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An ingredient used in many Food s, flour is a fine powder made from Cereal s or other Starch y food sources. It is most commonly made from Wheat , but also Maize (a.k.a. Corn ), Rye , Barley and Rice , amongst many other Grass es and non-grain plants (including many Australian species of Acacia ). Flour is the key ingredient of Bread , which is the staple food in many countries, and therefore the availability of adequate supplies of flour has often been a major economic and political issue. Flour can also be made from legumes and nuts, such as soy, peanuts, almonds, and other tree nuts. Flour is always based on the presence of Starch es, which are complex Carbohydrate s. Usually, the word "flour" used alone refers to wheat flour, which is one of the most important foods in European and American culture. Wheat flour is the main ingredient in most types of breads and pastries. Wheat is so widely used because of an important property: when wheat flour is mixed with water, a complex Protein called Gluten develops. The gluten development is what gives wheat dough an elastic structure that allows it to be worked in a variety of ways, and which allows the retention of gas bubbles in an intact structure, resulting in a sponge-like texture to the final product. This is highly desired for breads, cakes and other baked products. A coarser, somewhat granular preparation, rather than a fine dust, is often called meal. TYPES OF FLOUR Wheat flour The vast majority of today's flour consumption is Wheat flour. Wheat varieties are typically known as, variously, "white" or "brown" if they have high gluten content, and "soft" or "weak flour" if gluten content is low. Hard flour, or "bread" flour, is high in gluten and so forms a certain toughness that holds its shape well once baked. Soft flour is comparatively low in gluten and so results in a finer texture. 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. All-purpose flour is a blended wheat flour with an intermediate gluten level which is marketed as an acceptable compromise for most household baking needs. In terms of the parts of the grain (the grass Seed ) used in flour -- the endosperm or starchy part, the germ or protein part, and the bran or fiber part -- there are three general types of flour. White flour is made from the endosperm only. '''Whole grain''' 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. Whole-wheat Flour is whole-grain wheat flour. Bleached flour is flour that was subjected to Flour Bleaching Agent s in order to whiten it (freshly milled flour is yellowish) and give it more Gluten -producing potential. Similar effect can be achieved by letting the flour slowly oxidize with oxygen in the air ("natural aging"); however this process is too slow to be commercially viable. Oxidizing agents are therefore employed, most commonly Organic Peroxide s like Acetone Peroxide or Benzoyl Peroxide , Nitrogen Dioxide , or Chlorine . Bromated flour is flour with a Maturing Agent added. The agent's role is to help with developing Gluten , a role similar to the Flour Bleaching Agent s. Bromate is usually used. Other choices are Phosphate s, Ascorbic Acid , and Malted Barley . Cake flour is a finely milled flour made from soft wheat. It has very low gluten content, making it suitable for soft-textured Cake s and Cookie s. Higher gluten content of other flours would make the cakes tough. 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 . It is the basis of true Graham Cracker s. Many graham crackers on the market are actually imitation grahams because they do not contain graham flour or even whole-wheat flour. Pastry flour (also called '''cookie flour''' or '''cracker flour''') has slightly higher gluten content than cake flour, but lower than all-purpose flour. It is suitable for fine, light-textured Pastries . Self-rising or '''self-raising flour''' is "white" wheat flour that is sold premixed with chemical leavening agents. It was invented by Henry Jones . Typical ratios are: :U.S. customary: ::one cup flour ::1 to 1 1/2 teaspoon Baking Powder ::a pinch to 1/2 teaspoon salt :Metric: ::100 g flour ::3 g baking powder ::1 g or less salt Durum flour is made of durum wheat. It has the highest protein content, and it is an important component of nearly all Noodle s and Pasta s. Other flours
Flour can also be made from Buckwheat , Soy beans, Arrowroot , Potato es, Taro , Cattail s, Acorn s and other non-grain foodstuffs. FLOUR TYPE NUMBERS In some markets, the different available flour varieties are labeled according to the ash mass ("mineral content") that remains after a sample was incinerated in a laboratory oven (typically at 550 °C or 900 °C, see International Standard s ISO 2171 and ICC 104/1 ). This is an easy to verify indicator for the fraction of the whole grain that ended up in the flour, because the mineral content of the starchy endosperm is much lower than that of the outer parts of the grain. Flour made from all parts of the grain (extraction rate: 100%) leaves about 2 g ash or more per 100 g dry flour. Plain white flour (extraction rate: 50-60%) leaves only about 0.4 g.
In the United States and the United Kingdom, no numbered standardized flour types are defined, and the ash mass is only rarely given on the label by flour manufacturers. However, the legally required standard nutrition label specifies the protein content of the flour, which is also a suitable way for comparing the extraction rates of different available flour types. In general, as the extraction rate of the flour increases, so do both the protein and the ash content. However, as the extraction rate approaches 100% (whole meal), the protein content drops slightly, while the ash content continues to rise. The following table shows some typical examples of how protein and ash content relate to each other in wheat flour: This table is only a rough guideline for converting bread recipes. Since the American flour types are not standardized, the numbers may differ between manufacturers. FLOUR PRODUCTION Milling of flour is accomplished by grinding grain between Stones or steel wheels. Today, "stone-ground" usually means that the grain has been ground in a Water-operated Mill , in which a revolving stone wheel turns over a stationary stone wheel, with the grain in between. Many small appliance mills are now available, both hand-cranked and electric. Flour dust suspended in air is explosive, as is any mixture of a finely powdered flammable substance with air ''see'' Lycopodium . Some of the worst civilian fatalities from explosions have been at flour mills. HISTORY In history, both large and hand mills were operated. Until modern times, much flour contained minute amounts of grit, either the result of poor sifting of the grain or of grinding stones together. This grit strongly abraded teeth. One of the most ancient methods of grinding to produce flour was by using a pair of Quern-stone s. These were made out of rock, and were ground together by hand. They were generally replaced by Millstone s once mechanised forms of Milling appeared, particularly the Water Mill and the Windmill , although animals were also used to operate the millstones. FLOUR PRODUCTS Bread , Pasta , Cracker s, many Cake s, amongst many other foods, are made using flour. Wheat flour is also used to make a Roux as a base for Gravy and Sauce s. White wheat flour is the traditional base for Wallpaper paste. It is also the base for Papier-mâché . Cornstarch is a principal ingredient of many Pudding s. EXTERNAL LINKS
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