Flour

Flouris apowdermade bygrindingrawgrains,roots,beans,nuts, orseeds. Flours are used to make many differentfoods.Cerealflour, particularlywheat flour, is the main ingredient ofbread, which is astaple foodfor many cultures.Corn flourhas been important inMesoamericancuisine since ancient times and remains a staple in the Americas.Ryeflour is a constituent of bread in bothCentral EuropeandNorthern Europe.
Cereal flour consists either of theendosperm,germ, andbrantogether (whole-grain flour) or of the endosperm alone (refined flour).Mealis either differentiable from flour as having slightly coarser particle size (degree ofcomminution)or is synonymous with flour; the word is used both ways.
TheCDChas cautioned not to eat raw flour doughs or batters. Raw flour can contain harmful bacteria such asE. coliand needs to be cooked like other foods.
Normal processing of flour from which the outer layers have been removed (white flour) removes nutrients. Such flours, and breads made from them, may be fortified by adding nutrients; this is required by law in the UK.
The English wordflouris originally a variant of the wordflower, and both words derive from theOld Frenchfleurorflour, which had the literal meaning "blossom", and a figurative meaning "the finest". The phrasefleur de farinemeant "the finest part of the flour", since flour resulted from the elimination of coarse and unwanted matter from the grain during milling.
Maizeor corn flour has been important inMesoamericancuisine since ancient times and remains a staple in the Americas.Ryeflour is a constituent of bread in central and northern Europe. Archaeological evidence for making flour (wheatseeds crushed between simplemillstones) dates to at least 6000 BC. In 2018, archaeologists reported finding evidenceof bread making at Shubayqa 1, aNatufianhunter-gatherer site more than 14,000 years old in northwest Jordan. TheRomanswere the first to grind seeds on conemills. In 1786, at the beginning of theIndustrial Era, the first steam-powered flour mill,Albion Mills, Southwark, was completed inLondon.In the 1930s, some flour began to be enriched with iron, niacin, thiamine and riboflavin. In the 1940s, mills started to enrich flour andfolic acidwas added to the list in the 1990s.
An important problem of theIndustrial Revolutionwas the preservation of flour. Transportation distances and a relatively slow distribution system collided with naturalshelf life. The reason for the limited shelf life is thefatty acidsof thegerm, which react from the moment they are exposed to oxygen. This occurs when grain is milled; the fatty acids oxidize and flour starts to becomerancid. Depending on climate and grain quality, this process takes six to nine months. In the late 19th century, this process was too short for an industrial production and distribution cycle. Asvitamins,micronutrientsandamino acidswere completely or relatively unknown in the late 19th century, removing the germ was an effective solution. Without the germ, flour cannot become rancid. Degermed flour became standard. Degermation 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 ormicrowaveand blended into flour again.
Milling of flouris accomplished by grinding grain betweenstonesor 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.
Roller millssoon replaced stonegristmills as the production of flour has historically driven technological development, as attempts to makegristmillsmore productive and less labor-intensive led to thewatermillandwindmill. These terms are now applied more broadly to uses of water and wind power for purposes other than milling.More recently, theUnifine mill, an impact-type mill, was developed in the mid-20th century.
Modern farm equipment allows livestock farmers to do some or all of their own milling when it comes time to convert their own grain crops to coarse meal forlivestock feed. This capability is economically important because the profit margins are often thin enough in commercial farming that saving expenses is vital to staying in business.
Flour contains a high proportion ofstarches, which are a subset of complexcarbohydratesalso known aspolysaccharides. The kinds of flour used in cooking include all-purpose flour (known as plain outside North America), self-rising flour, and cake flour (including bleached flour). The higher the protein content the harder and stronger the flour, and the more it will produce crispy or chewy breads. The lower the protein the softer the flour, which is better for cakes, cookies, and pie crusts.Cereal flour consists either of theendosperm,germ, andbrantogether (whole-grain flour) or of the endosperm alone (refined flour).
"Bleached flour" is "refined" flour with achemical whitening (bleaching) agentadded.  "Refined" flour has had the germ and bran, containing much of the nutritional fibre and vitamins,removed and is often referred to as "white flour".
Bleached flour is artificially aged using a "bleaching" agent, a "maturing" agent, or both. A bleaching agent affects the carotenoids responsible for the natural colour of the flour; a "maturing" agent also affectsglutendevelopment. A maturing agent may either strengthen or weaken gluten development.
The four most common additives used as bleaching/maturing agents in the US are:
Some other chemicals used asflour treatment agentsto modify color and baking properties include:
Common preservatives in commercial flour include:
All bleaching and maturing agents (with the possible exception of ascorbic acid) have been banned in the United Kingdom.
Bromination of flour in the US has fallen out of favor, and while it is not yet actually banned anywhere, few retail flours available to the home baker are bromated anymore.
Many varieties of flour packaged specifically for commercial bakeries are still bromated. Retail bleached flour marketed to the home baker is now treated mostly with either peroxidation or chlorine gas. Current information from Pillsbury is that their varieties of bleached flour are treated both with benzoyl peroxide and chlorine gas. Gold Medal states that their bleached flour is treated either with benzoyl peroxide or chlorine gas, but no way exists to tell which process has been used when buying the flour at the grocery store.
The old method of procuring white or "bleached" flour did not entail the use of chemical agents at all. Rather, thewheat kernelswere moistened with water long enough for the outer kernels of the wheat which contained thebranto soften and, eventually, fall off while grinding.In some places, the leaves of Syrian rue (Peganum harmala) were spread in stratified layers between the layers of grain, and left in such a state for several days, until the fumes emitted from the astringent leaves of the plant caused the outer kernels of the wheat to break down and dissolve, leaving a clean and white flour after grinding.
