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For other uses, see Flour (disambiguation).
Look up flour in Wiktionary, the free dictionary.
wheat flour
An ingredient flour is a fine powder made by grinding cereal grains or other suitable edible plant matter that is high in starch. It is most commonly made from wheat — the word "flour" used without qualification implies wheat flour — but also maize (now called corn in many parts of the Western Hemisphere), rye, barley, and rice, amongst many other grasses and non-grain plants (including buckwheat, grain amaranths and many Australian species of acacia). Ground legumes and nuts, such as soy, peanuts, almonds, and other tree nuts, are also called flours. Finally flours can be made by grinding the roots of several plants, including cassava, arrowroot and taro. The same substances ground more coarsely are, many cases, called "meal" instead of "flour".
Flour is the key ingredient of bread, which is a staple food in many countries, and therefore the availability of adequate supplies of flour has often been a major economic and political issue. Wheat flour is one of the most important foods in European and North American culture, and is the defining ingredient in most European styles of breads and pastries. Regulations in many countries require that wheat flour be enriched to replace nutrients lost in the production of refined flour.
Flour, by definition, contains a high proportion of starches, which are complex carbohydrates also known as polysaccharides. Wheat, and some other, flours also contain proteins called gluten. When dough made with wheat flour is kneaded, the gluten molecules cross-link to form a sub-microscopic network that gives the dough an elastic structure. This allows the retention of gas bubbles in an intact structure, resulting in an aerated final product with a soft texture, desirable for breads, cakes and the like. Some people suffer from an intolerance to gluten known as coeliac or celiac disease. Increased awareness of this disorder, as well as a rising belief in the benefits of a gluten-free diet for persons suffering certain other conditions, has led to an increased demand for bread, pasta, and other products made with flours that do not contain gluten.
Contents |
| Protein | |
|---|---|
| 5-8% | cake flour |
| 8-10% | pastry flour |
| 10-11.5% | all-purpose flour |
| 11-13% | bread flour |
| 14% and up | high-gluten flour |
Much more wheat flour is produced than any other flour.
Wheat varieties are called "clean", "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, with 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.
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.
In Britain, many flours go by names different than those from America. Some American flours and British equivalents include:
Flour can also be made from soy beans, peanuts, arrowroot, taro, cattails, acorns and other non-cereal foodstuffs.
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 standards 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.
It is possible to find out ash content from some US manufacturers. However, US measurements are based on wheat with a 14% moisture content. Thus, a US flour with .48 ash would approximate a French Type 55.
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:
| Ash | Protein | Wheat flour type | ||
|---|---|---|---|---|
| US | German | French | ||
| ~0.4% | ~9% | pastry flour | 405 | 45 |
| ~0.55% | ~11% | all-purpose flour | 550 | 55 |
| ~0.8% | ~14% | high gluten flour | 812 | 80 |
| ~1% | ~15% | first clear flour | 1050 | 110 |
| >1.5% | ~13% | white whole wheat | 1600 | 150 |
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.
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 mill in which a revolving stone wheel turns over a stationary stone wheel, vertically or horizontially with the grain in between. Many small appliance mills are 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,Williamson, George (06-02-2002). Introduction to Dust Explosions. Retrieved on 2006-10-29. see Lycopodium. The most benign cases occur in classroom flour bombs. In medieval flour mills, candles, lamps, or other sources of fire were forbidden. Some devastating and fatal explosions have occurred at flour mills, including an explosion in 1878 at the Washburn "A" Mill in Minneapolis, the largest flour mill in the United States at the time.Washburn ‘A’ Mill Explosion. Minnesota Historical Society Library History Topics. Retrieved on 2006-10-29.
Bread, pasta, crackers, many cakes, and many other foods are made using flour. Wheat flour is also used to make a roux as a base for gravy and sauces. 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 puddings or desserts.
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