Rice is the seed of the grass species Oryza sativa (Asian rice) or less commonly Oryza glaberrima (African rice). The name wild rice is usually used for species of the genera Zizania and Porteresia, both wild and domesticated, although the term may also be used for primitive or uncultivated varieties of Oryza. Rice, a monocot, 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. Rice cultivation is well-suited to countries and regions with low labour costs and high rainfall, as it is labour-intensive to cultivate and requires ample water. However, rice can be grown practically anywhere, even on a steep hill or mountain area with the use of water-controlling terrace systems. Although its parent species are native to Asia and certain parts of Africa, centuries of trade and exportation have made it commonplace in many cultures worldwide. Production and consumption of rice are estimated to have been responsible for 4% of global consumption of crops.
CHARACTERISTICS
The rice plant can grow 1–1.8 m (3–6 ft) tall, occasionally more depending on the variety and soil fertility. It has long, slender leaves; 50–100 cm (20–40 in) long and 2–2.5 cm (3⁄4–1 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 (3⁄16–15⁄32 in) long and 2–3 mm (3⁄32–1⁄8 in) thick.
NUTRITION
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% of the world’s dietary energy supply.
Cooked unenriched long-grain white rice is composed of 68% water, 28% carbohydrates, 3% protein, and negligible fat. A detailed analysis of the nutrient content of rice suggests that the nutrition value of rice varies based on several factors. It depends on the strain of rice, such as white, brown, red, and black (or purple) varieties having different prevalence across world regions. It also depends on the 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.
RICE PROCESSING AND ITS USEFULNESS
The harvested rice kernel, known as paddy, or rough rice, is enclosed by the hull, or husk. Milling usually removes both the hull and bran layers of the kernel, and a coating of glucose and talc is sometimes applied to give the kernel a glossy finish. Rice that is processed to remove only the husks, called brown rice, contains about 8 per cent protein and small amounts of fats and is a source of thiamine, niacin, riboflavin, iron, and calcium. Rice that is milled to remove the bran as well is called white rice and is greatly diminished in nutrients. When white rice forms a major portion of the diet, there is a risk of beriberi, a disease resulting from a deficiency of thiamine and minerals. Parboiled white rice is specially processed before milling to retain most of the nutrients, and enriched rice has iron and B vitamins added to it.
The by-products of milling, including the bran and rice polish (finely powdered bran and starch resulting from polishing), are sometimes used as livestock feed. Oil is processed from the bran for both food and industrial uses. Broken rice is used in brewing, distilling, and the manufacture of starch and rice flour. Hulls are used for fuel, packing material, industrial grinding, fertilizer manufacture, and in the manufacture of an industrial chemical called furfural. The straw is used for feed, livestock bedding, roof thatching, mats, garments, packing material, and broom straws.
As a cereal grain, domesticated rice is the most widely consumed staple food for over half of the world’s human population, especially in Asia and Africa. It is the agricultural commodity with the third-highest worldwide production, after sugarcane and maize. Since sizable portions of sugarcane and maize crops are used for purposes other than human consumption, rice is the most important food crop for human nutrition and caloric intake, providing more than one-fifth of the calories consumed worldwide by humans.
Comments are closed.