peanut
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Peanut ( Arachis hypogaea ) |
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The peanut ( Arachis hypogaea ) is a flowering plant in the subfamily of Schmetterlingsblütler (Faboideae) within the family of the Leguminosae (Fabaceae or Leguminosae). The fruit of the peanut is botanically a legume that are evolutionarily to Nuss changed has. The peanut belongs to the same subfamily as, for example, the pea and bean species. The English common name of the peanut, peanut (in German "pea nut"), indicates its botanical affiliation to the legume family.
The similarity to botanical nuts results from the nature of the seeds: the consistency, the high fat content and the comparatively low proportion of starch . Compared to real nuts, the proportion of omega-3 fatty acids is low. In contrast to most other legumes, however, peanuts can be eaten raw . The allergenic potential is relatively high compared to other foods.
description
Appearance and leaf
The peanut is an annual herbaceous plant . The yellowish hairy to bald stem is independently upright to creeping and between 6 and 80 centimeters, but mostly about 30 centimeters long.
The alternate leaves are arranged in a petiole and a leaf blade. The 3.7 to 10 centimeters long petiole is covered with long, coiled trichomes . The pairs feathery leaf blade has at most two pairs rachis opposite mm with 1 to 10 only briefly stalked pinna leaflet . With a length of 1.1 to 5.9 centimeters and a width of 0.5 to 3.4 centimeters, the ovate-oblong to obovate leaflets are paper-like with a largely rounded base and the end is blunt or sanded with a spike tip. The leaf surfaces, which are covered with long hairs, have about ten lateral nerves on each side of the median nerve. The edge of the leaflets is ciliate. The 2 to 4 centimeters large, membranous, hairy stipules are partially fused with the petiole.
Inflorescence and flower
The flowering period extends from May to August. The lateral inflorescences are reduced to one flower. The lowest of the membranous bracts is 1 to 1.4 centimeters long and 4 to 5 millimeters wide and oval-lanceolate with two tips, the others are similar in size but have two columns.
The sessile, hermaphrodite flowers are zygomorphic and five-fold with a double flower envelope . Of the five membranous, narrow sepals four have grown together to form a 4 to 6 mm thin tube and the fifth is free; they enlarge to the point of fruit formation. The 0.7 to 1.3 centimeter long crown has the typical structure of the butterflies . The five petals are yellow to golden yellow, mostly with red nerves. The extended flag is almost circular and only briefly nailed to the base with a sanded tip. The two free slender wings are elongated to obliquely ovate and eyelet. The beaked, long egg-shaped and inwardly curved boat is shorter than the wings. Of the original ten stamens , one or two are missing. All stamens have grown together. There are two forms of anthers, long and short alternate. The single, initially almost sedentary, elongated carpel usually has two to four, rarely up to six ovules . The base of the carpel, often called gynophor (is wrong , because this comes from the flower axis ) or karpophor (English peg = peg, Spanish clavo = nail), extends to a length of 1 to 20 centimeters and curves downwards after fertilization the loose soil. This is how the fruit gets underground, similar to the ground bean or the Bambara peanut (pea). The quickly ephemeral thin style is relatively long, but shorter than the calyx. The small scar is sparsely haired.
Typical bloom of the petals
The structure, referred to here as the fruit stalk, is the gynophore with the fertilized carpel
The gynophore pushes the young fruit under the earth
Fruit and seeds
The legumes are geocarp, so they are in the ground, hence the name "peanut". Although the peanut is a legume, its fruit behaves differently than the legumes that open ; it remains closed and therefore belongs to the nuts morphologically. The fruit consists of a woody, reticulated, yellow pericarp , more precisely known as the mesocarp. During fruit development in the soil, the exocarp dies first, then the endocarp, which temporarily swells to a storage tissue, but is then compressed into a white, cotton-wool-like layer (the white lining of the peanut shell), so that only the mesocarp remains as a covering. This is also where the name mesocarpnuts comes from . The elongated, curved fruits with a length of 2 to 6 centimeters and a diameter of 1 to 1.5 centimeters contain one to four, rarely up to six seeds and are somewhat constricted between them. These underground fruits do not open on their own. The thick fruit walls have a net-like surface. With a length of 1-2 cm and a diameter of 0.5 to 1 centimeter almost oval, pale brown seeds has two abundant oleaginous seed leaves ( cotyledons ). The fruits ripen between July and September.
