Rice

Oryza sativa, commonly known as Asian rice.

Rice stem cross section magnified 400 times

A: Rice with chaff
B: Brown rice
C:Rice with germ
D: White rice with bran residue
E:Musenmai (Japanese:無洗米), Polished and ready to boil rice, literally, non-wash rice
(1):Chaff
(2):Bran
(3):Bran residue
(4):Cereal germ
(5):Endosperm

Rice is the seed of the monocot plants Oryza sativa (Asian rice) or Oryza glaberrima (African rice). As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in Asia and the West Indies. It is the grain with the third-highest worldwide production, after maize (corn) and wheat, according to data for 2009.^[1]

Since a large portion of maize crops are grown for purposes other than human consumption, rice is the most important grain with regard to human nutrition and caloric intake, providing more than one fifth of the calories consumed worldwide by the human species.^[2]

American long-grain rice plants

There are many varieties of rice and culinary preferences tend to vary regionally. For example in India, there is a saying that grains of rice should be like two brothers, close but not stuck together^{[citation needed]}, while in the Far East there is a preference for softer, stickier varieties. Because of its importance as a staple food, rice has considerable cultural importance. For example, rice is first mentioned in the Yajur Veda and then is frequently referred to in Sanskrit texts.^{[citation needed]} Rice is often directly associated with prosperity and fertility, therefore there is the custom of throwing rice at weddings.^[3]

Rice is normally grown as an annual plant, although in tropical areas it can survive as a perennial and can produce a ratoon crop for up to 30 years.^[4] The rice plant can grow to 1–1.8 m (3.3–5.9 ft) tall, occasionally more depending on the variety and soil fertility. It has long, slender leaves 50–100 cm (20–39 in) long and 2–2.5 cm (0.79–0.98 in) broad. The small wind-pollinated flowers are produced in a branched arching to pendulous inflorescence 30–50 cm (12–20 in) long. The edible seed is a grain (caryopsis) 5–12 mm (0.20–0.47 in) long and 2–3 mm (0.079–0.12 in) thick.

Rice cultivation is well-suited to countries and regions with low labor costs and high rainfall, as it is labor-intensive to cultivate and requires ample water. Rice can be grown practically anywhere, even on a steep hill or mountain. Although its parent species are native to South Asia and certain parts of Africa, centuries of trade and exportation have made it commonplace in many cultures worldwide.

The traditional method for cultivating rice is flooding the fields while, or after, setting the young seedlings. This simple method requires sound planning and servicing of the water damming and channeling, but reduces the growth of less robust weed and pest plants that have no submerged growth state, and deters vermin. While flooding is not mandatory for the cultivation of rice, all other methods of irrigation require higher effort in weed and pest control during growth periods and a different approach for fertilizing the soil.

(The name wild rice is usually used for species of the grass genus Zizania, both wild and domesticated, although the term may also be used for primitive or uncultivated varieties of Oryza.)

[edit] Etymology

First attested in English in the middle of the 13th century, the word rice derives from the Old French ris, which comes from Italian riso, in turn from the Latin oriza, which derives from the Greek ὄρυζα (oruza). The Greek word is the source of all European words (cf. Welsh reis, Ger. Reis, Lith. ryžiai, Serbo-Cr. riza, Pol. ryz, Dutch rijst, Romanian orez).^[5][6][7] Ultimately the original source for those languages is from the Tamil word அரிசி (arisi).^[8][9]

[edit] Preparation as food

Rice broker in 1820s Japan. (36 Views of Mount Fuji Hokusai)

Thresh rice cleaning by a Watermill. (36 Views of Mount Fuji Hokusai)

Transplanting rice seedlings in Java, Indonesia

Removing seedlings from seed beds, the first step along a labour-intensive process of growing rice as seen in Cambodia

The seeds of the rice plant are first milled using a rice huller to remove the chaff (the outer husks of the grain). At this point in the process, the product is called brown rice. The milling may be continued, removing the 'bran', i.e., the rest of the husk and the germ, thereby creating white rice. White rice, which keeps longer, lacks some important nutrients; in a limited diet which does not supplement the rice, brown rice helps to prevent the disease beriberi.

Either by hand or in a rice polisher, white rice may be buffed with glucose or talc powder (often called polished rice, though this term may also refer to white rice in general), parboiled, or processed into flour. White rice may also be enriched by adding 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 apply nutrients directly to the grain, coating the grain with a water insoluble substance which is resistant to washing.

