Grains are a group of foods that includes maize, oats, barley, wheat, rye, sorghum and others. As widely reported, grain products are divided into two categories: refined and whole grain. The earlier is achieved by food manufacturers through milling, whereby the germ, bran and the endosperm are removed. The latter is just the whole grain itself. Grain milling is the milling of flour and rice; the malting of grain (primarily barley); and the mixing of prepared flour mixes and dough. Maize, rice and wheat constituted 87 percent of all grain production worldwide and 43 percent of food calories in 2003.