Cereal

Acerealis agrasscultivated for its ediblegrain. Cereals are the world's largest crops, and are thereforestaple foods. They includerice,wheat,rye,oats,barley,millet, andmaize. Edible grains from other plant families, such asbuckwheatandquinoa, arepseudocereals. Most cereals areannuals, producing one crop from each planting, though rice is sometimes grown as aperennial. Winter varieties are hardy enough to be planted in the autumn, becoming dormant in the winter, and harvested in spring or early summer; spring varieties are planted in spring and harvested in late summer. The term cereal is derived from the name of theRoman goddessof grain crops and fertility,Ceres.
Cereals weredomesticatedin theNeolithic, some 8,000 years ago.Wheatandbarleywere domesticated in theFertile Crescent;ricewas domesticated in East Asia, andsorghumandmilletwere domesticated in West Africa. Maize was domesticated byIndigenous peoples of the Americasin southern Mexico about 9,000 years ago. In the 20th century, cereal productivity was greatly increased by theGreen Revolution. This increase in production has accompanied agrowing international trade, with some countries producing large portions of the cereal supply for other countries.
Cereals provide food eaten directly aswhole grains, usually cooked, or they are ground toflourand made intobread,porridge, and other products. Cereals have a highstarchcontent, enabling them to be fermented intoalcoholic drinkssuch asbeer. Cereal farming has a substantialenvironmental impact, and is often produced in high-intensitymonocultures. The environmental harms can be mitigated bysustainable practiceswhich reduce the impact on soil and improve biodiversity, such asno-till farmingandintercropping.
Wheat, barley,rye, andoatswere gathered and eaten in theFertile Crescentduring the earlyNeolithic. Cereal grains 19,000 years old have been found at theOhalo IIsite inIsrael, with charred remnants of wild wheat and barley.
During the same period, farmers inChinabegan tofarm riceand millet, using human-made floods andfiresas part of their cultivation regimen.The use ofsoil conditioners, includingmanure, fish,compostandashes, appears to have begun early, and developed independently in areas of the world includingMesopotamia, theNile Valley, and Eastern Asia.
Cereals that becamemodern barley and wheat weredomesticatedsome 8,000 years ago in the Fertile Crescent.Millets and rice were domesticated in East Asia, whilesorghumand other millets were domesticated in sub-Saharan West Africa, primarily as feed for livestock.Maizearose from a single domestication inMesoamericaabout 9,000 years ago.
In these agricultural regions, religion was often shaped by the divinity associated with the grain and harvests. In the Mesopotamian creation myth, an era of civilization is inaugurated by the grain goddessAshnan.The Roman goddessCerespresided over agriculture, grain crops, fertility, and motherhood;the term cereal is derived from Latincerealis, "of grain", originally meaning "of [the goddess] Ceres".Several gods of antiquity combined agriculture and war: the HittiteSun goddess of Arinna, the CanaaniteLahmuand the RomanJanus.
Complexcivilizationsarose where cereal agriculture created a surplus, allowing for part of the harvest to be appropriated from farmers, allowing power to be concentrated in cities.
During the second half of the 20th century, there was a significant increase in the production of high-yield cereal crops worldwide, especially wheat and rice, due to theGreen Revolution, a technological change funded by development organizations.The strategies developed by the Green Revolution, including mechanized tilling,monoculture, nitrogen fertilizers, and breeding of new strains of seeds. These innovations focused on fending off starvation and increasing yield-per-plant, and were very successful in raising overall yields of cereal grains, but paid less attention to nutritional quality.These modern high-yield cereal crops tend to havelow-quality proteins, withessential amino aciddeficiencies, are high incarbohydrates, and lack balancedessential fatty acids,vitamins,mineralsand other quality factors.So-calledancient grainsandheirloom varietieshave seen an increase in popularity with the"organic" movementsof the early 21st century, but there is a tradeoff in yield-per-plant, putting pressure on resource-poor areas asfood cropsare replaced withcash crops.
Cereals are grasses, in thePoaceaefamily, that produce ediblegrains. A cereal grain is botanically acaryopsis, afruitwhere theseed coatis fused with thepericarp.Grasses havestemsthat are hollow except at thenodesand narrow alternate leaves borne in two ranks.The lower part of each leaf encloses the stem, forming a leaf-sheath. The leaf grows from the base of the blade, an adaptation that protects the growing meristem from grazing animals.The flowers are usuallyhermaphroditic, with the exception ofmaize, and mainlyanemophilousor wind-pollinated, although insects occasionally play a role.
Among the best-known cereals are maize,rice, wheat, barley,sorghum,millet, oat, rye andtriticale.Some other grains are colloquially called cereals, even though they are not grasses; thesepseudocerealsincludebuckwheat,quinoa, andamaranth.
