From Academic Kids

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Rice field

Rice fields on Java
Scientific classification

O. barthii
O. glaberrima
O. latifolia
O. longistaminata
O. punctata
O. rufipogon
O. sativa


ITIS 41975 (http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=41975) 2002-09-22

Rice (genus Oryza) is a plant of the grass family which is a dietary staple of more than half of the world's human population. Rice cultivation is well suited to countries with low labor costs and high rainfall, as it is very labor-intensive to cultivate and requires plenty of water for irrigation. However it can be grown practically anywhere, even on steep hillsides. Rice is the world's third largest crop, behind maize (corn) and wheat. Although its species are native to South Asia and certain parts of Africa, centuries of trade and exportation has made it a commonplace in many cultures.


Rice cultivation

Rice is often grown in paddies — shallow puddles (typically 15 cm depth) carefully controlled to ensure the appropriate water depth. Rice paddies sometimes serve a dual agricultural purpose by also producing edible fish or frogs, a useful source of protein. The farmers take advantage of the rice plant's tolerance to water: the water in the paddies prevents weeds from outgrowing the crop. Once the rice has established dominance of the field, the water can be drained in preparation for harvest. Paddies increase productivity, although rice can also be grown on dry land (including on terraced hillsides) with the help of chemical weed controls.

In some instances, a deepwater strain of rice often called floating rice is grown. This can develop elongated stems capable of coping with water depths exceeding 2 meters (6 feet).

Rice paddies are an important habitat for birds such as herons and warblers, and a wide range of amphibians and snakes. They perform a useful function in controlling insect pests.

Whether it is grown in paddies or on dry land, rice requires a great amount of water compared to other food crops. Rice growing is a controversial practice in some areas, particularly in the United States and Australia, where rice farmers use 7% of the nation's water to generate just 0.02% of GDP. However, in nations that have a periodical rain season and typhoons, rice paddies serve to keep the water supply steady and prevent floods from reaching a dangerous level.

Rice blast, caused by the fungus Magnaporthe grisea is the most significant disease affecting rice cultivation.

Preparation as food

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A handful of rice

The seeds of the rice plant are first milled to remove the outer husks of the grain; this creates brown rice. This process may be continued, removing the germ and the rest of the husk, called bran at this point, creating white rice. The white rice may then be buffed with glucose or talc powder (often called polished rice), parboiled, or processed into flour. The white rice may also be enriched to add nutrients, especially those lost during the milling process. While the cheapest method of enriching involves adding a powdered blend of nutrients that will easily wash off (in the United States, rice which has been so treated requires a label warning against rinsing), more sophisticated methods which apply nutrients directly to the grain and then coat the grain with a water insoluble substance are resistant to washing. While washing is counterproductive for the powder enriched rice, it is absolutely necessary to create a better tasting and better consistency of rice when polished rice (illegal in some countries including the United States) is used.

Rice bran, called nuka in Japan, is a valuable commodity in Asia and is used for many daily needs. It is a moist inner oily layer that is heated to produce a very healthy oil. Another use is to make a kind of pickled vegetable.

The raw rice may be ground into flour for many uses as well, including making many kinds of beverages (see below). Also, rice is generally safe for people on a gluten-free diet.

The processed rice seeds are usually boiled or steamed to make them edible, after which they may be fried in oil, or butter, or beaten in a tub to make mochi.

Rice, like other cereal grains, can be puffed (or popped). This process takes advantage of the grains' moisture content and typically involves heating grain pellets in a special chamber. Further puffing is sometimes accomplished by processing pre-puffed pellets in a low-pressure chamber. By the ideal gas law, one can see that both lowering the local pressure or raising the moisture temperature would result in an increase in volume prior to moisture evaporation, thus resulting in a puffy texture.

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Rice dishes and beverages

See Category:Rice dishes, Wikibooks' Rice Recipes for more information on popular rice dishes.

Beverages made from rice include: amazake, horchata, rice milk, and sake.

A result of the UN:Year of Rice is a new method of preparing rice that gives a complete amino acid profile, including GABA. This method is referred to as GABA Rice.

  • Soak washed brown rice 8-12 hours in body temperature water. Cook and use as normal, but will cook faster due to presoaking.

The reason that this is nutritionally superior is due to initiating the germination process and the enzymes have been activated. Like beans, rice should always be soaked ahead of time anyway. Not only will the rice cook faster, but it will have a much better "chew". Note also that white rice will not work for GABA-method and you don't have to worry about combining your rice with a protein food like beans.

History of rice cultivation

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A stand of rice
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Hiroshige Uragawa ,Rice field in Oki province, view of O-Yama.

Two rice varieties were domesticated: Asian rice Oryza sativa and African rice Oryza glaberrima.

