flour

1. A fine, powdery foodstuff obtained by grinding and sifting the meal of a grain, especially wheat, used chiefly in baking.
2. Any of various similar finely ground or powdered foodstuffs, as of cassava, fish, or bananas.
3. A soft, fine powder.

1. To cover or coat with flour.
2. To make into flour.

[Middle English, flower, best of anything, flour. See flower.]

Background

Flour is a finely ground powder prepared from grain or other starchy plant foods and used in baking. Although flour can be made from a wide variety of plants, the vast majority is made from wheat. Dough made from wheat flour is particularly well suited to baking bread because it contains a large amount of gluten, a substance composed of strong, elastic proteins. The gluten forms a network throughout the dough, trapping the gases which are formed by yeast, baking powder, or other leavening agents. This causes the dough to rise, resulting in light, soft bread.

Flour has been made since prehistoric times. The earliest methods used for producing flour all involved grinding grain between stones. These methods included the mortar and pestle (a stone club striking grain held in a stone bowl), the saddlestone (a cylindrical stone rolling against grain held in a stone bowl), and the quern (a horizontal, disk-shaped stone spinning on top of grain held on another horizontal stone). These devices were all operated by hand.

The millstone, a later development, consisted of one vertical, disk-shaped stone rolling on grain sitting on a horizontal, disk-shaped stone. Millstones were first operated by human or animal power. The ancient Romans used waterwheels to power millstones. Windmills were also used to power millstones in Europe by the twelfth century.

The first mill in the North American colonies appeared in Boston in 1632 and was powered by wind. Most later mills in the region used water. The availability of water power and water transportation made Philadelphia, Pennsylvania, the center of milling in the newly independent United States. The first fully automatic mill was built near Philadelphia by Oliver Evans in 1784. During the next century, the center of milling moved as railroads developed, eventually settling in Minneapolis, Minnesota. During the nineteenth century numerous improvements were made in mill technology. In 1865, Edmund La Croix introduced the first middlings purifier in Hastings, Minnesota. This device consisted of a vibrating screen through which air was blown to remove bran from ground wheat. The resulting product, known as middlings or farina, could be further ground into high-quality flour. In 1878, the first important roller mill was used in Minneapolis, Minnesota. This new type of mill used metal rollers, rather than millstones, to grind wheat. Roller mills were less expensive, more efficient, more uniform, and cleaner than millstones. Modern versions of middlings purifiers and roller mills are still used to make flour today.

Raw Materials

Although most flour is made from wheat, it can also be made from other starchy plant foods. These include barley, buckwheat, corn, lima beans, oats, peanuts, potatoes, soybeans, rice, and rye. Many varieties of wheat exist for use in making flour. In general, wheat is either hard (containing 11-18% protein) or soft (containing 8-11% protein). Flour intended to be used to bake bread is made from hard wheat. The high percentage of protein in hard wheat means the dough will have more gluten, allowing it to rise more than soft wheat flour. Flour intended to be used to bake cakes and pastry is made from soft wheat. All-purpose flour is made from a blend of soft and hard wheat. Durum wheat is a special variety of hard wheat, which is used to make a kind of flour called semolina. Semolina is most often used to make pasta.

Flour usually contains a small amount of additives. Bleaching agents such as benzoyl peroxide are added to make the flour more white. Oxidizing agents (also known as improvers) such as potassium bromate, chlorine dioxide, and azodicarbonamide are added to enhance the baking quality of the flour. These agents are added in a few parts per million. Self-rising flour contains salt and a leavening agent such as calcium phosphate. It is used to make baked goods without the need to add yeast or baking powder. Most states require flour to contain added vitamins and minerals to replace those lost during milling. The most important of these are iron and the B vitamins, especially thiamin, riboflavin, and niacin.

The Manufacturing
Process

Grading the wheat

• Wheat is received at the flour mill and inspected. Samples of wheat are taken for physical and chemical analysis. The wheat is graded based on several factors, the most important of which is the protein content. The wheat is stored in silos with wheat of the same grade until needed for milling.

