut plant by cutting through the soil just below the level of the peanut pods. The machine lifts the "bush" from the ground and shakes it, then inverts the bush, leaving the plant upside down on the ground to keep the peanuts out of the soil. This allows the peanuts to dry slowly to a little less than a third of their original moisture level over a period of three to four days. Traditionally, peanuts were pulled and inverted by hand. After the peanuts have dried sufficiently, they are , removing the peanut pods from the rest of the bush. It is particularly important that peanuts are dried properly and stored in dry conditions. If they are too high in moisture, or if storage conditions are poor, they may become infected by the '. Many strains of this fungus release and highly ic substances called s.
Cultivars in the United States
There are many peanut s grown around the world. The market classes grown in the United States are Spanish, Runner, Virginia, and Valencia. Peanut production in the United States is divided into three major areas: the southeastern United States region which includes Alabama, Georgia, and Florida; the southwestern United States region which includes , , and Texas; and the third region in the general eastern United States which includes Virginia, North Carolina, and South Carolina. In Georgia, is responsible for developing the breeding program of peanuts resulting in a harvest almost five times greater. Certain cultivar groups are preferred for particular characteristics, such as differences in flavor, oil content, size, shape, and resistance. Most peanuts marketed in the shell are of the Virginia type, along with some Valencias selected for large size and the attractive appearance of the shell. Spanish peanuts are used mostly for peanut candy, salted nuts, and .Spanish group
The small Spanish types are grown in South Africa, and in the southwestern and southeastern United States. Until 1940, 90% of the peanuts grown in the were Spanish types, but the trend since then has been larger-seeded, higher-yielding, more -resistant cultivars. Spanish peanuts have a higher oil content than other types of peanuts. In the United States, the Spanish group is primarily grown in New Mexico, Oklahoma, and Texas. Cultivars of the Spanish group include 'Dixie Spanish', 'Improved Spanish 2B', 'GFA Spanish', 'Argentine', 'Spantex', 'Spanette', 'Shaffers Spanish', 'Natal Common (Spanish)', "White Kernel Varieties', 'Starr', 'Comet', 'Florispan', 'Spanhoma', 'Spancross', 'OLin', 'Tamspan 90', 'AT 9899–14', 'Spanco', 'Wilco I', 'GG 2', 'GG 4', 'TMV 2', and 'Tamnut 06'.Runner group
Since 1940, the southeastern US region has seen a shift to production of Runner group peanuts. This shift is due to good flavor, better roasting characteristics and higher yields when compared to Spanish types, leading to food manufacturers' preference for the use in peanut butter and salted nuts. Georgia's production is now almost 100% Runner type. Cultivars of Runners include 'Southeastern Runner 56-15', 'Dixie Runner', 'Early Runner', 'Virginia Bunch 67', 'Bradford Runner', 'Egyptian Giant' (also known as 'Virginia Bunch' and 'Giant'), 'Rhodesian Spanish Bunch' (Valencia and Virginia Bunch), 'North Carolina Runner 56-15', 'Florunner', 'Virugard', 'Georgia Green', 'Tamrun 96', 'Flavor Runner 458', 'Tamrun OL01', 'Tamrun OL02' 'AT-120', 'Andru-93', 'Southern Runner', 'AT1-1', 'Georgia Brown', 'GK-7', and 'AT-108'.Virginia group
The large-seeded Virginia group peanuts are grown in the US states of Virginia, North Carolina, Tennessee, Texas, New Mexico, Oklahoma, and parts of Georgia. They are increasing in popularity due to demand for large peanuts for processing, particularly for salting, confections, and roasting in the shells. Virginia group peanuts are either bunch or running in growth habit. The bunch type is upright to spreading. It attains a height of , and a spread of , with rows that seldom cover the ground. The pods are borne within of the base of the plant. Cultivars of Virginia type peanuts include 'NC 7', 'NC 9', 'NC 10C', 'NC-V 11', 'VA 93B', 'NC 12C', 'VA-C 92R', 'Gregory', 'VA 98R', 'Perry', 'Wilson, 'Hull', 'AT VC-2' and' Shulamit'.Valencia group
Valencia group peanuts are coarse, and they have heavy reddish stems and large foliage. In the United States, large commercial production is primarily in the of , and in eastern New Mexico near and south of , but they are grown on a small scale elsewhere in the South as the best-flavored and preferred type for . They are comparatively tall, reaching a height of and a spread of . Peanut pods are borne on pegs arising from the main stem and the side branches. Most of the pods are clustered around the base of the plant, and only a few are found several inches away. Valencia types are three- to five-seeded and smooth, with no constriction of the shell between the seeds. Seeds are oval and tightly crowded into the pods. Typical seed weight is 0.4 to 0.5 g. This type is used heavily for sale roasted and salted in-shell peanuts, and for peanut butter. Varieties include 'Valencia A' and 'Valencia C'.Tennessee Red and Tennessee White groups
These are alike, except for the color of the seed. Sometimes known also as Texas Red or White, the plants are similar to Valencia types, except the stems are green to greenish brown, and the pods are rough, irregular, and have a smaller proportion of kernels.Production
In 2019, world production of peanuts (reported as groundnuts in shells) was 49 million s, a 7% increase over 2018 production. China had 36% of global production, followed by India (14%) (table). Other significant producers were , , and the United States.Food
Whole peanuts
Dry-roasting peanuts is a common form of preparation. Dry peanuts can be roasted in the shell or shelled in a home oven if spread out one layer deep in a pan and baked at a temperature of for 15 to 20 min (shelled) and 20 to 25 min (in shell).
