Flour is a powder made of cereal grains or roots. It is the main ingredient of bread, which is a staple food for many civilizations, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history. 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. Maize flour has been important in Mesoamerican cuisine since ancient times, and remains a staple in much of Latin American cuisine.

Flour contains high proportion of starches, which are complex carbohydrates also known as polysaccharides. Leavening agents are used with some flours, especially those with significant gluten content, to produce lighter and softer baked products by embedding small gas bubbles.

The production of flour has also historically driven technological development, as attempts to make gristmills more productive and less labor-intensive led to the watermill and windmill, terms now applied more broadly to uses of water and wind power for purposes other than milling.

Etymology

The word "flour" was originally a variant of the word "flower." Both derive from the Old French fleur or flour, which had the literal meaning "blossom," and a figurative meaning "the finest." The phrase "fleur de farine'" meant "the finest part of the meal," since flour resulted from the elimination of coarse and unwanted matter from the grain during milling.

Degerminated and heat processed flour

A central problem of the industrial revolution was the preservation of flour. Transportation distances and a relatively slow distribution system collided with natural shelf life. The reason for the limited shelf life is the fatty acids of the germ which react from the moment they are exposed to oxygen. This occurs when grain is milled; the fatty acids oxidize and flour starts to become rancid.Depending on climate and grain quality this process takes 6 to 9 months. In the late 19th century this period was too short for an industrial production and distribution cycle. As vitamins, micronutrients and amino acids were completely or relatively unknown in the late 19th century, taking out the germ was a brilliant solution. Without the germ, flour cannot become rancid. Degerminated flour became standard.Degermination started in densely populated areas and took approximately one generation to reach the countryside.Heat-processed flour is flour where the germ is first separated from the endosperm and bran, then processed with steam, dry heat or microwave and submerged into flour again.

Types

Wheat flour

Other flours

• Amaranth flour is a flour produced from ground Amaranth grain. It was commonly used in pre-Columbian meso-American cuisine. It is becoming more and more available in speciality food shops.
• Atta flour is a whole-grain wheat flour important in Indian and Pakistani cuisine, used for a range of breads such as roti, naan and chapati.
• Bean flour is a flour produced from pulverized dried or ripe beans.
• Brown rice flour is of great importance in Southeast Asian cuisine. Also edible rice paper can be made from it. Most rice flour is made from white rice, thus is essentially a pure starch, but whole-grain brown rice flour is commercially available.
• Buckwheat flour is used as an ingredient in many pancakes in the United States. In Japan, it is used to make a popular noodle called Soba. In Russia, buckwheat flour is added to the batter for pancakes called blinis which are frequently eaten with caviar. Buckwheat flour is also used to make crêpes bretonnes in Brittany. On Hindu fasting days (Navaratri mainly, also Maha Shivaratri), people eat items made of buckwheat flour. The preparation varies across India. The famous ones are Kuttu Ki Puri and Kuttu Pakoras. In most of northern and western states they call this Kuttu ka atta.
• Chestnut flour is popular in Corsica, the Périgord and Lunigiana for breads, cakes and pastas. It is the original ingredient for "polenta", still used as such in Corsica and other Mediterranean locations. Chestnut bread keeps fresh for as long as two weeks. In other parts of Italy it is mainly used for desserts.
• Chickpea flour (also known as gram flour or besan) is of great importance in Indian cuisine, and in Italy, where it is used for the Ligurian farinata.
• Chuño flour made from dried potatoes in various countries of South America
• Corn (maize) flour is popular in the Southern and Southwestern US, Mexico, South America, and Punjab regions of India (In India it called as Besan) and Pakistan. Coarse whole-grain corn flour is usually called corn meal. Corn meal that has been bleached with lye is called masa harina (see masa) and is used to make tortillas and tamales in Mexican cooking. Corn flour should never be confused with cornstarch, which is known as "cornflour" in British English. In India and Pakistan it is mixed with Spice and the paste is deep fried to make 'Pakoroas'.
• Cornstarch is just the "refined form" of Cornflour.
• Glutinous rice flour or sticky rice flour, used in east and southeast Asian cuisines for making tangyuan etc.
• Noodle flour is special blend of flour used for the making of Asian style noodles. The flour could be from wheat or rice.
• Nut flours are grated from oily nuts—most commonly almonds and hazelnuts—and are used instead of or in addition to wheat flour to produce more dry and flavourful pastries and cakes. Cakes made with nut flours are usually called tortes and most originated in Central Europe, in countries such as Hungary and Austria.
• Peasemeal or pea flour is a flour produced from roasted and pulverized yellow field peas.
• Peanut Flour made from shelled/cooked peanuts is a higher protein alternative to using regular flour
• Potato starch flour is obtained by grinding the tubers to a pulp and removing the fibre by water-washings. The dried product consists chiefly of starch, but also contains some protein. Potato starch flour is used as a thickening agent. When heated to boiling, food added with a suspension of potato flour in water thickens quickly. Because the flour is made from neither grain nor legume, it is used as substitute for wheat flour in cooking by Jews during Passover, when grains are not eaten. Often confused with Potato flour a peeled, cooked potato dried and grinded potato flakes. Potato flour is cold water soluble, dehydraded potato.
• Rice flour is ground kernels of rice. It is used in Western countries and especially for people who suffer from gluten intolerance, since rice does not contain gluten.
• Rye flour is used to bake the traditional sourdough breads of Poland, Germany and Scandinavia. Most rye breads use a mix of rye and wheat flours because rye does not produce a sufficient amount of gluten. Pumpernickel bread is usually made exclusively of rye, and contains a mixture of rye flour and rye meal.
• Tapioca flour, produced from the root of the cassava plant, is used to make breads, pancakes, tapioca pudding, a savoury porridge called fufu in Africa, and is used as a starch.
• Teff flour is made from the grain teff, and is of considerable importance in eastern Africa (particularly around the horn of Africa). Notably, it is the chief ingredient in the bread injera, an important component of Ethiopian cuisine.

