Maize field ( Zea mays subsp. Mays )
Maize ( Zea mays ), also called kukuruz (from Slavonic ) in parts of Austria and Old Bavaria , is a plant species within the sweet grass family (Poaceae). The cereal originally comes from Mexico and is a monoecious single-sex C 4 plant .
The subspecies (subspecies) Zea mays subsp. mays . In the world grain harvest , maize takes first place with over 1.1 billion tons (2017) ahead of wheat and rice . Over 60 percent of this is processed into corn silage and fed to livestock. In addition, energy maize is used as a renewable raw material for the production of bioethanol and biogas .
The grain maize is one of the staple foods of the people of Africa and Latin America . The gluten-free cereal is also suitable for people who are hypersensitive to gluten ( gluten intolerance , celiac disease ).
The cultivated maize is rich in shapes thanks to its long history of breeding.
Cultivated corn is a strongly built, deciduous, annual , herbaceous plant that can grow to heights of one to three meters. The round, not or only rarely branched stalk is covered over its entire length by smooth leaf sheaths . It is medullary inside and can have a diameter of five centimeters at the base. The numerous nodes are especially close to the ground in close succession. Sprout roots develop from them, which serve to absorb water and nutrients, but above all to ensure the plant's stability.
The leaves are arranged alternately on the stalk. The three to five millimeter long ligule is split or ciliate. The simple, slightly rough, sometimes scattered hairy, dark green leaf blade is up to one meter long and four to ten centimeters wide, flat and wavy towards the edge.
Cultivated maize is single-sexed ( monoecious ). Are the male terminal on the shoot tip rispigen inflorescences , located at the Rispenästen from paired spikelets composed with two male flowers. One to three female inflorescences grow in leaf axils on the lower to middle area of the stalk. These lateral, short-stalked cobs are completely enveloped by bracts (Lieschblätter, also called Lieschen, spoken / ˈliːʃən / ) and carry spikelets in pairs in 8 to 16 longitudinal rows. Each spikelet contains two flowers, but only one of them is fully developed. The ovary is very small with three millimeters, but equipped for anthesis with 20 to 40 centimeters long styluses . Later, the dried-up styles protrude as a brownish bundle from the tip of the piston between the leaf sheaths. Since the outer husks and palea of the female flowers do not develop any further, the fruits can protrude without husks.
The piston-shaped fruit cluster contains corn kernels ( caryopses ) at the ripening period , which depending on the variety can be whitish, golden yellow, red or black-violet, the thousand-grain weight is 250 to 400 grams.
This therophyte is a summer annual plant . The high stalk is supported by sprout roots from the nodes of the stem base. Stem pulp and fruits are at least initially sugary. Stomata are on both sides of the sheet; 95 per square millimeter above, 160 per mm 2 below . Maize is a C4 plant , and malate is the first photosynthetic product here. The C 4 method is an adaptation to very warm and sunny climatic conditions, such as those found in the tropics and subtropics in particular. The CO 2 supply is used in the best possible way. Especially at high temperatures, maize plants can use CO 2 far better for growth than ordinary C 3 plants. They also use less water.
The flowering period extends (in Central Europe) from July to September. From an ecological point of view, it is of the "long-dust thread type". The maize is wind flowering ( anemophilia ), so the female flowers are pollinated by the wind transport of the pollen . The flower is "vormännlich" , this favors cross- pollination . In the case of pre-masculinity (proterandry), the anthers empty the pollen before the stigma of the flower is ready for conception. The style is long and filamentous, so that the pollen has to cover more than 10 cm to the ovule . There are only 10,000 pollen grains per flower, but 18 million per flower head. With a length of 0.1 mm and a weight of 0.00025 mg, the maize pollen is one of the largest and heaviest of the plants that grow here. The pollen is sticky, only covers relatively short distances due to the wind and can only germinate for about a day. The pleasant scent of pollen is also surprising for wind pollination ; in fact, maize is an important source of pollen for honeybees .
