More wheat flour is produced than any other flour. Wheat varieties are called "clean," "white," or "brown" if they have high gluten content, and they are called "soft" or "weak" flour if gluten content is low. Hard flour, or bread flour, is high in gluten, with 12% to 14% gluten content, and has elastic toughness that holds its shape well once baked. Soft flour is comparatively low in gluten and so results in a finer texture. [1] Soft flour is usually divided into cake flour, which is the lowest in gluten, and pastry flour, which has slightly more gluten than cake flour.
In terms of the parts of the grain (the grass fruit) used in flour—the endosperm or starchy part, the germ or protein part, and the bran or fibre part—there are three general types of flour. White flour is made from the endosperm only. Whole grain or wholemeal flour is made from the entire grain, including bran, endosperm, and germ. A germ flour is made from the endosperm and germ, excluding the bran.
- All-purpose or plain flour is a blended wheat flour with a gluten content lower than bread flour, ranging between 9% and 12%. Depending on brand or the region where it is purchased it may be composed of all hard or soft wheats or a blend of the two, and can range from low gluten content to moderately high. It is marketed as an inexpensive alternative to bakers' flours, supposedly acceptable for most household baking needs. [1]
- Bleached flour is treated with flour bleaching agents to whiten it (freshly milled flour is yellowish) and to 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.
- Bread Flour is always made from hard wheat, usually hard spring wheat. It has a very high gluten content, between 10% and 13%, making it excellent for yeast bread baking. [1]
- Bromated flour has a maturing agent added. The agent's role is to help with developing gluten, a role similar to the flour bleaching agents. Bromate is usually used. Other choices are phosphates, ascorbic acid, and malted barley. Bromated flour has been banned in much of the world, as bromate is classified as possibly carcinogenic in humans (Group 2B) by the International Agency for Research on Cancer (IARC).[2], but remains available in the United States.
- Cake flour is a finely milled flour made from soft wheat. It has very low gluten content, between 8% and 10%, making it suitable for soft-textured cakes and cookies. The higher gluten content of other flours would make the cakes tough. Highly sifted cake flours may require different volume amounts in recipes than all-purpose flour. Related to cake flour are masa harina (from maize), maida flour (from wheat or tapioca), and pure starches. [1]
- 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 USA and Europe.[citation needed] It is the basis of true graham crackers. Many graham crackers on the market are actually imitation grahams because they do not contain graham flour or even whole-wheat flour. Another difference, however, is that commercial graham crackers are designed to be flavorful, unlike Mr. Graham's vision of a bland diet aimed at curbing masturbation among other perceived social ills.
- Pastry flour or cookie flour or cracker flour has slightly higher gluten content than cake flour but lower than all-purpose flour. Its gluten content ranges between 9% and 10%. 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. [1]
- Self-rising or self-raising flour is flour that is sold premixed with chemical leavening agents. It was invented by Henry Jones. Self-rising flour is typically composed of the following ratio:
-
- 1 cup (100 g) flour
- 1 and 1/2 teaspoon (3 g) baking powder
- a pinch to ½ teaspoon (1 g or less) salt
- Sharp flour is produced in Fiji and primarily used in Indian cuisine.
- Spelt flour is a flour produced from the type of wheat called spelt. It is less commonly used in modern cooking than other wheat varieties. It is still used for speciality baking.
- Tang flour or wheat starch is a type of wheat flour used primarily in Chinese cooking for making the outer layer of dumplings and buns. It is also used in Vietnamese cuisine, where it is called bột lọc trong.
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