flour, finely ground, usually sifted, meal of grain, such as wheat, rye, corn, rice, or buckwheat. Flour is also made from potatoes, peas, beans, peanuts, etc. Usually it refers to the finely ground and bolted (i.e., sifted through a fine sieve) flour of wheat, which forms the largest proportion of all flour milled in the United States, Canada, and W Europe. Millet is ground in India, Russia, and China. Rye is much used for bread in N Europe, buckwheat in the Netherlands and Russia, and corn in the United States. Rice may be used for bread in combination with other grains richer in gluten. Wheat and rye flour can be used in baking leavened bread, as they contain gluten in sufficient amount to retain the gas formed by the action of yeast. Corn flour, rich in fats and starches, is a favorite for making quick breads. Graham, or whole-wheat, flour contains the whole grain, unbolted. This flour will not keep long, as the germ contains fats and ferments that cause deterioration when exposed to the air. Wheat flour is separated into grades by milling. In the United States, patent flour, freed of the bran and most of the germ, is the highest grade; clear flour is the second grade; and red dog, a low-grade residue, is used mainly for animal feed. The composition of flour depends on the type of wheat and the milling processes; gluten is the chief protein, and starch the principal carbohydrate, although some sucrose, invert sugar, and dextrin may be present. On the market are prepared flours, such as the self-rising, which contains a leavening agent, and numerous cake, pancake, and pastry mixes requiring only the addition of water. Flour improves if stored from six to nine months under conditions permitting the enzyme action that gives better baking qualities. Good flour, rich in gluten, has a creamy color and adhesive quality. Bleaching, which is accomplished by the addition of chemicals to flour to improve its appearance and baking qualities, was begun about 1900. The bleaching of flour has been a controversial issue since its beginning, with charges that it destroys valuable nutrients or is injurious to health; some bleaching agents have been banned (e.g., nitrogen trichloride), but new ones have been introduced. Bleached flours must be so labeled.