The seed coat of the kernels that are ready to be harvested is brown, paper-like and tastes bitter, so it is usually removed before further processing or consumption of the kernels.
Genetics and chromosome set
The number of chromosomes in this tetraploid species is 2n = 40. The size of the genome is estimated at around 2.8 billion base pairs, which is the same as the human genome. The species is allotetraploid, i.e. the hybridization of two closely related but different diploid species. Due to the low genetic variation, the species is assumed to be relatively young. By comparison, the likely parent species are Arachis duranensis and Arachis ipaensis ; these grow in the savannah-like landscapes of the Andes, known as Cerrados , with a pronounced dry season. Using the methods of the molecular clock , its divergence time is estimated to be around 3.5 million years. There is a wild tetraploid clan called Arachis monticola , which is probably con-specific to the cultivated peanut, i.e. it belongs to the same biological species. Wild Arachis hypogaea in the narrower sense, however, have never been found. The genetic structure of the species makes it likely that it goes back to very few or possibly even to a single crossing event with subsequent genome duplication. It is not known whether this occurred in wild populations or already in culture. The oldest peanuts of the species Arachis hypogaea found in archaeological excavations come from the Huarmey Valley in Peru and are around 5000 years old. Other peanut species were collected and cultivated a long time before.
Origin and cultivation
Originally native to the Andes of South America, the cultivation of the peanut has spread throughout the tropics and subtropics since its growing importance as an oil crop.
Archaeologists dated the earliest known finds of peanuts related to human settlement in Peru in 2007 to be 7840 years old; the nuts found there in the floor of a house correspond morphologically to wild species, but come from a region in which no wild species is indigenous. From there the peanut cultivation spread to further parts of South and Mesoamerica , where Spanish conquistadors in the markets of Tenochtitlán on the tlalcacáhuatl ( Nahuatl for "peanut", literally "cocoa bean of the earth"; from this word also come the Spanish and French names for the peanut, cacahuete or cacahuète ) became aware.
The peanut was also grown in Brazil 2000 years ago and was brought from there to Africa as part of the slave trade . Today the peanut is grown in warm areas around the world. The main growing areas are West Africa , China , India , North and South America .
The harvested crops are first dried down in water content from 40 to 5 to 10%. In warm countries this is done outdoors, in moderate climates with artificial heat supply. After drying, the nuts are threshed or broken and, if necessary, peeled off.
Economical meaning
The largest peanut producers
According to the Food and Agriculture Organization (FAO) of the United Nations, around 46 million tons of peanuts (with shell) were produced worldwide in 2018 . The ten largest producers together reaped 81.6% of the world harvest. As the largest producer, China alone came to around 38%.
| rank | country | Quantity (in t ) |
|---|---|---|
| 1 |
 People's Republic of China
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17,332,600 |
| 2 |
 India
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6,695,000 |
| 3 |
 Nigeria
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2,886,987 |
| 4th |
 Sudan
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2,884,000 |
| 5 |
 United States
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2,477,340 |
| 6th |
 Myanmar
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1,599,149 |
| 7th |
 Tanzania
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940.204 |
| 8th |
 Argentina
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921.231 |
| 9 |
 Chad
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921.231 |
| 10 |
 Senegal
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893.940 |
| world | 45.950.900 |
trade
The main exporters of peanuts are India , the USA , Argentina , Brazil and the Netherlands . The combined exports of these five countries account for 72% of total world peanut exports, with the US losing its leading role in exports in recent years.
Although China also produces considerable amounts of peanuts, its share of international trade is small at 6%. The peanuts are mostly used to meet domestic needs.