Purifying the wheat

• Before wheat can be ground into flour it must be free of foreign matter. This requires several different cleaning processes. At each step of purification the wheat is inspected and purified again if necessary.
• The first device used to purify wheat is known as a separator. This machine passes the wheat over a series of metal screens. The wheat and other small particles pass through the screen while large objects such as sticks and rocks are removed.
• The wheat next passes through an aspirator. This device works like a vacuum cleaner. The aspirator sucks up foreign matter which is lighter than the wheat and removes it.

• 5 Other foreign objects are removed in various ways. One device, known as a disk separator, moves the wheat over a series of disks with indentations that collect objects the size of a grain of wheat. Smaller or larger objects pass over the disks and are removed.

• Another device, known as a spiral seed separator, makes use of the fact that wheat grains are oval while most other plant seeds are round. The wheat moves down a rapidly spinning cylinder. The oval wheat grains tend to move toward the center of the cylinder while the round seeds tend to move to the sides of the cylinder, where they are removed.
• Other methods used to purify wheat include magnets to remove small pieces of metal, scourers to scrape off dirt and hair, and electronic color sorting machines to remove material which is not the same color as wheat.

Preparing the wheat for grinding

• The purified wheat is washed in warm water and placed in a centrifuge to be spun dry. During this process any remaining foreign matter is washed away.
• The moisture content of the wheat must now be controlled to allow the outer layer of bran to be removed efficiently during grinding. This process is known as conditioning or tempering. Several methods exist of controlling the amount of water present within each grain of wheat. Usually this involves adding, rather than removing, moisture.
• Cold conditioning involves soaking the wheat in cold water for one to three days. Warm conditioning involves soaking the wheat in water at a temperature of 115°F (46°C) for 60-90 minutes and letting it rest for one day. Hot conditioning involves soaking the wheat in water at a temperature of 140°F (60°C) for a short period of time. This method is difficult to control and is rarely used. Instead of water, wheat may also be conditioned with steam at various temperatures and pressures for various amounts of time. If conditioning results in too much moisture, or if the wheat happens to be too moist after purification, water can be removed by vacuum dryers.

Grinding the wheat

• Wheat of different grades and moistures is blended together to obtain a batch of wheat with the characteristics necessary to make the kind of flour being manufactured. At this point, the wheat may be processed in an Entoleter, a trade name for a device with rapidly spinning disks which hurl the grains of wheat against small metal pins. Those grains which crack are considered to be unsuitable for grinding and are removed.
• The wheat moves between two large metal rollers known as breaker rolls. These rollers are of two different sizes and move at different speeds. They also contain spiral grooves which crack open the grains of wheat and begin to separate the interior of the wheat from the outer layer of bran. The product of the breaker rolls passes through metal sieves to separate it into three categories. The finest material resembles a coarse flour and is known as middlings or farina. Larger pieces of the interior are known as semolina. The third category consists of pieces of the interior which are still attached to the bran. The middlings move to the middlings purifier and the other materials move to another pair of breaker rolls. About four or five pairs of breaker rolls are needed to produce the necessary amount of middlings.
• The middlings purifier moves the middlings over a vibrating screen. Air is blown up through the screen to remove the lighter pieces of bran which are mixed with the middlings. The middlings pass through the screen to be more finely ground.
• Middlings are ground into flour by pairs of large, smooth metal rollers. Each time the flour is ground it passes through sieves to separate it into flours of different fineness. These sieves are made of metal wire when the flour is coarse, but are made of nylon or silk when the flour is fine. By sifting, separating, and regrinding the flour, several different grades of flour are produced at the same time. These are combined as needed to produce the desired final products.

Processing the flour

• Small amounts of bleaching agents and oxidizing agents are usually added to the flour after milling. Vitamins and minerals are added as required by law to produce enriched flour. Leavening agents and salt are added to produce self-rising flour. The flour is matured for one or two months.
• The flour is packed into cloth bags which hold 2, 5, 10, 25, 50, or 100 lb (About 0.9, 2.3, 4.5, 11.3, 22.7, or 45.4 kg). For large-scale consumers, it may be packed in metal tote bins which hold 3000 lb (1361 kg), truck bins which hold 45,000 lb (20,412 kg), or railroad bins which hold 100,000 lb (45,360 kg).