The corn pens are poisonous. The main active ingredients in the scars are 0.85% unknown alkaloids . Perhaps aflatoxins are also responsible for the toxicity, because conidia of Aspergillus flavus germinate particularly well on the stigmas of female maize flowers if they are yellow-brown in color and are already covered with pollen . This apparently supplies the necessary nutrients and enables the fungus to form rich conidia. The hyphae then grow through the scar canal to the ovules. Symptoms of poisoning: The alkaloids cause states of excitement, delirium after inhalation, and vomiting, colic and diarrhea after prolonged exposure. The style of the female flower, collected before pollination , is used as a drug . They are smoked by the Indians in Peru as an intoxicant.
The center of maize cultivation is in central Mexico. It is now largely undisputed that the wild grass Teosinte is the wild ancestor of maize. The flowers of teosinte and maize can hardly be distinguished visually, the number of chromosomes in both plants is identical and they hybridize in nature wherever they grow close to each other. However, the fruit stands are clearly different. Teosinte does not form cobs with several rows of grains, but rather two rows of triangular grains sit on a thin axis of the ears. Several of these ears stand together in clusters. When ripe, the grains fall off the ear. The development of today's cultivated maize, which cannot reproduce without human help, is therefore one of the greatest domestication achievements of humans. However, details of the history of domestication are still unclear. In 2008, a team of researchers found that teosinte in the central valley of balsa in southern Mexico was the starting variety. In the Xihuatoxtla there, 8,700 year old traces were found, along with the corresponding tools.
According to recent research corn comes from the Balsas- teosinte from the tropical rainforest of the Rio Balsas from Central Mexico -Beckens. Prehistoric remains of corn have been found in several locations in Mexico, Panama, New Mexico, and Peru since the second half of the 20th century. Corn remains in the valley of Tehuacán were among the first finds . The intact cobs, which no longer had any grains, were between 1.9 and 2.4 centimeters long. They had an average of eight rows of grains with six to nine grains per row. The cultivated maize from the Tehuacán valley was long ascribed an age of around 9,000 years, but according to new 14 C data it only dates from around 4,700 BC. Two corn on the cob from Guila Naquitz, which are less than 5 cm long, were dated 3,300 BC. Dated. Overall, the first fully Neolithic settlements in Mexico date from around 3,500 BC. Chr. (Uncalibrated).
Cultivated maize comes from Trincheras on the Rio Casas Grandes in northern Chihuahua and Las Playas in northern Sonora and dates back to around 1,000 BC. Is dated. Amaranth is also known from Trincheras . The first arable settlements in the southwest lie on the low terraces of rivers. Corn may have been sown here after the spring floods subsided. Since 1,100 BC Smaller irrigation systems are known from the area of Tucson (Arizona). From the Palo Blanco phase, which dates from around 200 BC. Chr. To about 700 AD, pistons with a length of eight to ten centimeters are known, which had between 113 and 163 grains.
16th / 17th century
Corn in Europe
"The maize is the only one of the common types of grain from America." (Johannes Humlum, Zur Geographie des Maisbau 1942)
The discovery of America in 1492 did not bring Christopher Columbus riches and treasures as he had hoped, but instead came across various fruits and plants. Including corn, which came to Europe relatively quickly after 1492 and from here spread all over the world. Columbus describes maize (derived from “mahiz” from the language of the Taíno Arawak Indians on the Caribbean islands) in his diaries as a plant of fundamental importance for food and agriculture on the local islands. In 1503 maize can be found for the first time in the commercial registers of Seville , which at that time had the sole right to goods imported from America.
In the 16th century the “American grain” found its way into the Spanish ornamental gardens. Sources show that corn was grown in Andalusia from 1525 onwards . In the south of the Iberian Peninsula, due to the climate, maize had greater problems with asserting itself against the existing vine, wheat and olive fields. In the north, maize was able to prevail and spread more quickly and, as an inexpensive food, made a significant contribution to the food supply of the financially weaker. From Spain, the maize reached southern Europe and the Middle East .