are a popular snack in India, China, West Africa, and the southern United States. In the US South, boiled peanuts are often prepared in briny water, and sold in streetside stands.
A distinction can be drawn between raw and green peanuts. A green peanut is a term to describe farm fresh harvested peanuts that have not been dehydrated. They are available from grocery stores, food distributors and farmers markets, during the growing season. Raw peanuts are also uncooked but have been dried/dehydrated and must be rehydrated before boiling (usually in a bowl full of water overnight). Once rehydrated, the raw peanuts are ready to be boiled.
Peanut oil
is often used in cooking, because it has a mild flavor and a relatively high . Due to its high content, it is considered more healthful than , and is resistant to . The several types of peanut oil include aromatic roasted peanut oil, refined peanut oil, extra virgin or cold-pressed peanut oil, and peanut extract. In the United States, refined peanut oil is exempt from allergen labeling laws.Peanut butter
Peanut butter is a food or made from peanuts. It often contains additional ingredients that modify the taste or texture, such as salt, sweeteners or s. Peanut butter is served as a spread on bread, toast or crackers, and used to make sandwiches (notably the ). It is also used in a number of confections, such as peanut-flavored s or croissants and other pastries. The United States is a leading exporter of peanut butter, and itself consumes $800 million of peanut butter annually.Peanut flour
is used in gluten-free cooking.Peanut proteins
Peanut protein concentrates and isolates are commercially produced from defatted peanut flour using several methods. Peanut flour concentrates (about 70% protein) are produced from kernels by removing most of the oil and the water-soluble, non-protein components. , , , and pre-pressing followed by solvent extraction may be used for oil removal, after which protein isolation and purification are implemented.Cuisine
Latin America
Peanuts are particularly common in and , both of which marry indigenous and European ingredients. For instance, in Peru, a popular traditional dish is ''picante de cuy'', a roasted served in a sauce of ground peanuts (ingredients native to South America) with roasted onions and garlic (ingredients from European cuisine). Also, in the Peruvian city of , a dish called ''ocopa'' consists of a smooth sauce of roasted peanuts and (both native to the region) with roasted onions, garlic, and oil, poured over meat or potatoes. Another example is a combining a similar mixture with sautéed seafood or boiled and shredded chicken. These dishes are generally known as ''ajíes'', meaning "hot peppers", such as ''ají de pollo'' and ''ají de mariscos'' (seafood ''ajíes'' may omit peanuts). In Mexico it is also used to prepare different traditional dishes, such as chicken in peanut sauce (''encacahuatado'') and is used as a main ingredient for the preparation of other famous dishes such as red , and oaxacan . Likewise, during colonial times in Peru, the Spanish used peanuts to replace nuts unavailable locally, but used extensively in , such as almonds and pine nuts, typically ground or as paste mixed with rice, meats, and vegetables for dishes like . Throughout the region, many candies and snacks are made using peanuts. In Mexico, it is common to find them in different presentations as a snack or candy: salty, "Japanese" peanuts, praline, ''enchilados'' or in the form of a traditional sweet made with peanuts and honey called ''palanqueta'', and even as peanut .West Asia
Crunchy coated peanuts, called ''kabukim'' in Hebrew, are a popular snack in . ''Kabukim'' are commonly sold by weight at corner stores where fresh nuts and seeds are sold, though they are also available packaged. The coating typically consists of flour, salt, starch, lecithin, and sometimes sesame seeds. The origin of the name is obscure (it may be derived from ''kabuk'' which means nutshell or husk in Turkish). An additional variety of crunchy coated peanuts popular in Israel is "American peanuts". The coating of this variety is thinner, but harder to crack. puffs are a popular snack in Israel. Their shape is similar to , but they are made of peanuts and corn.Southeast Asia
Peanuts are also widely used in n cuisine, such as in , , and , where they are typically made into a spicy . Peanuts originally came to Indonesia from the , where the legume derived from Mexico in times of Spanish colonization. One Philippine dish using peanuts is ', a mixture of meat and peanut butter. Apart from being used in dishes, fried shelled peanuts are a common inexpensive snack in the Philippines with the peanuts commonly served plain salted with garlic chips and variants including adobo and chilli flavors.
