International Starch: Rice

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Rice, common name for about 19 species of annual herbs, of the grass family. Common rice is the only species of importance to human beings. It is native to south-eastern Asia and has been cultivated for more than 7,000 years; evidence of cultivation has been found in eastern China dating from before 5000 BC, and in a cave in northern Thailand from about 6000 BC. It thrives in areas of considerable warmth and moisture and reaches a height of about 1 m (3 ft), with flowers bearing six stamens and a solitary pistil. The fruit, a grain, is produced on a nodding inflorescence (flower cluster) of spikelets at the top of the stalk. When the grain is ripe, rice resembles the oat plant. The white endosperm is enclosed by a layer of bran surrounded by a brown husk.

Rice grains are extensively used as human food; rice constitutes the principal food of half the human race. The bran of the rice grain contains protein and vitamins B complex, E, and K. White rice, which is rice from which the nutritious bran has been removed, is an inferior food. A diet of white rice causes such deficiency diseases as beriberi. Recognition of the nutritional value of the rice bran has led to some increase in the consumption of brown rice, which is the rice grain from which the bran has not been removed.

Rice starch

Rice starch
(Amylum Oryzae):
From 2 to most often 6 microns, seldom up to 10 microns with many agglomerates.

Polished rice contains mainly carbohydrate; small amounts of iodine, iron, magnesium, and phosphorus; and almost negligible amounts of protein and fat. In eastern Asia, starch is sometimes extracted from rice and fermented to produce rice wine. Unlike most other cereals, rice is rarely made into bread; it is generally eaten boiled and flavoured according to custom. Rice grain is not commonly used as feed for farm animals; its by-products, however (meal, bran, or rice polish), are used as feed, especially in rice-growing areas. The straw is also fed to livestock. Rice starch is produced for certain applications and is used for stiffening of clothing.

Rice is cultivated in most countries of eastern Asia. Egypt and the countries of southernmost Europe, the southern United States, and Brazil are other important rice-producing regions. Lowland rice, which is the most commonly grown type, requires an extremely moist soil, either rain-fed or artificially flooded. A few varieties, known as upland rice, do not require flooding. In the rice-growing developing countries, almost all cultivation is performed by hand. In more developed countries much of the work is aided by the use of machinery. Lowland rice is grown in a flooded field, or paddy, which is kept under water during most of the growing season. It is drained only at harvest time. In favourable conditions, rice needs only about three months between sowing and harvesting, and three or even four crops can be harvested annually. Rice mills are usually located near the growing regions. Brown rice is dried and cleaned before it is packed. When white rice is desired, the bran is removed in special machines and care is taken not to break the white kernel. The rice kernels are then polished with glucose and talc in order to enhance their appearance. Rice is classified into three types: short-grain rice, which is no more than 5 mm (3 in) long; medium-grain rice, which is 5 to 6 mm (3 in) long; and long-grain rice, which is 6 to 8 mm (2 in) long. The majority of rice varieties grown in tropical regions are long grain, while most of the varieties of milder climates are short or medium grain.

In the late 1960s, experiments by the International Rice Research Institute produced a variety of rice that promised to increase world output dramatically. Working with dwarf varieties of rice from Taiwan and with disease-resistant, high-yield varieties from other Asian countries, researchers developed a short, vigorous, narrow-leaved rice that yielded more grain and tolerated unfavourable weather better than traditional varieties. The new rice was non-lodging; it did not bend over when ripe and was thus more easily harvested, did not rot because of immersion, and was less subject to rodent damage. Development and testing of new strains and new cultivating procedures continue in an effort to increase world yield.

In the European Economic Community (EEC), about 8 800 t of broken rice are processed annually to about 7 000 t of starch in five to six plants in Belgium, Germany, Italy and the Netherlands (Kempf, 1984). The starch is used exclusively as a human food, largely for baby foods and also in extruded noodles. Egypt, Syria and Thailand also produce rice starch (Re.: FAO).

Scientific classification: Rice makes up the genus Oryza of the family Poaceae (or Gramineae). Common rice is classified as Oryza sativa.