In some countries parboiled rice is popular. Parboiled rice is subjected to a steaming or parboiling process while still a brown ricegrains. This causes nutrients from the outer husk, especially thiamine, to move into the grain itself. The parboil process causes a gelatinisation of the starch in the grains. The grains become less brittle, and the color of the milled grain changes from white to yellow. The rice is then dried, and can then be milled as usual or used as brown rice. Milled parboiled rice is nutritionally superior to standard milled rice. Parboiled rice has an additional benefit in that it does not stick to the pan during cooking, as happens when cooking regular white rice. This type of rice is eaten in parts of India and countries of West Africa are also accustomed to consuming parboiled rice.

Despite the hypothetical health risks of talc (such as stomach cancer),^[10] talc-coated rice remains the norm in some countries due to its attractive shiny appearance, but it has been banned in some, and is no longer widely used in others (such as the United States). Even where talc is not used, glucose, starch, or other coatings may be used to improve the appearance of the grains.

Rice bran, called nuka in Japan, is a valuable commodity in Asia and is used for many daily needs. It is a moist, oily inner layer which is heated to produce oil. It is also used as a pickling bed in making rice bran pickles and Takuan.

Raw rice may be ground into flour for many uses, including making many kinds of beverages such as amazake, horchata, rice milk, and rice wine. Rice flour does not contain gluten and is suitable for people on a gluten-free diet. Rice may also be made into various types of noodles. Raw, wild, or brown rice may also be consumed by raw-foodist or fruitarians if soaked and sprouted (usually 1 week to 30 days); see also Gaba rice below.

Processed rice seeds must be boiled or steamed before eating. Boiled rice may be further fried in cooking oil or butter (known as Fried rice), or beaten in a tub to make mochi.

Rice is a good source of protein and a staple food in many parts of the world, but it is not a complete protein: it does not contain all of the essential amino acids in sufficient amounts for good health, and should be combined with other sources of protein, such as nuts, seeds, beans, fish, or meat.^[11]

Rice, like other cereal grains, can be puffed (or popped). This process takes advantage of the grains' water content and typically involves heating grains in a special chamber. Further puffing is sometimes accomplished by processing pre-puffed pellets in a low-pressure chamber. The ideal gas law means that either lowering the local pressure or raising the water temperature results in an increase in volume prior to water evaporation, resulting in a puffy texture. Bulk raw rice density is about 0.9 g/cm³. It decreases to less than one-tenth that when puffed.

[edit] Cooking

Further information: Steamed rice

There are many varieties of rice; for many purposes the main distinction is between long-, medium-, and short-grain rice. The grains of long-grain rice (high amylose) tend to remain intact after cooking; medium-grain rice (high amylopectin) becomes more sticky. Medium-grain rice is used for sweet dishes, for risotto in Italy and many rice dishes, such as arròs negre, in Spain. A stickier medium-grain rice is used for sushi; the stickiness lets the rice be moulded into a solid shape. Short-grain rice is often used for rice pudding.

Uncooked, polished, white long-grain rice grains

A Pakistani-style Chinese rice dish utilizing the Basmati variety

Rice served along with Indian curry. Note the yellowish tinge in the rice. It is due to the common Indian practice of adding turmeric during cooking.

Unmilled to milled rice, from right to left, brown rice, rice with germ, white rice (Japanese rice)

Black rice – one of several colored varieties of natural rice, rich in anthocyanins and tocols. Image compares white and black rice from Japan.

Rice is cooked by boiling or steaming, and absorbs water during cooking. It can be cooked in just as much water as it absorbs (the absorption method), or in a large quantity of water which is drained before serving (the rapid-boil method).^[12] Electric rice cookers, popular in Asia and Latin America, simplify the process of cooking rice. Rice (or any other grain) is sometimes quickly fried in oil or fat before boiling (for example saffron rice or risotto); this makes the cooked rice less sticky, and is a cooking style commonly called pilaf by American chefs or biryani (Dam-pukhtak) in India, Pakistan, and Iran.