Common Indonesian peanut-based dishes include ', ', ', and ', vegetable salads mixed with peanut sauce, and the peanut-based sauce, '.
Indian subcontinent
In the , peanuts are a light snack, usually roasted and salted (sometimes with the addition of ), and often sold roasted in pods or boiled with salt. They are also made into or sweet snack of by processing with refined sugar and . Indian cuisine uses roasted, crushed peanuts to give a crunchy body to salads; they are added whole (without pods) to leafy vegetable stews for the same reason. Another use is for cooking. Most Indians use , , and peanut oil for cooking. In , groundnut is eaten with ''dosa'' and ''idli'' as breakfast. Peanuts are also used in sweets and savory items in South India and also as a flavor in is known for its sweet peanut or , which is also used in savory and sweet mixtures, such as .West Africa
Peanuts grow well in southern and adjacent regions of the , , , , and ; peanuts are similar in both agricultural and culinary qualities to the native to the region, and West Africans have adopted the crop as a staple. , prepared with onions, garlic, peanut butter/paste, and vegetables such as carrots, cabbage, and cauliflower, can be vegetarian (the peanuts supplying ample protein) or prepared with meat, usually chicken. Peanuts are used in the meat stew '. In , peanut butter is used for ''nkate nkwan''.Ghanaian cuisine Crushed peanuts may also be used for peanut candies ''nkate cake'' and ', as well as other local foods such as . Peanut butter is an ingredient in Nigeria's "African salad". Peanut powder is an important ingredient in the spicy coating for s in and .East Africa
Peanuts are a common ingredient of several types of relishes (dishes which accompany ') eaten in and in the eastern part of , and these dishes are common throughout both countries. Thick peanut butter sauces are also made in to serve with rice and other starchy foods. Groundnut , called ''ebinyebwa'' in -speaking areas of , is made by boiling peanut flour with other ingredients, such as , s, dried fish, meat or other vegetables. Across East Africa, roasted peanuts, often in cones of newspaper, are obtained from s.North America
In Canada and the United States, peanuts are used in candies, cakes, cookies, and other sweets. Individually, they are eaten with or without salt. Ninety-five percent of Canadians eat peanuts or peanut butter, with average consumption of of peanuts per person annually, and 79% of Canadians consume peanut butter weekly. In the United States, peanuts and peanut butter are central to American dietary practices, and are typically considered as s. Peanut butter is a common peanut-based food, representing half of American total peanut consumption and $850 million in annual retail sales. is found on restaurant menus in the southeastern states. In some southern portions of the US, peanuts are boiled for several hours until soft and moist. Peanuts are also , sometimes within the shell. Per person, Americans eat of peanut products annually, spending a total of $2 billion in peanut retail purchases.Malnutrition
Peanuts are used to help fight . , MANA Nutrition, and Medika Mamba are high-protein, high-energy, and high-nutrient peanut-based pastes developed to be used as therapeutic food to aid in . The , , Project Peanut Butter, and have used these products to help save malnourished children in . Peanuts can be used like other legumes and grains to make a -free, -like beverage, , which is promoted in Africa as a way to reduce malnutrition among children.Animal feed
Peanut plant tops and crop residues can be used for .Heuzé V., Thiollet H., Tran G., Lebas F., 2017. Peanut forage. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/695 The protein cake (oilcake meal) residue from oil processing is used as an animal feed and as a soil fertilizer. Groundnut cake is a livestock feed, mostly used by cattle as protein supplements. It is one of the most important and valuable feed for all types of livestocks and one of the most active ingredient for poultry rations. Poor storage of the cake may sometimes result in its contamination by , a naturally occurring that is produced by ' and '. The major constituents of the cake are essential s such as and . Other components are crude fiber, crude protein, and fat. Some peanuts can also be fed whole to livestock, for example those in excess of the peanut quota in the US, or those with a higher aflatoxin content than that permitted by the food regulations. Peanut processing often requires dehulling: the hulls generated in large amounts by the peanut industries can then be used to feed livestock, particularly ruminants.Industrial use
