Their current geographical distribution is very broad; it ranges from China, India and Europe to South and North America (Leff et al. 2004). The following cereals will be briefly discussed: rice, wheat and oats.
The rice, a tall grass from the family Poaceae, is native to tropical and subtropical areas of South Asia since at least 500 B.C. (Munk 1972 and Thermo Sc. Inc. 2011) The grass produces a small oblong and starchy kernel protected by bran coats rich in minerals and vitamins. Nowadays, rice is grown all around the world were the climate has favorable conditions. China and India are the current producers of rice in the world, contributing with 90% of the world rice production (Leff et al. 2004 and Munk 1972). There are about 8 000 varieties of rice, and are classified according to their size, shape and color. .
The different methods used to clean, mill or polish rice, after being harvested, give the product its different nutritional properties (Munk 1972). Rice is a rich source of carbohydrates low in sodium, therefore provides energy. Brown rice in addition is richer in minerals and vitamins, especially thiamine. The world food organization decided to enrich rice with calcium, iron and many B-complex vitamins (Thermo Sc. Inc. 2011). People, in areas where rice is cultivated, use all parts of the plant to prepare beverages and in folk medicine. Unpolished rice is use a preventive and treatment for Beriberi (Munk 1972). .
The oats, an essential constituent of human diet, belong also to family Poaceae and arose in Europe. Oats are thought to come from two initial species, wild oats (A. fauta) and wild red oat (A. sterilis). In the modern day, the major producers of oat are USA, Southern Canada, Russia and the Mediterranean areas (Leff et al. 2004). Oat is the cereal with most variety of industrial uses, and new varieties of oat are produced each year (Friedman 1996). Oat is considered by far the most nutritious cereal with high content of vitamin B1, B2, E, polyunsaturated fatty acids, carbohydrates, sugars, fiber and amino acids.