The maize came to Italy from Spain , but the new growing areas were not the areas under the leadership of Spain, but mainly the area around Venice . In the 16th century, the first sources record the arrival of yellow-grained maize (there are numerous representations, such as the Villa Farnesina in Rome) and the existence of maize plants in gardens in northern Italy. Towards the end of the 17th century, maize production increased more and more and in the 18th century it even overtook that of wheat .
The Italians were the first to recognize the corn kernel’s potential as a field crop. The maize plant does not make great demands in warm summer temperatures and can also be grown without agricultural equipment and also delivers high yields.
The spread in south-eastern Europe can most likely be traced back to military influences. The Balkans were one of Europe's early corn producers. In the 17th century the cultivation of maize gained a foothold in the countries of the Balkans and has become an indispensable staple food in Southeastern Europe.
In Switzerland, maize has been grown in the St. Gallen Rhine Valley since the 17th century , where it thrives particularly well due to the warm and humid climate and the favorable effects of the Alpine foehn . The crop was cultivated in the Rhine Valley mainly as edible maize for consumption and not as fodder maize for cattle as in other arable areas.
At the end of the 16th century, maize also found its way to south-west France, where the conditions for maize cultivation were particularly good around Toulouse . The corn did not come further north at first.
At the time, Venice had close ties to the Spaniards who started their journey to America, which is why Venice received the first samples only a short time after the corn kernel arrived in Spain. The corn kernel set out on its journey to Germany from Venice, because southern Germany and Venice were closely linked by trade. Many German traders lived in Venice, while at the same time the largest Venetian trading post was located in Nuremberg. This is how the corn kernel found its way into Germany, just a few decades after the arrival of Europeans in America. In Germany in the 16th and 17th centuries, maize was only cultivated in gardens in climatically favored regions such as the Rhine region or Baden.
Hieronymus Bock was one of the first to list corn in the "New Kreüterbuch" in 1539. At that time still called Welschkorn:
"Our Germania would soon be called Felix Arabia, because we are so many foreigners of the plants from day to day from foreign countries in our ground and which dz large Welschkorn not the least doubt was first brought to us by merchants from warm, free countries."
Leonhart Fuchs, on the other hand, had the first pictorial representation of a maize plant in the book he published in 1543, while illustrations in Jacob Theodor Tabernaemontanus Neuw Kreuterbuch from 1588 show that in the 16th century the many colors of the grain were known.
Corn in Africa
The Portuguese introduced the grain to Africa at the beginning of the 16th century. The corn kernel quickly spread across the continent and was successfully incorporated into traditional land use systems. At the Gold Coast Ghana corn was from the 16th century until 1850 an important food, on the one hand for long journeys, on the other hand to soldiers in the war. Corn was also used as food for the gods in certain rituals. The Dutchman Pieter de Marees reports in his notes that a kind of beer made from corn, called Poitou , was often drunk . The corn reached the Gold Coast from the Caribbean or America via São Tomé , an uninhabited island in West Africa that was discovered by the Portuguese. From there, the corn then went to the branches on the Gold Coast.
War and the slave trade had a major impact on the corn trade on the Gold Coast. Roasted corn was particularly popular due to its longer shelf life. In addition, the Asante Army used corn kernels to keep track of the soldiers killed. In Accra , maize had become the main crop by the late 17th century, and maize was a symbol of fertility for the Ga tribe . It was used there on the belly of women who were pregnant for the first time.
It can be assumed that the population of the African continent increased considerably, thanks in part to the maize. This development played a role in the slave trade that began around this time.
Development from the garden plant to the arable crop
There is some process for acculturation and use of novel plants. So previously unknown plants were first taken up as medicinal herbs in pre-industrial times , as it was assumed that exotic things had a miraculous effect. The first reports on maize can be found in context as a medicinal product, herbaria from the 16th century also refer to the medicinal properties of this American crop. This did not change until the middle of the 18th century. At the time, maize was considered to be beneficial for digestion. At the same time, voices could be heard who considered the corn to be difficult to digest and warned against it.
