Rice

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.

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 (rice, 741.5 million metric tons or 817.4 million short tons in 2014), after sugarcane (1.9 billion metric tons or 2.1 billion short tons) and maize (1.0 billion metric tons or 1.1 billion short tons). Since sizable portions of sugarcane and maize crops are used for purposes other than human consumption, rice is the most important food crop with regard to human nutrition and caloric intake, providing more than one-fifth of the calories consumed worldwide by humans. There are many varieties of rice and culinary preferences tend to vary regionally.

The traditional method for cultivating rice is flooding the fields while, or after, setting the young seedlings. This simple method requires sound irrigation planning 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.

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 labor costs and high rainfall, as it is labor-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.

Characteristics

The rice plant can grow to 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.

Food

Cooking

The varieties of rice are typically classified as long-, medium-, and short-grained. The grains of long-grain rice (high in amylose) tend to remain intact after cooking; medium-grain rice (high in 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. Some varieties of long-grain rice that are high in amylopectin, known as Thai Sticky rice, are usually steamed. A stickier short-grain rice is used for sushi; the stickiness allows rice to hold its shape when cooked. Short-grain rice is used extensively in Japan, including to accompany savoury dishes. Short-grain rice is often used for rice pudding.

Instant rice differs from parboiled rice in that it is fully cooked and then dried, though there is a significant degradation in taste and texture. Rice flour and starch often are used in batters and breadings to increase crispiness.

Preparation

Rinsing rice before cooking removes much of the starch, thereby reducing the extent to which individual grains will stick together. This yields a fluffier rice, whereas not rinsing yields a stickier and creamier result. Rice produced in the US is usually fortified with vitamins and minerals, and rinsing will result in a loss of nutrients.

Rice may be soaked to decrease cooking time, conserve fuel, minimize exposure to high temperature, and reduce stickiness. For some varieties, soaking improves the texture of the cooked rice by increasing expansion of the grains. Rice may be soaked for 30 minutes up to several hours.

Brown rice may be soaked in warm water for 20 hours to stimulate germination. This process, called germinated brown rice (GBR), activates enzymes and enhances amino acids including gamma-aminobutyric acid to improve the nutritional value of brown rice. This method is a result of research carried out for the United Nations International Year of Rice.

Rice is cooked by boiling or steaming, and absorbs water during cooking. With the absorption method, rice may be cooked in a volume of water equal to the volume of dry rice plus any evaporation losses. With the rapid-boil method, rice may be cooked in a large quantity of water which is drained before serving. Rapid-boil preparation is not desirable with enriched rice, as much of the enrichment additives are lost when the water is discarded. 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 in Iran and Afghanistan or biryani in India and Pakistan.

Dishes

In Arab cuisine, rice is an ingredient of many soups and dishes with fish, poultry, and other types of meat. It is 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. Rice may be made into congee (also called rice porridge 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 a traditional food for the sick.

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, while wheat supplies 19% and maize (corn) 5%.

Cooked unenriched long-grain white rice is composed of 68% water, 28% carbohydrates, 3% protein, and negligible fat (table). A 100-gram (3+1⁄2-ounce) reference serving of it provides 540 kilojoules (130 kilocalories) of food energy and contains no micronutrients in significant amounts, with all less than 10% of the Daily Value (DV) (table). Cooked short-grain white rice provides the same food energy and contains moderate amounts of B vitamins, iron, and manganese (10–17% DV) per 100-gram serving (table).

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, such as white, brown, red, and black (or purple) varieties having different prevalence across world regions. 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.

A 2018 World Health Organization (WHO) guideline showed that fortification of rice to reduce malnutrition may involve different micronutrient strategies, including iron only, iron with zinc, vitamin A, and folic acid, or iron with other B-complex vitamins, such as thiamin, niacin, vitamin B6, and pantothenic acid. A systematic review of clinical research on the efficacy of rice fortification showed the strategy had the main effect of reducing the risk of iron deficiency by 35% and increasing blood levels of hemoglobin. The guideline established a major recommendation: “Fortification of rice with iron is recommended as a public health strategy to improve the iron status of populations, in settings where rice is a staple food.”

Rice grown experimentally under elevated carbon dioxide levels, similar to those predicted for the year 2100 as a result of human activity, had less iron, zinc, and protein, as well as lower levels of thiamin, riboflavin, folic acid, and pantothenic acid. The following table shows the nutrient content of rice and other major staple foods in a raw form on a dry weight basis to account for their different water contents.

