Cereals are a set of herbaceous plants whose grains or seeds are used for human nourishment or that of cattle, generally ground in the shape of flour. The word cereal comes from Ceres, the name in Latin of the goddess of Agriculture. Cereals contain the starch wich is the principal component of the human food. The germ of the seed contains lípidos in changeable proportion that allows the extraction of vegetable oil of certain cereals. The seed is inside a rind formed especially by the cellulose, fundamental component of dietetic fiber. Some cereals contain a protein "the gluten" wich is indispensable to the formation of bread. The proteins of the cereals are scanty in essential amino acids as the lisina.