All cereal crops are cultivated in a similar way. Most areannual, so after sowing they are harvested just once.An exception is rice, which although usually treated as an annual can survive as aperennial, producing aratooncrop.Cereals adapted to atemperate climate, such asbarley,oats,rye,spelt,triticale, andwheat, are called cool-season cereals. Those preferring atropical climate, such asmilletandsorghum, are called warm-season cereals.Cool-season cereals, especially rye, followed by barley, are hardy; they grow best in fairly cool weather, and stop growing, depending on variety, when the temperature goes above around 30 °C or 85 °F. Warm-season cereals, in contrast, require hot weather and cannot tolerate frost.Cool-season cereals can be grown in highlands in the tropics, where they sometimes deliver several crops in a single year.
In the tropics, warm-season cereals can be grown at any time of the year. In temperate zones, these cereals can only be grown when there is no frost. Most cereals are planted intilled soils, which reduces weeds and breaks up the surface of a field. Most cereals need regular water in the early part of their life cycle.  Rice is commonly grown in flooded fields,though some strains are grown on dry land.Other warm climate cereals, such as sorghum, are adapted to arid conditions.
Cool-season cereals are grown mainly in temperate zones. These cereals often have both winter varieties for autumn sowing, winter dormancy, and early summer harvesting, and spring varieties planted in spring and harvested in late summer. Winter varieties have the advantage of using water when it is plentiful, and permitting a second crop after the early harvest. They flower only in spring as they requirevernalization, exposure to cold for a specific period, fixed genetically. Spring crops grow when it is warmer but less rainy, so they may need irrigation.
Cereal strains are bred for consistency and resilience to the local environmental conditions. The greatest constraints onyieldareplant diseases, especiallyrusts(mostly thePucciniaspp.) andpowdery mildews.Fusarium head blight, caused byFusarium graminearum, is a significant limitation on a wide variety of cereals.Other pressures includepest insectsand wildlife like rodents and deer.In conventional agriculture, some farmers will applyfungicidesor pesticides
Annual cereals die when they have come to seed, and dry up. Harvesting begins once the plants and seeds are dry enough. Harvesting in mechanized agricultural systems is bycombine harvester, a machine which drives across the field in a single pass in which it cuts the stalks and thenthreshesandwinnowsthe grain.In traditional agricultural systems, mostly in theGlobal South, harvesting may be by hand, using tools such asscythesandgrain cradles.Leftover parts of the plant can be allowed to decompose, or collected asstraw; this can be used for animal bedding, mulch, and a growing medium for mushrooms.It is used in crafts such as building withcoborstraw-bale construction.
If cereals are not completely dry when harvested, such as when the weather is rainy, the stored grain will be spoilt bymouldfungi such asAspergillusandPenicillium.This can be prevented by drying it artificially. It may then be stored in agrain elevatororsilo, to be sold later. Grain stores need to be constructed to protect the grain from damage by pests such as seed-eating birds androdents.
When the cereal is ready to be distributed, it is sold to a manufacturing facility that first removes the outer layers of the grain for subsequentmilling for flouror other processing steps, to produce foods such as flour,oatmeal, orpearl barley.In developing countries, processing may be traditional, in artisanal workshops, as withtortilla productionin Central America.
Most cereals can be processed in a variety of ways.Rice processing, for instance, can create whole-grain or polished rice, or rice flour. Removal of the germ increases the longevity of grain in storage.Some grains can bemalted, a process of activating enzymes in the seed to cause sprouting that turns the complex starches into sugars before drying.These sugars can be extracted for industrial uses and further processing, such as for makingindustrial alcohol,beer,whisky,orrice wine,or solddirectly as a sugar.In the 20th century,industrial processesdeveloped around chemically altering the grain, to be used for other processes. In particular,maizecan be altered to produce food additives, such ascorn starchandhigh-fructose corn syrup.
Cereal production has a substantial impact on the environment.Tillagecan lead tosoil erosionand increased runoff.Irrigation consumes large quantities of water; its extraction from lakes, rivers, oraquifersmay havemultiple environmental effects, such as lowering thewater tableand cause salination of aquifers.Fertilizerproduction contributes toglobal warming,and its use can lead to pollution andeutrophicationof waterways.Arable farming uses large amounts offossil fuel,releasing greenhouse gaseswhich contribute to global warming.Pesticide usage can cause harm to wildlife, such asto bees.
Some of the impacts of growing cereals can be mitigated by changing production practices. Tillage can be reduced byno-till farming, such as by direct drilling of cereal seeds, or by developing and plantingperennial cropvarieties so that annual tilling is not required. Rice can be grown as aratooncrop;and other researchers are exploring perennial cool-season cereals, such askernza, being developed in the US.
