is always made from hard wheat, usually hard spring wheat. It has a very high protein content, between 10% and 13%, making it excellent for yeast bread baking. It can be white or whole wheat or in between. Cake flour is a finely milled white flour made from soft wheat. It has very low protein content, between 8% and 10%, making it suitable for soft-textured cakes and cookies. The higher protein content of other flours would make the cakes tough. Related to cake flour are masa harina (from maize), maida flour (from wheat or tapioca), and pure starches. Durum flour is made from Durum wheat and is suited for pasta making, traditional pizza and flatbread for doner kebab. Graham flour is a special type of whole wheat flour. The endosperm is finely ground, as in white flour, while the bran and germ are coarsely ground. Graham flour is uncommon outside of the United States (but see atta flour, a similar product, below). Graham flour is the basis of true graham crackers. Instant flour is pregelatinized (precooked) for easier incorporation in gravies and sauces. Pastry flour or cookie flour or cracker flour has slightly higher protein content than cake flour but lower than all-purpose flour. Its protein content ranges between 9% and 10%. It is available as a white flour, a whole-wheat flour, or a white flour with the germ retained but not the bran. It is suitable for pie pastry and tarts, some cookies, muffins, biscuits and other quick breads. Flour is shaken through a sieve to reduce the amount of lumps for cooking pastry. Whole-wheat flour contains the wheat germ, endosperm and bran White flour or refined flour contains only the endosperm Whole-wheat white flour is white flour that contains the endososperm, bran, and germ Enriched flour is white flour with nutrients added to compensate for the removal of the bran and germ Bleached flour is a white flour treated with flour bleaching agents to whiten it (freshly milled flour is yellowish) and give it more gluten-producing potential. Oxidizing agents are usually employed, most commonly organic peroxides like acetone peroxide or benzoyl peroxide, nitrogen dioxide, or chlorine. A similar effect can be achieved by letting the flour oxidize with oxygen in the air ("natural aging") for approximately 10 days; however, this process is more expensive due to the time required. Flour bleached with benzoyl peroxide has been prohibited in