Maize developed from a botanical rarity to a generally accepted field crop. In the early to mid-16th century, corn could only be found in small quantities in local vegetable gardens, while a century later, corn played a much more important role. The corn has established itself as a field crop. The high yields from the harvest of maize are one of the main reasons why maize is increasingly found on arable land from the middle of the 17th century. Compared to European cereals, maize survives longer periods of drought or rain better, and maize also impresses with its shorter ripening time. Maize requires more labor, and above all more organic fertilizer, but its yield prospects were higher than those of the other varieties. Especially since the high crop yields could be used to feed the animals that produced the fertilizer.
This also had an impact on the farming population. The population began to consume the corn themselves and to sell the wheat they saved, making corn a financial means. Existing cattle feeding problems were also solved with the help of maize and potatoes . Maize was mainly grown where farmers only had small plots of land; large farmers could not till their fields because the workload was too great.
In the 17th century, the climatic conditions for maize were worse due to a small ice age . As a result, maize cultivation failed in large parts of Europe. That is why maize did not have its first small heyday until the 18th century. With the warming, the cultivation limit later shifted to the north.
From the 18th century
Corn cultivation in Germany
Only after major failures in the potato harvest occurred in 1805 and 1806 due to a plant disease did maize varieties begin to be bred that were suitable for the somewhat more severe central and northern German climate. Even though recipes were published during this time on how maize can be used for soups, pudding, cakes, porridge and as a coffee substitute, maize was mainly used for green fodder production. However, the acreage remained small in the 19th century and amounted to less than one percent in Germany. Only in Baden was the cultivation of maize somewhat more widespread. It was not until the 1970s that varieties adapted to the Central European site conditions were developed, so that maize cultivation expanded significantly here ( Blizzard maize , German Maize Committee , German Maize Club ).
Corn cultivation in Switzerland
In the Swiss region around the Rhine Valley, an independent maize culture has developed, which resulted in two thirds of the Rheintal arable land being used for maize cultivation in the middle of the 19th century. The name Rheintaler Ribelmais , which is an independent variety, has been protected since 2000 with the designation of origin Rheintaler Ribelmais AOP as Switzerland's first grain product . From the Rhine Valley Ribelmais AOP numerous regional products are manufactured, for example, under the registered brand name Ribelgold marketed maize beer a regional brewery Sonnenbräu .
In Austria , especially in Eastern Austria, as well as in some areas in Bavaria near the border (to Austria), maize is also called “Kukuruz” (pronounced gúgarutz in Vienna, Upper and Lower Austria and also in Burgenland). This is from serbokroat. kukuruz borrowed (cf. also Czech. sladká kukuřice ( sweet corn ), Polish. kukurydza , Russian. кукуруза (kukurusa) ; the name was also adopted as kukorica in Hungarian ), the origin of which is unclear and controversial. If originally Slavic, it may have been derived from a call kukuru , which was used to attract chickens to feed, or perhaps from Ottoman-Turk. kokoroz borrowed from Albanian , cf. kokërrëz , from kokërr "globules, pearls, grains" (a connection with the Kuruzen , rebellious Hungarian farmers, is unlikely and probably folk etymology). Other common names are: “Welschkorn” and “Turkish wheat”, in Carinthia, Tyrol and Vorarlberg often also “[der] Türk en” for short , in South Tyrol also known as Tirk, tirg, Tirg, Tirgg, tirgge, tirgn, Türgg, Türk , corn is also called granoturco in Italian . In Styria, “Woaz” means either wheat or maize (“Türk Woaz”) , depending on the region . In Switzerland, the St. Gallen Rhine Valley in particular knows the expression Türgge or Törgge for the light edible corn from which the traditional Riebel is made. These naming does not necessarily have to have something to do with the Turks, but can possibly also be explained as a folk etymology with the origin from the supposed Orient or the “pagan countries”; The same was regionally customary for other imports from the New World. The designations " Welschkorn ", which is particularly common in the Palatinate , and the older French blé d'Inde , which is still common today among French-speaking Canadians , also refer to foreign or overseas origins .