During the process of making flour, specifically as a result of the bleaching process, nutrients are lost. Some of these nutrients may be replaced during refining – the result is known asenrichedflour. In the UK most flour, and consequently breads made with it, is required to be fortified with added calcium, iron, thiamine (Vitamin B1) and niacin (Vitamin B3); wholemeal flour is exempt as it inherently contains sufficient of these nutrients.
Cake flour is the lowest in gluten protein content, with 6–7%(5–8% from second source) protein to produce minimal binding so the cake "crumbles" easily.
Pastry flour has the second-lowest gluten protein content, with 7.5–9.5%(8–9% from second source) protein to hold together with a bit more strength than cakes, but still produce flaky crusts rather than hard or crispy ones.
All-purpose, or "AP flour", or plain flour is medium in gluten protein content at 9.5–11.5%(10–12% from second source) protein content.  It has adequate protein content for many bread and pizza bases, though bread flour and special 00 grade Italian flour are often preferred for these purposes, respectively, especially by artisan bakers. Some biscuits are also prepared using this type of flour. "Plain" refers not only to AP flour's middling gluten content but also to its lack of any added leavening agent (as in self-rising flour).
Bread flour is typically made fromhard red winter wheatplanted in the fall and harvested in the spring. Hard wheat is high in gluten, a protein that makes dough stretchy. Hard wheat is 11.5–13.5%(12–14% from second source) protein. The increased protein binds to the flour to entrapcarbon dioxidereleased by the yeastfermentationprocess, resulting in a better rise and chewier texture.
Hard is a general term for flours with high gluten protein content, commonly refers to extra strong flour, with 13.5–16%(or 14–15% from some sources) protein (16% is a theoretically possible protein content).  This flour may be used where a recipe adds ingredients that require the dough to be extra strong to hold together in their presence, or when strength is needed for constructions of bread (e.g., some centerpiece displays).
Gluten flour is refined gluten protein, or a theoretical 100% protein (though practical refining never achieves a full 100%). It is used to strengthen flour as needed.  For example, adding approximately one teaspoon per cup of AP flour gives the resulting mix the protein content of bread flour.  It is commonly added to whole grain flour recipes to overcome the tendency of greater fiber content to interfere with gluten development, needed to give the bread better rising (gas holding) qualities and chew.
Unbleached flour is simply flour that has not undergone bleaching and therefore does not have the color of "white" flour. An example isgraham flour, whose namesake,Sylvester Graham, was against using bleaching agents, which he considered unhealthy.
In English-speaking countries, self-raising (or self-rising) flour is commercially available with chemicalleavening agentsalready in the mix.In America, it is also likely to be pre-salted; in Britain this is not the case. The added ingredients are evenly distributed throughout the flour, which aids a consistent rise in baked goods. This flour is generally used for preparing sponge cakes, scones, muffins, etc. It was invented byHenry Jonesand patented in 1845. If a recipe calls for self-raising flour, and this is not available, the following substitution is possible:
Wheat is the grain most commonly used to make flour.Certain varieties may be referred to as "clean" or "white". Flours contain differing levels of the proteingluten. "Strong flour" or "hard flour" has a higher gluten content than "weak" or "soft" flour. "Brown" and wholemeal flours may be made of hard or soft wheat.
When flours do not contain gluten, they are suitable for people withgluten-related disorders, such ascoeliac disease,non-celiac gluten sensitivityorwheat allergysufferers, among others.Contamination with gluten-containing cereals can occur during grain harvesting, transporting, milling, storing, processing, handling and/or cooking.
Flour also can be made fromsoybeans,arrowroot,taro,cattails,manioc,quinoa, and other non-cereal foodstuffs.
In some markets, the different available flour varieties are labeled according to the ash mass that remains after a sample is incinerated in alaboratory oven(typically at 550 °C (1,022 °F) or 900 °C (1,650 °F), seeinternational standardsISO2171 andICC104/1). This is an easily verified indicator for the fraction of the whole grain remains 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 grams (0.071 oz) ash or more per 100 grams (3.5 oz) dry flour. Plain white flour with an extraction rate of 50–60% leaves about 0.4 grams (0.014 oz).
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 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 flour types are not standardized in many countries, the numbers may differ between manufacturers. There is no French type corresponding to the lowest ash residue in the table. The closest is French Type 45.
There is no official Chinese name corresponding to the highest ash residue in the table. Usually such products are imported from Japan and the Japanese namezenryufun(全粒粉) is used, or it is calledquánmài miànfěn(全麥麵粉).
It is possible to determine ash content from some US manufacturers. However, US measurements are based on wheat with a 14% moisture content. Thus, a US flour with 0.48% ash would approximate a French Type 55.
Other measurable properties of flour as used inbakingcan be determined using a variety of specialized instruments, such as thefarinograph.
Flour dust suspended in air isexplosive—as is any mixture of a finely powdered flammable substance with air(seedust explosion). Some devastating explosions have occurred at flour mills, including an explosion in 1878 at theWashburn "A" MillinMinneapolisthat killed 22 people.
TheCDChas cautioned not to eat raw flour doughs or batters. Raw flour can contain bacteria likeE. coliand needs to be cooked like other foods.
Bread,pasta,crackers, manycakes, and many other foods are made using flour. Wheat flour is also used to make arouxas a base for thickening gravy and sauces.
It can also be used as aningredientinpapier-mâchéglue.
Cornstarch is a principal ingredient used to thicken manypuddingsor desserts, and is the main ingredient in packaged custard.