In Arab cuisine, rice is an ingredient of many soups and dishes with fish, poultry, and other types of meat. It is also used to stuff vegetables or is wrapped in grape leaves (dolma). When combined with milk, sugar, and honey, it is used to make desserts. In some regions, such as Tabaristan, bread is made using rice flour. Medieval Islamic texts spoke of medical uses for the plant.^[13]

Rice may also be made into congee (also called rice porridge, fawrclaab, okayu, Xifan, jook, or rice gruel) by adding more water than usual, so that the cooked rice is saturated with water, usually to the point that it disintegrates. Rice porridge is commonly eaten as a breakfast food, and is also a traditional food for the sick.

Rice may be soaked prior to cooking, which saves fuel, decreases cooking time, minimizes exposure to high temperature and thus decreases the stickiness of the rice. For some varieties, soaking improves the texture of the cooked rice by increasing expansion of the grains.

Instant rice differs from parboiled rice in that it is milled, fully cooked and then dried. There is a significant degradation in taste and texture.

A nutritionally superior method of preparing brown rice known as GABA Rice or GBR (Germinated Brown Rice)^[14] may be used. This involves soaking washed brown rice for 20 hours in warm water (38 °C or 100 °F) prior to cooking it. This stimulates germination, which activates various enzymes in the rice. By this method, a result of research carried out for the United Nations International Year of Rice, it is possible to obtain a more complete amino acid profile, including GABA.

Cooked rice can contain Bacillus cereus spores, which produce an emetic toxin when left at 4–60 °C (39–140 °F) NZFSA.govt.nz. When storing cooked rice for use the next day, rapid cooling is advised to reduce the risk of toxin production. One of the enterotoxins produced by bacillus cereus is heat-resistant; reheating contaminated rice kills the bacteria, but does not destroy the toxin already present.

Rice flour and starch often are used in batters and breadings to increase crispiness.

[edit] Nutrients and nutritional importance of rice

Rice is the staple food of over half the world's population. It is the predominant dietary energy source for 17 countries in Asia and the pacific, 9 countries in North and South America and 8 countries in Africa. Rice provides 20 percent of the world’s dietary energy supply, while wheat supplies 19 percent and maize 5 percent.^[15]

A detailed analysis of nutrient content of rice suggests that the nutrition value of rice varies based on a number of factors. It depends on the strain of rice, that is between white, brown, black, red and purple varieties of rice – each prevalent in different part of the world. It also depends on nutrient quality of the soil rice is grown in, whether and how the rice is polished or processed, the manner it is enriched, and how it is prepared before consumption.^[16]

An illustrative comparison between white and brown rice of protein quality, mineral and vitamin quality, carbohydrate and fat quality suggests that neither is complete nutrition source. Between the two, there is a significant difference in fiber content and minor differences in other nutrients.^[17]

Brilliantly colored rice strains such as the purple rice derives its color from anthocyanins and tocols. Scientific studies suggest that these color pigments have antioxidant properties that may be useful to human health. In purple rice bran, hydrophilic antioxidants are in greater quantity and have higher free radical scavenging activity than lipophilic antioxidants. Anthocyanins and γ-tocols in purple rice are largely located in the inner portion of purple rice bran.^[18]

Comparative nutrition studies on red, black and white varieties of rice suggest that pigments in red and black rice varieties may offer nutrition benefits. Red or black rice consumption were found to reduce or retard the progression of atherosclerotic plaque development, induced by dietary cholesterol, in mammals. White rice consumption offered no similar benefits, and the study claims this to be due to absent antioxidants of red and black varieties of rice.^[19]

[edit] Comparison of rice to other major staple foods

The following table shows the nutrient content of major staple foods in a raw form. Raw grains, however, aren't edible and can not be digested. These must be sprouted, or prepared and cooked for human consumption. In sprouted and cooked form, the relative nutritional and anti-nutritional contents of each of these grains is remarkably different from that of raw form of these grains reported in this table.

[edit] Rice growing ecology

Rice can be grown in different environments, depending upon water availability.^[31]

1. Lowland, rainfed, which is drought prone, favors medium depth; waterlogged, submergence, and flood prone
2. Lowland, irrigated, grown in both the wet season and the dry season
3. Deep water or floating rice
4. Coastal Wetland
5. Upland rice, Upland rice is also known as 'Ghaiya rice', well known for its drought tolerance^[32]

[edit] History of domestication and cultivation

[edit] Asia

Terraced rice paddy on a hill slope in Indonesia.