Corn is a summer crop. In Germany, sowing takes place from mid-April to early May, when the soil is warm enough and there is no longer any danger of late frosts. Maize needs a certain temperature to germinate and emerge in the field (germination 7–9 ° C) and a certain amount of heat to emerge. At low temperatures, the seedling is attacked by soil fungi and loses its momentum; The result is patchy maize stocks with lower yields. On the other hand, late sowing also leads to reduced yields because the solar energy in summer is then not fully used. The rule of thumb in Germany is: sowing after May 10th results in a one percent reduction in yield per day of delay.
Maize is sown in rows as precision sowing with mechanical or pneumatic precision seeders (Austrian: set); the stand density depends on the variety and region and averages around 10 (7.5–11) plants / m². The row spacing is around 75 centimeters, the seed spacing around 10 to 20 centimeters.
The harvest of silage maize , usually by forage harvesters , takes place in Germany from mid-September to the beginning of October (the optimal harvest date is around 30% dry matter of the total plant). Grain maize is harvested in climatically preferred areas from the end of September to the end of November. Nevertheless, the moisture content of the grains is around 25-35% so high that appropriate drying is necessary. Single grains with max. 16% moisture; If whole pistons are stored in ventilated wire mesh silos, the humidity may be slightly higher. The hectare yield of grain maize is between 80 and 120 dt / ha when harvested . Grain maize can now be harvested with combine harvesters, whereby a special cutting mechanism (see maize cutting mechanism ) separates the cobs from the stalks and the cobs can be threshed directly by the combine harvester .
Foil seed is widespread in Canada and Ireland . When sowing, the rows are covered with a film to achieve the greenhouse effect . The film is biodegradable and remains on the field. To keep the crop weed-free, a pre-emergence herbicide is applied at the same time .
Additional yields could be achieved especially in cool years. Investigations in the Canadian Newfoundland showed a 9 to 15 day shorter vegetation period, while dry matter yields increased by 14 to 22%. Trials in the Netherlands in 2008 showed that the same seed can be sown two weeks earlier so that higher-yielding varieties can be used. In particular, the availability of phosphorus is significantly improved with the rising soil temperatures under foil. Additional yields were also found under dry conditions. In addition, a maize variety with a 100 point higher maturity number (FAO number) can be grown.
The area performance of the seeder is significantly lower than with conventional devices due to the simultaneous attachment of the film. Depending on the number and arrangement of the holes in the foil, there may be problems with draining water.
Up until the 1930s, only open-flowering maize varieties were cultivated, such as the yellow Baden country maize. Due to significant breeding progress, the cultivation of maize hybrids began in the USA in the 1930s . Thanks to the heterosis effect, hybrid maize brings significantly higher yields than open-flowering varieties; however, a reproduction (seed) of the harvested grains leads to a lower yield. In industrialized countries, farmers usually buy fresh hybrid seeds every year, as the higher costs are offset by the higher yields. This is not always possible for poor farmers in developing countries, so they recycle hybrid seeds. Despite the drop in yield caused by recycling, offspring of hybrids are usually still several generations superior to traditional varieties.
QPM maize ( Quality Protein Maize ) is the name given to maize varieties with an increased content of the essential amino acids lysine and tryptophan , which are limiting in maize . Since corn is the most important source of protein in many African countries due to poor access to animal protein and legumes, QPM has the potential to improve the health of many people. QPM varieties are already grown in around 40 countries, mostly in Africa.