The main buyers of peanuts are the countries of the European Union , Canada and Japan , which together are responsible for 78% of the world's peanut imports. In the European Union, Cyprus is a peanut producing country. Imports into the EU are mainly used for food such as roasted peanuts or as an ingredient in sweets.
Peanut products
Peanuts are often roasted and salted on the market, also as ingredients in sweets .
The shelled peanuts are usually also roasted; Unroasted peanuts taste like beans, cause gas and do not hold up as well (toxic mold ). In the producing countries, however, they are also eaten cooked.
The processed peanut products are used in a variety of ways in the food industry and also serve as a renewable raw material in the chemical industry, cosmetics and, in significant quantities, as an oil-containing feed additive in agricultural animal fattening.
An important peanut product is peanut oil , which is particularly popular as an edible oil in India and China . It is also used as a herbal remedy. Peanut sauces are common in the kitchens of many countries in Southeast Asia, West Africa and the Netherlands . Other products include peanut butter and peanut flips .
Plumpy'nut is an energy-rich paste made from peanut butter, milk powder, oil and sugar for the treatment of moderate malnutrition in the humanitarian aid sector.
Ingredients and health aspects
Nutritional values
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Ripe peanuts can be eaten raw, roasted, or cooked. The peanut has a high nutritional value with 24% protein content. With 176 mg of magnesium , the peanut is one of the magnesium-rich plant foods , along with cashew nuts . Peanuts can make a valuable contribution to a vegetarian diet in particular . However, peanuts also contain a relatively high amount of phytate , which limits the absorption of the minerals they contain. It is worth mentioning the very high content of semi- essential arginine in peanut products .
Health hazards
A representative study in the United States in 2003 found that approximately 1.2% of the population are allergic to parts of the peanut . This result coincides with another study from 1997. Compared to other foods, the allergenic potential of the peanut is comparatively high. This is due to the high number of peanut allergens .
The symptoms of an acute peanut allergy vary widely, but hives , watery eyes, or difficulty breathing are common. In rare cases, however, the symptoms can be very severe or even trigger anaphylactic shock .
Another problem is that under poor storage conditions, peanuts can be attacked by Aspergillus flavus , a mold that produces toxic aflatoxins in the peanuts. For this reason, strict import controls are in place in both the USA and the European Union.
Peanuts contain lectins , which are said to clump red blood cells and, above a certain amount, can cause discomfort.
Synonyms
Well-known synonyms are: Ashanti arachis or Cameroon nut . There were also the names earth acorn , earth pistachio and mundubi bean . The food dictionary still lists other names: Buren nut , Erdbohne , Java Nut , Kurunuss , Mandubinuss and nutsedge .
literature
- Ren Sa, Alfonso Delgado Salinas: Aeschynomeneae. : Arachis. P. 132 - same text online as printed work , Wu Zheng-yi, Peter H. Raven, Deyuan Hong (eds.): Flora of China. Volume 10: Fabaceae , Science Press and Missouri Botanical Garden Press, Beijing and St. Louis 2010, ISBN 978-1-930723-91-7 . (Section description).
- SI Ali: Papilionaceae in the Flora of Pakistan : Arachis - online. (Section description).
- Walter H. Schuster, Joachim Alkämper, Richard Marquard & Adolf Stählin: Legumes for grain use: Grain legumes of the world , Justus Liebig University Gießen, 1998 .: Joachim Alkämper: The peanut ( Arachis hypogaea ).
- Ingrid and Peter Schönfelder : The new book of medicinal plants. Franckh-Kosmos, Stuttgart 2011, ISBN 978-3-440-12932-6 .
Web links
- Sabine Schmidt: allum.de - Allergy Environment Health : Peanut .
- Arachis hypogaea . In: U. Brunken, M. Schmidt, S. Dressler, T. Janssen, A. Thiombiano, G. Zizka: West African plants - A Photo Guide. Senckenberg Research Institute, Frankfurt am Main 2008.
Individual evidence
- ^ J. Smartt: The Groundnut Crop: A scientific basis for improvement. Springer, 1994, ISBN 978-94-0104315-1 (Reprint), p. 71, restricted preview in the Google book search.