Quality Control

The quality control of flour begins when the wheat is received at the flour mill. The wheat is tested for its protein content and for its ash content. The ash content is the portion which remains after burning and consists of various minerals.

During each step of the purification process, several samples are taken to ensure that no foreign matter ends up in the flour. Since flour is intended for human consumption, all the equipment used in milling is thoroughly cleaned and sterilized by hot steam and ultraviolet light. The equipment is also treated with antibacterial agents and antifungal agents to kill any microscopic organisms which might contaminate it. Hot water is used to remove any remaining traces of these agents.

The final product of milling is tested for baking in test kitchens to ensure that it is suitable for the uses for which it is intended. The vitamin and mineral content is measured in order to comply with government standards. The exact amount of additives present is measured to ensure accurate labeling.

Byproducts/Waste

A kernel of wheat consists of three parts, two of which can be considered byproducts of the milling process. The bran is the outer covering of the kernel and is high in fiber. The germ is the innermost portion of the kernel and is high in fat. The endosperm makes up the bulk of the kernel and is high in proteins and carbohydrates. Whole wheat flour uses all parts of the kernel, but white flour uses only the endosperm.

Bran removed during milling is often added to breakfast cereals and baked goods as a source of fiber. It is also widely used in animal feeds. Wheat germ removed during milling is often used as a food supplement or as a source of edible vegetable oil. Like bran, it is also used in animal feeds.

Where to Learn More

Books

Besant, Lloyd. Grains: Production, Processing, Marketing. Chicago Board of Trade, 1982.

Kent, N. L. Technology of Cereals: With Special Reference to Wheat. Pergamon Press, 1975.

Periodicals

Sokolov, Raymond. "Through a Mill, Coarsely." Natural History, February 1994, pp. 72-74.

Wrigley, Colin W. "Giant Proteins With Flour Power." Nature, June 27, 1996, pp. 738-739.

Other

"How Flour is Made." The Story of Wheat. University of Saskatchewan College of Agricultural Sciences. December 7, 1996. http://pine.usask.ca/cofa/displays/college/story/wheat.html.

[Article by: Rose Secrest]

Most commonly refers to ground wheat, although also used for other cereals and applied to powdered dried matter such as fish flour, potato flour, etc. Ground wheat yields wholemeal flour (100% extraction); whiter flours are obtained by separation of the bran and the germ from the starchy endosperm. See also bread; flour, extraction rate.