The trade in maize seeds is regulated in the Plant Variety Protection Act and the Seed Traffic Law, compliance with which is regulated by the Federal Plant Variety Office and monitored by the state authorities. The permitted varieties are published periodically in the European List of Varieties . In 2010, corn seed was increased on 3,754 hectares in Germany, almost exclusively on the Upper Rhine in Baden-Württemberg. More than 80% of the seeds required are imported, mainly from France and Hungary.
The varieties that are cultivated worldwide are described with a three-digit maturity number from 100 to 900. Of the nine ripening groups, the 100 to 300 varieties ripen with less solar energy in northern Germany than silage maize and in southern Germany as grain maize. The high yield potential of the maturity groups higher than 400 requires high solar energy, which can only be achieved in regions up to the 40th degree of latitude on earth, e.g. B. in the west of the USA or south of Rome .Up until 1998, maize varieties were classified based on their FAO number . Only the dry matter content of the flask was determined. A differentiation according to use (silage maize or grain maize) was therefore not possible for technical reasons. A difference of ten FAO units under Central European conditions represented a ripening difference of one to two days or 1 to 2% in the dry matter content of the grains at the time of ripening.
Today, the number of maturities is specified specifically for use, i.e. H. For silage manure types (S), the DM content of the entire plant is used as a criterion, and for grain maize types (K), the DM content of the grains is taken into account,
example: S 230 / K 240
The new classifications are relative classifications to reference varieties. Thus, a variety would appear in different groups according to the FAO number and the usage-specific maturity number .
Genetically modified varieties
Since the late 1990s , pest- resistant and herbicide-resistant maize varieties produced using genetic engineering have been grown. In 2009 the cultivation took place in 16 countries. The most important growing countries are the USA, Brazil , Argentina and Canada . In the USA, the proportion of transgenic varieties is 85%. According to peer-reviewed studies, the cultivation of transgenic maize is more cost-saving and / or more productive and more environmentally friendly in the countries examined. Other studies come to a different conclusion, in that they found, for example, higher pesticide consumption over a longer observation period. In North America, possible influences on the biodiversity of wild relatives of the maize in Mexico are being investigated.
Corn is defined in part by the shape, composition, and use of the corn kernels. The shape of the grain is determined by the nutrient tissue. The following classification is common (English designations in brackets):
- Hard corn ( English flint = pebble, flint, flat, round). The ripe grains are round because there is starch-rich nutrient tissue here, but horn-like around them. Hard corn is the most widely grown form of corn in the United States.
- Tooth corn ( dent ). The ripe grains have sunk in the middle because the protein layer (also called horn endosperm) runs around the grain. Most varieties in European cultivation are tooth corn / hard corn mixed types.
- Popcorn ( popcorn ). The entire nutrient tissue is horn-like. The grains burst when heated.
- Sweet corn ( sweet corn ). Since sweet corn species lack a gene, the sugar does not turn into starch when it ripens. The grains shrink accordingly when ripe. Sweet corn is usually harvested and eaten before the ripening process is complete. There are numerous special color varieties such as blue corn and purple corn .
- Starch corn ( flour corn ). The grains have no horn endosperm (protein layer), but only a soft and starchy nutrient tissue and can therefore be ground into flour better than other maize groups. Grains and cobs of this form of maize can be found in the graves of the Incas and Aztecs , among others .
- Waxy corn ( waxy corn ). The grains look waxy because they are coated with amylopectin .
- Pod corn ( pod corn ). The form of maize is no longer of any agricultural significance today. Since each grain is surrounded by husks, processing is limited.
Alternatively, varieties of corn can be grouped according to their age.
Diseases and pests
The diseases of cultivated maize include emergence diseases , seedling, root, stem and cob rot , maize blight ( Ustilago maydis ), maize rust ( Puccinia sorghi , P. mayidis ), leaf spot disease ( Helminthosporium sp. ).