- ↑ H. Brücher: Tropical useful plants. Springer, 1977, ISBN 978-3-662-13238-8 (reprint), p. 159.
- ↑ R. Hegnauer : Chemotaxonomy of plants. Volume XIb-2: Leguminosae Part 3: Papilionoideae , Springer, 2001, ISBN 978-3-0348-9392-3 , p. 510.
- ^ Reinhard Lieberei, Christoph Reisdorff, Wolfgang Franke (founder): Useful plants. 8th edition, Thieme, Stuttgart / New York, 2012, ISBN 978-3-13-530408-3 .
- ^ Arachis hypogaea at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ DJ Bertioli, ACG Araujo, S. Nielen et al .: An Overview of Peanut Genome Structure. In: Nalini Mallikarjuna, Rajeev K Varshney (Ed.): Genetics, Genomics and Breeding of Peanuts. CRC Press, Boca Raton 2014, ISBN 978-1-4822-3837-2 .
- ↑ TD Dillehay, J. Rossen, TC Andres, DE Williams: Preceramic adoption of peanut, squash, and cotton in northern Peru. In: Science. 316 (5833), 2007, pp. 1890-1893. doi: 10.1126 / science.1141395
- ^ A b Crops> Groundnuts, with shell. In: FAO production statistics for 2018. fao.org, accessed on February 6, 2019 .
- ^ Trade> Crops and livestock products> Groundnuts, shelled. In: Official FAO trade statistics for 2017. fao.org, accessed on March 17, 2020 .
- ↑ https://www.deutschlandfunkkultur.de/gefahr-durch-schimmelgifte.993.de.html?dram:article_id=154607 Udo Pollmer: Danger from mold toxins: Why you can't eat peanuts raw , report by Deutschlandfunk from February 19 2012, accessed March 14, 2019
- ↑ Peanuts, all types, dry-roasted, without salt - enter Peanuts in the search mask.
- ↑ Scott H. Safe, Anne Muñoz-Furlong, Hugh A. Sampson: Prevalence of peanut and tree nut allergy in the United States determined by means of a random digit dial telephone surveystar: A 5-year follow-up study . In: Journal of Allergy and Clinical Immunology . tape 112 , no. 6 , December 2002, p. 1203-1207 , doi : 10.1016 / S0091-6749 (03) 02026-8 (English).
- ^ P. Altmeyer: Peanut . In: Encyclopedia of Dermatology, Venereology, Allergology, Environmental Medicine . Springer-Verlag, 2010 ( online ).
- ^ Hugh A. Sampson: Peanut Allergy . In: The New England Journal of Medicine . tape 346 , 2002, pp. 1294-1299 , doi : 10.1056 / NEJMcp012667 .
- ↑ Ruth A. Taber, Harry W. Schroeder: Aflatoxin-producing Potential of Isolates of the Aspergillus flavus-oryzae Group from Peanuts (Arachis hypogaea) . In: Applied and Environmental Microbiology . tape 15 , no. 1 , 1967, p. 140-144 ( abstract ).
- ^ JW Dickens: Aflatoxin control program for peanuts . In: Journal of the American Oil Chemists' Society . tape 54 , no. 3 , p. A225-A228 , doi : 10.1007 / BF02894413 (English).
- ↑ Regulation (EC) No. 1152/2009 of the Commission of November 27, 2009 with special provisions for the importation of certain foods from certain third countries due to the risk of aflatoxin contamination and repealing Decision 2006/504 / EC Text of significance for the EEA . In: Official Journal . L 313, November 28, 2009, p. 40-49 ( online ).
- ↑ a b Waldemar Ternes , Alfred Täufel, Lieselotte Tunger, Martin Zobel (eds.): Food lexicon . 4th, comprehensively revised edition. Behr, Hamburg 2005, ISBN 3-89947-165-2 , pp. 493 .
- ^ Georg August Pritzel , Carl Jessen : The German folk names of plants. New contribution to the German linguistic treasure. Philipp Cohen, Hannover 1882, p. 37, online.