Fertilizer and pesticide usage may be reduced in somepolycultures, growing several crops in a single field at the same time.Fossil fuel-basednitrogen fertilizerusage can be reduced byintercroppingcereals withlegumeswhichfix nitrogen.Greenhouse gas emissions may be cut further by more efficient irrigation or by water harvesting methods likecontour trenchingthat reduce the need for irrigation, and by breeding new crop varieties.
Some cereals such as rice require little preparation before human consumption. For example, to make plaincooked rice, rawmilled riceis washed and boiled.Foods such asporridgeandmueslimay be made largely of whole cereals, especially oats, whereas commercialbreakfast cerealssuch asgranolamay be highly processed and combined with sugars,oils, and other products.
Cereals can begroundto make flour.Wheat flouris the main ingredient ofbreadandpasta.Maize flour has been important inMesoamericasince ancient times, with foods such as Mexicantortillasandtamales.Rye flour is a constituent of bread in central and northern Europe,whilerice flouris common in Asia.
A cereal grain consists of starchyendosperm,germ, andbran. Wholemeal flour contains all of these; white flour is without some or all of the germ or bran.
Because cereals have a high starch content, they are often used to makeindustrial alcoholandalcoholic drinksbyfermentation. For instance,beeris produced bybrewingand fermentingstarch, mainly from cereal grains—most commonlymaltedbarley.Rice winessuch as Japanesesakeare brewed in Asia;a fermented rice and honey wine was made in China some 9,000 years ago.
Cereals and their related byproducts such ashayare routinelyfed to farm animals. Common cereals as animal food include maize, barley, wheat, and oats. Moist grains may be treated chemically or made intosilage; mechanically flattened or crimped, and kept in airtight storage until used; or stored dry with a moisture content of less than 14%.Commercially, grains are often combined with other materials and formed into feed pellets.
Aswhole grains, cereals providecarbohydrates,polyunsaturated fats,protein,vitamins, andminerals. When processed by the removal of the bran and germ, all that remains is the starchy endosperm.In somedeveloping countries, cereals constitute a majority of daily sustenance. Indeveloped countries, cereal consumption is moderate and varied but still substantial, primarily in the form of refined and processed grains.
Some cereals are deficient in the essential amino acidlysine, obliging vegetarian cultures to combine their diet of cereal grains withlegumesto obtain a balanced diet. Many legumes, however, are deficient in the essential amino acidmethionine, which grains contain. Thus,a combinationof legumes with grains forms a well-balanced diet for vegetarians. Such combinations includedal(lentils) with rice bySouth IndiansandBengalis,beanswithmaize tortillas,tofuwith rice, andpeanut butterwith wholegrain wheat bread (as sandwiches) in several other cultures, including the Americas.Forfeeding animals, the amount ofcrude proteinmeasured in grains is expressed as grain crude protein concentration.
Cereals constitute the world's largest commodities by tonnage, whether measured by productionor by international trade. Several major producers of cereals dominate the market.Because of the scale of the trade, some countries have become reliant on imports, thus cerealspricingor availability can have outsized impacts on countries with a food trade imbalance and thusfood security.Speculation, as well as other compounding production and supply factors leading up to the2007–2008 financial crises, created rapid inflation of grain prices during the2007–2008 world food price crisis.Other disruptions, such as climate change or war related changes to supply or transportation can create further food insecurity; for example theRussian invasion of Ukrainein 2022 disrupted Ukrainian and Russian wheat supplies causing aglobal food price crisis in 2022that affected countries heavily dependent on wheat flour.
Cereals are the world's largest crops by tonnage of grain produced.Three cereals, maize, wheat, and rice, together accounted for 89% of all cereal production worldwide in 2012, and 43% of the global supply offood energyin 2009,while the production of oats and rye has drastically fallen from their 1960s levels.
Other cereals not included in the U.N.'sFood and Agriculture Organizationstatistics includewild rice, which is grown in small amounts in North America, andteff, an ancient grain that is a staple inEthiopia.Teff is grown in sub-Saharan Africa as a grass primarily for feeding horses. It is high in fiber and protein. Its flour is often used to makeinjera. It can be eaten as a warm breakfast cereal likefarinawith a chocolate or nutty flavor.
The table shows the annual production of cereals in 1961, 1980, 2000, 2010, and 2019/2020.
Cereals are the most tradedcommoditiesby quantity in 2021, with wheat, maize, and rice the main cereals involved. The Americas and Europe are the largest exporters, and Asia is the largest importer.The largest exporter of maize is the US, while India is the largest exporter of rice. China is the largest importer of maize and of rice. Many other countries trade cereals, both as exporters and as importers.Cereals aretraded as futureson worldcommodity markets, helping to mitigate the risks of changes in price for example, if harvests fail.