In sub-Saharan Africa , the maize streak virus is the most devastating viral disease in maize. The large corn borer ( Prostephanus truncatus ) , which was imported from Mesoamerica, has spread throughout almost all of Africa and sometimes causes considerable damage to maize in the field or in the warehouse. The Aspergillus flavus mold attacks stored maize and may form the highly toxic aflatoxins , which make the harvest unsuitable for human or animal consumption.
As animal pests of cultivated maize are slugs ( Deroceras ssp.) , Wireworm ( Agriotes lineatus ), frit fly ( Oscinella frit ), European corn borer ( Ostrinia nubilalis ), western corn rootworm ( Diabrotica vigifera ), cotton bollworm ( Helicoverpa zea ), Helicoverpa armigera ( Helicoverpa armigera ). The European corn borer ( Ostrinia nubilalis ) bores into the inside of the stem or the cob and thereby destroys large parts of the harvest.
The bacterium Paenibacillus brasilensis often lives in association with maize. Like other Paenibacillus species, it is able to bind nitrogen from the air by fixing nitrogen. This fixation of nitrogen is also known as diazotrophy and is advantageous for the plant, as it receives additional nitrogen in the form of ammonia and higher-quality compounds, which it would not have taken from the air at all and only in the locally typical amount from the soil can.
Worldwide, the hectare yields for grain maize in 2017 were 57.5 dt / ha and in Germany 105.3 dt / ha.
According to the Federal Statistical Office , a total of 4.4 million tons of grain maize (including Corn-Cob-Mix ) were grown on 430,000 hectares in Germany in 2016 . 2.1 million hectares were used for silage maize production (including Lieschkolben), from which 96.6 million tons of silage maize were harvested.
The largest corn producers
According to the food and agriculture organization FAO, around 1.15 billion tons of grain maize were harvested from 194 million hectares worldwide. The following table gives an overview of the 20 largest producers of corn worldwide, who produced a total of 88.8% of the total. This table also contains the figures for Germany, Austria and Switzerland for comparison:
(in t )
|2||People's Republic of China||257.173.900||14th||Nigeria||10.155.027|
- List of the largest agricultural producers
- List of the largest grain producers
- The largest rye producers
- The largest barley producers
- The largest rice producers
- The largest wheat producers
- The largest oat producers
After wheat, maize is the second most traded grain. Globally, around 124 million tons were exported in 2013, of which around 21.4% came from Brazil, followed by the United States (19.5%) and Argentina (16.2%). The largest importer in 2013 was Japan (12.0%), followed by South Korea, Mexico, Egypt and Spain. Other European countries were also among the 20 largest export nations: Hungary, Germany and Poland. Sub-Saharan Africa is largely self-sufficient.
About 15% of the global corn harvest is used as food (period: 2005–2007). Globally, 63% of the corn consumed is fed to livestock, 11% is processed, 10% is used for other purposes, 1% as seed. In developing countries, food accounts for 25% of the demand for corn, in East and South Africa it is 73%, while in industrialized countries it is 3%. In industrialized countries, 23% of the corn consumed is processed, mainly into bioenergy. The demand for corn as feed (especially for pigs and poultry) is increasing by 6% annually, especially due to the increasing consumption of meat in Asia.
For around 900 million people, mainly in Africa and Latin America, corn is the most important staple food. Corn supplies 61% in Central America, 45% in East and South Africa, 29% in the Andean region (Bolivia, Colombia, Ecuador, Guyana, Peru, Suriname and Venezuela), 21% in West and Central Africa and 4% in Asia Energy absorbed by food (see: physiological calorific value ).
Most of the maize grown in Germany is used for fodder purposes ( silage maize , grain maize). A smaller but rapidly growing proportion is used to generate energy in biogas plants (energy maize). The rest is used as food in the form of grain maize and is largely processed in the food industry. These grains are then processed either in dry milling (flours and semolina) or in wet milling (starch) into products such as corn starch (by-product corn gluten; protein-rich animal feed) and corn flour or corn grits (by-products corn germ and husks). These products are used to make glucose syrup , corn oil , corn flakes , popcorn , polenta , peanut flips , tortillas and the like. v. m. In addition to yellow maize, which is widely grown in Europe, there are also red and blue varieties that can add interesting color effects to food.