Flour can also be made from soy beans, peanuts, arrowroot, taro, cattail, acorns, quinoa and other non-cereal foodstuffs. In Australia, a variety of other seeds are also used to make flour for bread, these include: Acacia aneura (mulga), Acacia cowleana, Acacia estrophiolata (ironweed), Acacia ligulata (umbrella bush), Acacia murrayana (tjuntjula), Acacia tetragonophylla (wakalpulka), Acacia kempeana (Witchetty bush), Acacia coriacea (Wiry wattle), Panicum spp. (eg Panicum australiense, Panicum decompositum, Panicum effusum), Astrelba pectinata (Mitchell grass), Portulaca oleracea, Portulaca intraterranea, Oryza sativa, Marsilea drummondii (Nardoo), Atriplex nummularia (Old man saltbush), Acacia notabilis, Acacia pyrifolia, Acacia tetragonophylla, Acacia victoriae, Acacia sophorae, Acacia stenophylla, Acacia tumida, Aleurites moluccana, Amaranthus mitchellii, Amaranthus grandiflorus, Brachiaria piligera, Brachiaria milliformis, Brachychiton diversifolium, Brachychiton gregorii, Brachychiton paradoxum, Brachychiton populneum, Bruguiera rheedii, Calandrinia balonensis, Canarium australianum, Canavalia maritima, Entada phaseolides, Eragrostris eriopoda (Wangunu), Eucalyptus leptopoda, Eucalyptus microtheca, Nymphae gigantea, Rhyncharrhena linearis, Themeda australis

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 standards ISO 2171 and ICC 104/1). This is an easily verified 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.

• German flour type numbers (Mehltype) indicate the amount of ash (measured in milligrams) obtained from 100 g of the dry mass of this flour. Standard wheat flours (defined in DIN 10355) range from type 405 for normal white wheat flour for baking, to strong bread flour types 550, 650, 812, and the darker types 1050 and 1600 for wholegrain breads.
• French flour type numbers (type de farine) are a factor 10 smaller than those used in Germany, because they indicate the ash content (in milligrams) per 10 g flour. Type 55 is the standard, hard-wheat white flour for baking, including puff pastries ("pâte feuilletée"). Type 45 is often called pastry flour, but is generally from a softer wheat. Types 65, 80, and 110 are strong bread flours of increasing darkness, and type 150 is a wholemeal flour.

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. For US bakers of French pastry seeking an equivalent, for example, they could look at tables published by King Arthur Flour, showing their all-purpose flour is a close equivalent to 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	40
~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 flour types are not standardized in many countries, the numbers may differ between manufacturers.

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 mill in which a revolving stone wheel turns over a stationary stone wheel, vertically or horizontally with the grain in between. Many small appliance mills are available, both hand-cranked and electric. The mill stones frequently rub against each other resulting in small stone particles chipping off and getting into flour. The safety aspect of this has not been checked but research into the dentition of medieval skeletons indicates that this form of milling leads to excessive wear on teeth. Steel roller mills do not have this problem.

Flammability

Flour dust suspended in air is explosive, as is any mixture of a finely powdered flammable substance with air, see Flour Bomb. 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.

Products

Bread, pasta, cracker, 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.

References

1. Goldkeim - Association to promote vital flour http://www.goldkeim.com/
2. The Grocer's Encyclopedia - Encyclopedia of Foods and Beverages. By Artemas Ward. New York. 1911.

• The Bread and Flour Regulations 1998, United Kingdom.

External links

• Flour volume vs. weight calculators (US/Metric for all flour types)
• Weight of Baking Ingredients Flour and Water
• Cooking For Engineers - Kitchen Notes: Wheat Flour
• h2g2 entry on Bread Flour
• British Nutrition Foundation - Flour Information