Rice is the most important food crop of the developing world and the staple food of more than half of the world's population. Rich in nutrients and vitamins and minerals, it an excellent source of complex carbohydrates. Nine out of every ten people in the world who eat rice are Asian. In Africa, rice is the fastest growing staple – and it is also growing in popularity in Latin America and the Caribbean.
Rice, wheat, and maize are the world’s three leading food crops; together they directly supply more than 42% of all calories consumed by the entire human population. Human consumption in 2009 accounted for 78% of total production for rice, compared with 64% for wheat and 14% for maize. Of these three major crops, rice is by far the most important food crop for people in low- and lower-middle-income countries. Although rice consumption is spread across income classes relatively equally in low-income countries, the poorest people consume relatively little wheat.
Every rice grain (or seed) consists of the rice enclosed in a hull. The rice itself mainly comprises the embryo (or germ) and the starchy endosperm, but it also has a surface formed of several thin layers of differentiated tissues, collectively known as the bran layer, which forms 5% to 8% of grain weight.
There are many different types of rice with many different qualities to suit different consumer preferences. Quality factors relate to grain length, stickiness, aroma, texture, and flavor. Nutritional content may also vary between different types of rice.
Oryza sativa, or Asian rice, contains two broad groups: indica (long-grain) and japonica (short-grain). Other types of Asian rice include glutinous rice and aromatic rice. Oryza glaberrima, or African rice, includes long- and short-grain varieties. All varieties of rice can be processed post-harvest as either white or brown rice, affecting flavor, texture and nutritive value. Milling of rice post-harvest always leads to some grains being broken; a higher proportion of broken grains decreases the price since the quality is generally acknowledged to be reduced.
Rice provided 19% of global human per capita energy and 13% of per capita protein in 2009. Although rice protein ranks high in nutritional quality among cereals, protein content is modest. Environmental factors (soil fertility, wet or dry season, solar radiation, and temperature during grain development) and crop management (added nitrogen fertilizer, plant spacing) affect rice protein content. The nutritional content of rice also depends on the variety, how it is processed post-harvest, and how it is prepared for consumption.
Where rice is the main item of the diet, it is frequently the basic ingredient of every meal. Rice can be boiled or steamed, or else first ground into flour and made into noodles, breads, cakes, and other products. Besides the standard domestic cooking methods summarized here, rice can also be processed into other rice-based food and drink products. Some safety precautions apply when cooking and storing rice, and cooking/preparation methods are also associated with certain changes to nutritive value.
In addition to consuming rice grains cooked in the usual ways, there are many other rice-based food and drink products that can be prepared for human consumption.