Nutrient content of 10 major staple foods per 100 g dry weight,

Staple	Maize (corn)	Rice, white	Wheat	Potatoes	Cassava	Soybeans, green	Sweet potatoes	Yams	Sorghum	Plantain	RDA
Water content (%)	10	12	13	79	60	68	77	70	9	65
Raw grams per 100g dry weight	111	114	115	476	250	313	435	333	110	286
Nutrient
Energy (kJ)	1698	1736	1574	1533	1675	1922	1565	1647	1559	1460	8,368–10,460
Protein (g)	10.4	8.1	14.5	9.5	3.5	40.6	7.0	5.0	12.4	3.7	50
Fat (g)	5.3	0.8	1.8	0.4	0.7	21.6	0.2	0.6	3.6	1.1	44–77
Carbohydrates (g)	82	91	82	81	95	34	87	93	82	91	130
Fiber (g)	8.1	1.5	14.0	10.5	4.5	13.1	13.0	13.7	6.9	6.6	30
Sugar (g)	0.7	0.1	0.5	3.7	4.3	0.0	18.2	1.7	0.0	42.9	minimal
Minerals											RDA
Calcium (mg)	8	32	33	57	40	616	130	57	31	9	1,000
Iron (mg)	3.01	0.91	3.67	3.71	0.68	11.09	2.65	1.80	4.84	1.71	8
Magnesium (mg)	141	28	145	110	53	203	109	70	0	106	400
Phosphorus (mg)	233	131	331	271	68	606	204	183	315	97	700
Potassium (mg)	319	131	417	2005	678	1938	1465	2720	385	1426	4700
Sodium (mg)	39	6	2	29	35	47	239	30	7	11	1,500
Zinc (mg)	2.46	1.24	3.05	1.38	0.85	3.09	1.30	0.80	0.00	0.40	11
Copper (mg)	0.34	0.25	0.49	0.52	0.25	0.41	0.65	0.60	–	0.23	0.9
Manganese (mg)	0.54	1.24	4.59	0.71	0.95	1.72	1.13	1.33	–	–	2.3
Selenium (μg)	17.2	17.2	81.3	1.4	1.8	4.7	2.6	2.3	0.0	4.3	55
Vitamins											RDA
Vitamin C (mg)	0.0	0.0	0.0	93.8	51.5	90.6	10.4	57.0	0.0	52.6	90
Thiamin (B1) (mg)	0.43	0.08	0.34	0.38	0.23	1.38	0.35	0.37	0.26	0.14	1.2
Riboflavin (B2) (mg)	0.22	0.06	0.14	0.14	0.13	0.56	0.26	0.10	0.15	0.14	1.3
Niacin (B3) (mg)	4.03	1.82	6.28	5.00	2.13	5.16	2.43	1.83	3.22	1.97	16
Pantothenic acid (B5) (mg)	0.47	1.15	1.09	1.43	0.28	0.47	3.48	1.03	–	0.74	5
Vitamin B6 (mg)	0.69	0.18	0.34	1.43	0.23	0.22	0.91	0.97	–	0.86	1.3
Folate Total (B9) (μg)	21	9	44	76	68	516	48	77	0	63	400
Vitamin A (IU)	238	0	10	10	33	563	4178	460	0	3220	5000
Vitamin E, alpha-tocopherol (mg)	0.54	0.13	1.16	0.05	0.48	0.00	1.13	1.30	0.00	0.40	15
Vitamin K1 (μg)	0.3	0.1	2.2	9.0	4.8	0.0	7.8	8.7	0.0	2.0	120
Beta-carotene (μg)	108	0	6	5	20	0	36996	277	0	1306	10500
Lutein+zeaxanthin (μg)	1506	0	253	38	0	0	0	0	0	86	6000
Fats											RDA
Saturated fatty acids (g)	0.74	0.20	0.30	0.14	0.18	2.47	0.09	0.13	0.51	0.40	minimal
Monounsaturated fatty acids (g)	1.39	0.24	0.23	0.00	0.20	4.00	0.00	0.03	1.09	0.09	22–55
Polyunsaturated fatty acids (g)	2.40	0.20	0.72	0.19	0.13	10.00	0.04	0.27	1.51	0.20	13–19
											RDA

Rice, white, long-grain, regular, unenriched, cooked without salt

Nutritional value per 100 g (3.5 oz)
Energy	130 kcal (540 kJ)
Carbohydrates	28.1 g
Sugars	0.05 g
Dietary fiber	0.4 g
Fat	0.28 g
Protein	2.69 g
Vitamins	Quantity %DV†
Thiamine (B1)	2% 0.02 mg
Riboflavin (B2)	1% 0.013 mg
Niacin (B3)	3% 0.4 mg
Pantothenic acid (B5)	0% 0 mg
Vitamin B6	7% 0.093 mg
Minerals	Quantity %DV†
Calcium	1% 10 mg
Iron	2% 0.2 mg
Magnesium	3% 12 mg
Manganese	0% 0 mg
Phosphorus	6% 43 mg
Potassium	1% 35 mg
Sodium	0% 1 mg
Zinc	1% 0.049 mg
Other constituents	Quantity
Water	68.44 g
Link to USDA Database entry
Units