n. The finely ground and sifted meal of any of various edible grains. Giant steel or stone rollers are used to break and grind the grain. Most supermarkets carry steel-ground flour, meaning it's crushed with huge, high-speed steel rollers or hammers. The heat that is generated with these high-velocity machines strips away the wheat germ and destroys valuable vitamins and enzymes. The more naturally nutritious stone-ground flour is produced by grinding the grain between two slowly moving stones. This process crushes the grain without generating excess heat and separating the germ. Stone-ground flours must usually be purchased in natural food stores, though some large supermarkets also carry them. A flour can range in texture from coarse to extremely soft and powdery, depending on the degree of bolting (sifting) it receives at the mill. Wheat is the most common source of the multitude of flours used in cooking. It contains gluten, a protein that forms an elastic network that helps contain the gases that make mixtures (such as doughs and batters) rise as they bake. All-purpose flour is made from a blend of high-gluten hard wheat and low-gluten soft wheat. It's a fine-textured flour milled from the inner part of the wheat kernel and contains neither the germ (the sprouting part) nor the bran (the outer coating). U.S. Law requires that all flours not containing wheat germ must have niacin, riboflavin, thiamin and iron added. (Individual millers sometimes also add vitamins A and D.) These flours are labeled "enriched." All-purpose flour comes in two basic forms-bleached and unbleached-that can be used interchangeably. Flour can be bleached either naturally, as it ages, or chemically. Most flour on the market today is presifted, requiring only that it be stirred, then spooned into a measuring cup and leveled off. Bread flour is an unbleached, specially formulated, high-gluten blend of 99.8 percent hard-wheat flour, a small amount of malted barley flour (to improve yeast activity) and vitamin C or potassium bromate (to increase the gluten's elasticity and the dough's gas retention). It is ideally suited for yeast breads. The fuller-flavored whole-wheat flour contains the wheat germ, which means that it also has a higher fiber, nutritional and fat content. Because of the latter, it should be stored in the refrigerator to prevent rancidity. Cake or pastry flour is a fine-textured, soft-wheat flour with a high starch content. It makes particularly tender cakes and pastries. Self-rising flour is an all-purpose flour to which baking powder and salt have been added. It can be substituted for all-purpose flour in yeast breads by omitting the salt and in quick breads by omitting both baking powder and salt. Instant flour is a granular flour especially formulated to dissolve quickly in hot or cold liquids. It's used mainly as a thickener in sauces, gravies and other cooked mixtures. Gluten flour is high-protein, hard-wheat flour treated to remove most of the starch (which leaves a high gluten content). It's used mainly as an additive to doughs made with low-gluten flour (such as rye flour), and to make low-calorie "gluten" breads. All flour should be stored in an airtight container. All-purpose and bread flour can be stored up to 6 months at room temperature (about 70°F). Temperatures higher than that invite bugs and mold. Flours containing part of the grain's germ (such as whole wheat) turn rancid quickly because of the oil in the germ. Refrigerate or freeze these flours tightly wrapped and use as soon as possible. Other grains-such as barley, buckwheat, corn, oats, rice rye and triticale-are also milled into flours. flour v. To lightly coat a food, utensil or baking container with flour. Flouring food to be fried facilitates browning, and coating foods that tend to stick together (such as chopped dried apricots) helps separate the pieces. Flouring a pie, pastry or cookie dough will prevent it from sticking to a work surface; flouring your hands, rolling pin or work surface prevents dough from sticking. Dusting greased baking pans with flour provides for easy removal of cakes, breads and other baked goods.

For more information on flour, visit Britannica.com.

Tutor's tip: The baker wore a "flower" (the colorful part of a plant) in her hair as she mixed "flour" (a fine substance, usually food, produced by grinding grain) with sugar.

Dansk (Danish)
n. - mel, hvedemel, stenmel
v. tr. - drysse med mel, mele, formale og sigte

Nederlands (Dutch)
bloem, bakmeel, met bloem bedekken, verpoederen

Français (French)
n. - farine, substance poudreuse
v. tr. - saupoudrer de farine

Deutsch (German)
n. - Mehl
v. - mahlen, mit Mehl bestreuen

Ελληνική (Greek)
n. - αλεύρι
v. - (μαγειρ.) αλευρώνω

Italiano (Italian)
farina

Português (Portuguese)
n. - farinha (f) de trigo
v. - polvilhar farinha

Русский (Russian)
мука, порошок, обваливать в муке

Español (Spanish)
n. - harina
v. tr. - enharinar

Svenska (Swedish)
n. - vetemjöl
v. - beströ med mjöl, finmala

中文（简体）(Chinese (Simplified))
面粉, 碎粉, 粉沫, 撒粉于, 把...磨成粉

中文（繁體）(Chinese (Traditional))
n. - 麵粉, 碎粉, 粉沫
v. tr. - 撒粉於, 把...磨成粉

한국어 (Korean)
n. - 밀가루 소맥분, 고운 가루
v. tr. - ~을 가루로 빻다

日本語 (Japanese)
n. - 穀粉, 小麦粉, 粉末
v. - 粉を振りかける, 粉にする, 粉末になる, 風化して粉になる

العربيه (Arabic)
‏(الاسم) طحين (فعل) يكسو بالطحين‏

עברית (Hebrew)
n. - ‮קמח‬
v. tr. - ‮קימח, בזק קמח‬

If you are unable to view some languages clearly, click here.

To select your translation preferences click here.