It is believed that common wild rice (Oryza rufipogon Griff.) was the wild ancestor of the Asian cultivated rice Oryza sativa [1] (http://station7.kgw.tu-berlin.de/english/abstracts/ChenW.html). O. sativa is believed to have originated around the foothills of the Himalayas, with O. sativa indica on the Indian side and O. sativa japonica on the Chinese side. It is believed that rice cultivation began simultaneously in many countries over 6500 years ago.

O. sativa was adapted to farming in the Middle East and Mediterranean Europe around 800 B.C. The Moros brought it to Spain when they conquered the country, near 700 A.D. After the middle of the 15th century, rice spread throughout Italy and then France, later propagating to all the continents during the great age of European exploration. In 1694 rice arrived in the South Carolina, probably originating from Madagascar. The Spanish took it to South America at the beginning of the 18th century.

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Planting of rice is a labour intensive process

African rice Oryza glaberrima has been cultivated in Africa for 3500 years. Between 1500 and 800 B.C., the African species (Oryza glaberrima) propagated from its original center, the Delta of Niger River, and extended to Senegal. However, it never developed far from its original region. Its cultivation even declined in favor of the Asian species, possibly brought to the African continent by the Arabians coming from the East Coast from the 7th to the 11th centuries.

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The rice motif on this five-yen coin underscores the importance of the grain to the people of Japan.

Dry-land rice was introduced to Japan circa 1000 BC. Later wet-paddy rice agriculture was brought to Japan by the Yayoi circa 300 BC.

Colonial South Carolina and Georgia grew and amassed great wealth from the slave labor obtained from the Senegambia area of West Africa. At the Port of Charleston, through which 40% of all American slave imports passed, slaves from this region of Africa brought the highest prices, in recognition of their prior knowledge of rice culture, which was put to use on the many rice plantations around Georgetown, Charleston, and Savannah. From the slaves, plantation owners learned how to dike the marshes and periodically flood the fields. At first the rice was milled by hand with wooden paddles, then winnowed in sweetgrass baskets (the making of which was another skill brought by the slaves). The invention of the rice mill increased profitability of the crop, and the addition of water power for the mills in 1787 by millwright Jonathan Lucas was another step forward. Rice culture in southeastern USA became less profitable with the loss of slave labor after the American Civil War, and it finally died out just after the turn of the 20th century.

World Production and Trade

World production of rice has risen steadily from about 200 million tons of paddy rice in 1960 to 600 million tons in 2000. Milled rice is about 68% of paddy rice by weight. In the year 2000, the top three producers were China (31% of world production), India (21%), and Indonesia (9%).

World trade figures are very different, as only about 5-6% of rice produced is traded internationally. The largest three exporting countries are Thailand (26% of world exports), Vietnam (15%), and the United States (11%), while the largest three importers are Indonesia (14%), Bangladesh (4%), and Brazil (3%).

  • all figures from UNCTAD 1998-2002


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American long grain rice

Rice varieties are often classified by their grain shapes. For example, Thai or Siamese Jasmine rice is long-grain and relatively less sticky, as long-grain rice contains less starch than short-grain varieties. Chinese restaurants usually serve long-grain as plain unseasoned steamed rice. Japanese mochi rice and Chinese sticky rice are short-grain. Chinese people use sticky rice which is properly known as "glutinous rice" (despite the fact that no form of rice actually contains gluten) to make zongzi. The Japanese table rice is a short grain non-sticky rice. Japanese sake rice is another kind as well.

Indian rice varieties include long-grained Basmati (grown in the North), medium-grained Patna and short-grained Masoori. One variety used widely in South India, is usually referred to in English as boiled rice or parboiled rice. This is prepared by boiling the rice in large pans immediately after harvesting, often over coconut-shell fires, to kill any fungi or other contaminants. It is then dried, and the husk removed later. It often displays small red speckles, and has a smoky flavour from the fires. This rice is used mainly to make idlis.

Aromatic rices have definite aromas and flavors; the most noted varieties are the aforementioned basmati, and a hybrid of basmati and American long-grain rice sold under the trade name, Texmati (which is a genetically modified patented variety that is creating great controversy), both of which have a mild popcorn-like aroma and flavor. In Indonesia there are also red and black varieties.

High-yield varieties of rice suitable for cultivation in Africa and other dry ecosystems called the new rice for Africa (NERICA) cultivars have been developed. Their cultivation will hopefully improve food security in West Africa.

Scientists are working on so-called golden rice which is genetically modified to produce beta carotene, the precursor to vitamin A. This has generated a great deal of controversy over whether the amount of beta carotene would be significant and whether genetically modified foods are desirable.

Draft genomes for the two commonest rice cultivars, indica and japonica, were published in April 2002. Rice was chosen as a model organism for the biology of grasses because of its relatively small genome (~430 Megabases). As a result rice was the first plant or animal to have its complete genome mapped. Basmati rice is the oldest, common progenitor for most types.

See also


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