Use as a medicinal plant
Corn starch and refined corn oil serve as remedies. The oil contains glycerides of linoleic acid (40–60%), oleic acid (25–35%) and palmitic acid (9–12%), vitamin E , and phytosterols . Corn starch serves as a powder base with a high water absorption capacity and as an auxiliary in pharmaceutical technology, e.g. B. in tablet production. At the same time, it is also the starting material for other products such as sorbitol and dextrin . Corn oil is used in skin and body care products and as a carrier solution for oily injections. With the high content of linoleic acid and vitamin E, corn oil is a valuable edible oil.
Average composition (whole grain)
The composition of maize naturally fluctuates, both depending on the environmental conditions (soil, climate) and the cultivation technique (fertilization, plant protection).
1 mg = 1000 µg
In countries where corn is rarely eaten, the corn is simply ground up. Where maize is a daily staple food, the grains are cooked for many hours with alkaline substances (such as slaked lime or wood ash ), husked, ground wet to a dough, then either processed directly into the end product or dried again and traded as flour; Through this process, the contained niacin is usable for the body and taste and baking properties are improved. This processing technique, known as Nixtamalization, was demonstrably used in Oaxaca as early as 1500 BC. Used and may be considerably older. The flour obtained in this way is called Hominy Grits in the southern United States and Masa Harina in Mexico . When maize was introduced into Europe by the Spanish in the 16th century, nixtamalization was not adopted, so that the deficiency disease pellagra also spread in Europe. The connection between corn and the disease has not been recognized for a long time. Pellagra also appeared in West Africa , where corn only became popular as a staple food in the last few centuries.
Another important product is the corn oil obtained from the corn seedlings , which is mainly used as salad oil.
Renewable raw material
In addition to the aforementioned areas of application in nutrition and as animal feed, maize is also used in a variety of ways as a renewable raw material. There are both energetic and material uses that are primarily based on corn starch. Of central importance is its use as an energy crop for the production of biofuels ( bioethanol , especially in North America) and as energy maize for the production of maize silage as a biogas substrate. Energy maize refers to maize that is used to generate energy in biogas plants; The 2009 version of the Renewable Energy Sources Act (EEG) promoted biogas production from renewable raw materials and thus expanded maize cultivation. With the EEG amendment in 2012, the use of maize in new and existing plants was restricted for the first time ("maize lid") in order to counteract this development. Further restrictions followed in the 2017 EEG amendment; the use of corn and grain gradually up to max. 44% in 2021.
In terms of material use, corn starch plays a role as a starting product for bio-based plastics , especially for the fermentative production of lactic acid as a starting product for polylactides (PLA) and for extruded corn starch (e.g. for edible dishes and as compostable filling material in packaging). Like wheat starch and molasses , maize starch can also be used as a fermentation raw material for a number of other fine chemicals, especially antibiotics and amino acids . The cobs produced as a by-product can also be used as raw material for the extraction of furfural .
Based on corn cob granules is oil binder produced. The piston spindles of special hard corn varieties are carved in the USA and used as simple tobacco pipes ("Missouri meerschaum") and are also available in Europe in tobacco shops. Corn coals can also be made from corn cobs by charring and used as charcoal .
Problems of corn cultivation and use
In Germany there is criticism of the strong cultivation of maize for animal feed and the production of agro-fuel and biogas. In particular, it is criticized that maize monocultures (a "cornification of the landscape") have negative effects on the diversity of species ( biodiversity ). For developing countries, the displacement of the nutritionally more valuable millet food, which is common in semi-arid areas, is viewed critically by corn food. Here the change in eating habits is assumed to be the reason.
Extensive maize cultivation promotes shelter and feed sources for wild boar cattle .
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