Semi-ripe Paddy in West Bengal, India

The average Asian rice farmer owns a few hectares : Banaue Rice Terraces, N. Luzon, Philippines

Rice field under monsoon clouds in Pegu Division, Burma

Rice crop in Madagascar

Woman drying rice in Bhaktapur

The commonly accepted view is that rice was first domesticated in the region of the Yangtze River valley in China.^[33][34] Morphological studies of rice phytoliths from the Diaotonghuan archaeological site clearly show the transition from the collection of wild rice to the cultivation of domesticated rice. The large number of wild rice phytoliths at the Diaotonghuan level dating from 12,000–11,000 BP indicates that wild rice collection was part of the local means of subsistence. Changes in the morphology of Diaotonghuan phytoliths dating from 10,000–8,000 BP show that rice had by this time been domesticated.^[35] Soon afterwards the two major varieties of Indica and Japonica/Sinica rice were being grown in Central China.^[34] In the late 3rd millennium BC, there was a rapid expansion of rice cultivation into mainland Southeast Asia and westwards across India and Nepal.^[34]

In 2003, Korean archaeologists claimed to have discovered the world's oldest domesticated rice.^[36] Their 15,000 year old age challenges the accepted view that rice cultivation originated in China about 12,000 years ago.^[36] These findings were received by academia with strong skepticism,^[37] and the results and their publicizing has been cited as being driven by a combination of nationalist and regional interests.^[38] In 2011, a combined effort by the Stanford University, New York University, Washington University in St. Louis, and Purdue University has provided the strongest evidence yet that there is only one single origin of domesticated rice, in the Yangtze Valley of China.^[39][40]

The earliest remains of rice in the Indian subcontinent have been found in the Indo-Gangetic Plain and date from 7000–6000 BC though the earliest widely accepted date for cultivated rice is placed at around 3000–2500 BC with findings in regions belonging to the Indus Valley Civilization.^[41] Perennial wild rices still grow in Assam and Nepal. It seems to have appeared around 1400 BC in southern India after its domestication in the northern plains.^{[citation needed]} It then spread to all the fertile alluvial plains watered by rivers. Cultivation and cooking methods are thought to have spread to the west rapidly and by medieval times, southern Europe saw the introduction of rice as a hearty grain.

According to Zohary and Hopf (2000, p. 91), O. sativa was recovered from a grave at Susa in Iran (dated to the 1st century AD) at one end of the ancient world, another domestication of rice in South Asia.

Today, the majority of all rice produced comes from China, India, Indonesia, Pakistan, Bangladesh, Vietnam, Thailand, Myanmar, Philippines, and Japan. Asian farmers still account for 92% of the world's total rice production.

[edit] Companion plant

One of the earliest known examples of companion planting is the growing of rice with Azolla, the mosquito fern, which covers the top of a fresh rice paddy's water, blocking out any competing plants, as well as fixing nitrogen from the atmosphere for the rice to use. The rice is planted when it is tall enough to poke out above the azolla. This method has been used for at least a thousand years.

[edit] Africa

African rice has been cultivated for 3500 years. Between 1500 and 800 BC, Oryza glaberrima propagated from its original centre, the Niger River delta, and extended to Senegal. However, it never developed far from its original region. Its cultivation even declined in favour of the Asian species, possibly brought to the African continent by Arabs coming from the east coast between the 6th and 11th centuries CE. It helped Africa conquer its famine of 1203.^[42]

[edit] Middle East

In Iraq rice was grown in some areas of southern Iraq. With the rise of Islam it moved north to Nisibin, the southern shores of the Caspian Sea and then beyond the Muslim world into the valley of Volga. In Palestine, rice came to be grown in the Jordan Valley. Rice is also grown in Yemen.^[43]

[edit] Europe

The Moors brought Asiatic rice to the Iberian Peninsula in the 10th century. Records indicate it was grown in Valencia and Majorca. In Majorca, rice cultivation seems to have stopped after the Christian conquest, although historians are not certain.^[43]

Muslims also brought rice to Sicily, where it was an important crop^[43] long before it is noted in the plain of Pisa (1468) or in the Lombard plain (1475), where its cultivation was promoted by Ludovico Sforza, Duke of Milan, and demonstrated in his model farms.^[44]

After the 15th century, rice spread throughout Italy and then France, later propagating to all the continents during the age of European exploration.