Peanuts have a variety of industrial end uses. Paint, varnish, lubricating oil, leather dressings, furniture polish, insecticides, and are made from peanut oil. Soap is made from oil, and many cosmetics contain peanut oil and its derivatives. The protein portion is used in the manufacture of some textile fibers. Peanut shells are used in the manufacture of plastic, wallboard, abrasives, fuel, cellulose (used in and paper), and (glue).Nutritional value
Peanuts are rich in (right table, USDA nutrient data). In a reference serving, peanuts provide of and are an excellent source (defined as more than 20% of the , DV) of several , , several , such as (95% DV), (52% DV) and (48% DV), and (right table). They also contain about 25 g of protein per 100 g serving, a higher proportion than in many . Some studies show that regular consumption of peanuts is associated with a lower specific risk of from certain diseases. However, the do not allow to be inferred. According to the US , "Scientific evidence suggests but does not prove that eating 1.5 ounces per day of most nuts (such as peanuts) as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease." Ranked second after soya beans, peanuts are the world's largest source of vegetable oil. They are the main constituent of margarine and are produced commercially as salad and cooking oil.Phytochemicals
Peanuts contain , and s, s and in amounts similar to several tree nuts. Peanut skins contain which is under preliminary research for its potential effects in humans.Oil composition
A common and oil, peanut oil is 46% monounsaturated fats (primarily ), 32% s (primarily ), and 17% saturated fats (primarily ). Extractable from whole peanuts using a simple water and method, the oil is being considered by 's program for future long-duration human .Health concerns
Allergies
Some people (0.6% of the United States population) report that they experience to peanut exposure; symptoms are specifically severe for this nut, and can range from watery eyes to , which is generally fatal if untreated. Eating a small amount of peanut can cause a reaction. Because of their widespread use in prepared and packaged foods, the avoidance of peanuts can be difficult. The reading of ingredients and warnings on product packaging is necessary to avoid this allergen. Foods that are processed in facilities which also handle peanuts on the same equipment as other foods are required to carry such warnings on their labels. Avoiding cross contamination with peanuts and peanut products, (along with other severe allergens like shellfish) is a promoted and common practice which chefs and restaurants worldwide are becoming aware of. The of allergy states that a lack of early childhood exposure to infectious agents like germs and parasites could be causing the increase of food allergies. Studies comparing age of peanut introduction in Great Britain with introduction in Israel showed that delaying exposure to peanuts in childhood can dramatically increase the risk of developing peanut allergies. Peanut allergy has been associated with the use of skin preparations containing peanut oil among children, but the evidence is not regarded as conclusive. Peanut allergies have also been associated with family history and intake of soy products. Some s in the United States and elsewhere have banned peanuts. However, the efficacy of the bans in reducing allergic reactions is uncertain. A recent study in Canada has shown that there is no difference in the percentage of accidental exposures occurring in schools prohibiting peanuts than in schools allowing them. Refined peanut oil will not cause allergic reactions in most people with peanut allergies. However, crude (unrefined) peanut oils have been shown to contain protein, which may cause allergic reactions. In a randomized, , 60 people with proven peanut allergy were challenged with both crude peanut oil and refined peanut oil. The authors concluded, "Crude peanut oil caused allergic reactions in 10% of allergic subjects studied and should continue to be avoided." They also stated, "Refined peanut oil does not seem to pose a risk to most people with peanut allergy." However, they point out that refined peanut oil can still pose a risk to peanut-allergic individuals if oil that has previously been used to cook foods containing peanuts is reused.Contamination with aflatoxin
If peanut plants are subjected to severe drought during pod formation, or if pods are not properly stored, they may become contaminated with the ' which may produce substances called . Lower-quality peanuts, particularly where mold is evident, are more likely to be contaminated. The tests every truckload of raw peanuts for aflatoxin; any containing aflatoxin levels of more than 15 parts per billion are destroyed. The peanut industry has manufacturing steps in place to ensure all peanuts are inspected for aflatoxin. Peanuts tested to have high aflatoxin are used to make peanut oil where the mold can be removed.Gallery
See also
* * * * * * * * * * * , a failure started in 1951 *References
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