[edit] Caribbean and Latin America

Rice is not native to the Americas but was introduced to Latin America and the Caribbean by European colonizers at an early date with Spanish colonizers introducing Asian rice to Mexico in the 1520s at Veracruz and the Portuguese and their African slaves introducing it at about the same time to Colonial Brazil.^[45] Recent scholarship suggests that African slaves played an active role in the establishment of rice in the New World and that African rice was an important crop from an early period.^[46] Varieties of rice and bean dishes that were a staple dish along the peoples of West Africa remained a staple among their descendants subjected to slavery in the Spanish New World colonies, Brazil and elsewhere in the Americas.^[42]

The Native Americans of the what is now the Eastern United States may have practiced extensive agriculture with forms of wild rice.

[edit] United States

South Carolina rice plantation (Mansfield Plantation, Georgetown.)

In 1694, rice arrived in South Carolina, probably originating from Madagascar.^[45]

In the United States, colonial South Carolina and Georgia grew and amassed great wealth from the Slavery labor obtained from the Senegambia area of West Africa and from coastal Sierra Leone. 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 enslaved Africans, plantation owners learned how to dyke 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 slaves from Africa). 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 the southeastern U.S. 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. Today, people can visit the only remaining rice plantation in South Carolina that still has the original winnowing barn and rice mill from the mid-19th century at the historic Mansfield Plantation in Georgetown, South Carolina. The predominant strain of rice in the Carolinas was from Africa and was known as Carolina Gold. The cultivar has been preserved and there are current attempts to reintroduce it as a commercially grown crop.^[47]

Rice production by county in the United States, 2010

In the southern United States, rice has been grown in southern Arkansas, Louisiana, and east Texas since the mid-19th century. Many Cajun farmers grew rice in wet marshes and low lying prairies where they could also farm crayfish when the fields were flooded.^[48] In recent years rice production has risen in North America, especially in the Mississippi River Delta areas in the states of Arkansas and Mississippi.

Rice cultivation began in California during the California Gold Rush, when an estimated 40,000 Chinese laborers immigrated to the state and grew small amounts of the grain for their own consumption. However, commercial production began only in 1912 in the town of Richvale in Butte County.^[49] By 2006, California produced the second largest rice crop in the United States,^[50] after Arkansas, with production concentrated in six counties north of Sacramento.^[51] Unlike the Mississippi Delta region, California's production is dominated by short- and medium-grain japonica varieties, including cultivars developed for the local climate such as Calrose, which makes up as much as 85% of the state's crop.^[52]

References to wild rice in the Americas are to the unrelated Zizania palustris

More than 100 varieties of rice are commercially produced primarily in six states (Arkansas, Texas, Louisiana, Mississippi, Missouri, and California) in the U.S.^[53] According to estimates for the 2006 crop year, rice production in the U.S. is valued at $1.88 billion, approximately half of which is expected to be exported. The U.S. provides about 12% of world rice trade.^[53] The majority of domestic utilization of U.S. rice is direct food use (58%), while 16% is used in each of processed foods and beer. The remaining 10% is found in pet food.^[53]

[edit] Australia

Rice was one of the earliest crops planted in Australia by British settlers, who had experience with rice plantations in the Americas and the subcontinent.

Although attempts to grow rice in the well-watered north of Australia have been made for many years, they have consistently failed because of inherent iron and manganese toxicities in the soils and destruction by pests.

In the 1920s it was seen as a possible irrigation crop on soils within the Murray-Darling Basin that were too heavy for the cultivation of fruit and too infertile for wheat.^[54]

Because irrigation water, despite the extremely low runoff of temperate Australia, was (and remains) very cheap, the growing of rice was taken up by agricultural groups over the following decades. Californian varieties of rice were found suitable for the climate in the Riverina, and the first mill opened at Leeton in 1951.

Even before this Australia's rice production greatly exceeded local needs,^[54] and rice exports to Japan have become a major source of foreign currency. Above-average rainfall from the 1950s to the middle 1990s^[55] encouraged the expansion of the Riverina rice industry, but its prodigious water use in a practically waterless region began to attract the attention of environmental scientists. These became severely concerned with declining flow in the Snowy River and the lower Murray River.

Although rice growing in Australia is highly profitable due to the cheapness of land, several recent years of severe drought have led many to call for its elimination because of its effects on extremely fragile aquatic ecosystems. The Australian rice industry is somewhat opportunistic, with the area planted varying significantly from season to season depending on water allocations in the Murray and Murrumbidgee irrigation regions.

[edit] Production and commerce

Worldwide rice production

Production of rice by country — 2007 (million metric ton)[56]
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