Flour Introduction and Composition Introduction

Flour is a powder made by grinding raw grains or roots and used to make many different foods. Cereal flour is the main ingredient of bread, which is a staple food for most cultures. Wheat flour is one of the most important ingredients in Oceanic, European, South American, North American, Middle Eastern, North Indian and North African cultures, and is the defining ingredient in their styles of breads and pastries.

Wheat is the most common base for flour. Corn flour has been important in Mesoamerican cuisine since ancient times and remains a staple in the Americas. Rye flour is a constituent of bread in central Europe.

Cereal flour consists either of the endosperm, germ, and bran together (whole-grain flour) or of the endosperm alone (refined flour). Meal is either differentiable from flour as having slightly coarser particle size (degree of comminution) or is synonymous with flour; the word is used both ways. For example, the word cornmeal often connotes a grittier texture whereas corn flour connotes fine powder, although there is no codified dividing line.

Composition

Flour contains a high proportion of starches, which are a subset of complex carbohydrates also known as polysaccharides. The kinds of flour used in cooking include all-purpose flour (known as plain outside North America), self-rising flour (known as self-raising outside North America), and cake flour including bleached flour. The higher the protein content the harder and stronger the flour, and the more it will produce crusty or chewy breads. The lower the protein the softer the flour, which is better for cakes, cookies, and pie crusts.[9]

Bleached flour

Main article: Flour bleaching agent
“Bleached flour” is any refined flour with a whitening agent added. “Refined flour” has had the germ and bran removed and is typically referred to as “white flour”.

Bleached flour is artificially aged using a bleaching agent, a maturing agent, or both. A bleaching agent would affect only the carotenoids in the flour; a maturing agent affects gluten development. A maturing agent may either strengthen or weaken gluten development.

Additives

The four most common additives used as bleaching/maturing agents in the US are:

potassium bromate – Listed as an ingredient, it is a maturing agent that strengthens gluten development. It does not bleach.
benzoyl peroxide – Bleaches, but does not act as a maturing agent. It has no effect on gluten.
ascorbic acid Listed as an ingredient, either as an indication that the flour was matured using ascorbic acid or that a small amount is added as a dough enhancer. It is a maturing agent that strengthens gluten development, but does not bleach.
chlorine gas – Used as both a bleaching agent and a maturing agent. Weakens gluten development and oxidizes starches, making it easier for the flour to absorb water and swell, resulting in thicker batters and stiffer doughs. The retarded gluten formation is desirable in cakes, cookies, and biscuits as it would otherwise make them tougher and bread-like. The modification of starches in the flour allows the use of wetter doughs (making for a moister end product) without destroying the structure necessary for light fluffy cakes and biscuits.[10] Chlorinated flour allows cakes and other baked goods to set faster, rise better, the fat to be distributed more evenly, with less vulnerability to collapse.
Some other chemicals used as flour treatment agents to modify color and baking properties include:

chlorine dioxide (unstable to be transported in the U.S.)
calcium peroxide
azodicarbonamide or azobisformamide (synthetic)
Atmospheric oxygen causes natural bleaching.
Common preservatives in commercial flour include:

calcium propanoate
sodium benzoate
tricalcium phosphate
butylated hydroxyanisole
Frequency of additives
Cake flour in particular is nearly always chlorinated. There is at least one flour labeled “unbleached cake flour blend” (marketed by King Arthur) that is not bleached, but the protein content is much higher than typical cake flour at about 9.4% protein (cake flour is usually around 6% to 8%). According to King Arthur, this flour is a blend of a more finely milled unbleached wheat flour and cornstarch, which makes a better end result than unbleached wheat flour alone (cornstarch blended with all-purpose flour commonly substituted for cake flour when the latter is unavailable). The end product, however, is denser than would result from lower-protein, chlorinated cake flour.[citation needed]

All bleaching and maturing agents (with the possible exception of ascorbic acid) have been banned in the United Kingdom.[11]

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 there is no way to tell which process has been used when buying the flour at the grocery store.

Enriched flour

Main article: Enriched flour
During the process of making flour nutrients are lost. Some of these nutrients may be replaced during refining – the result is enriched flour.

Cake flour

Cake flour is the lowest in gluten protein content, with 6-7%[12] (5-8% from second source[13]) protein to produce minimal binding so “the cake crumbles” easily.

Pastry flour

Pastry flour has the second lowest gluten protein content, with 7.5-9.5%[12] (8-9% from second source[13]) protein to hold together with a bit more strength than cakes, but still produce flaky crusts rather than hard or crisp ones.

Plain or all-purpose flour

All-purpose, or “AP flour”, or plain flour is medium in gluten protein content at 9.5-11.5%[12](10-12% from second source[13]) 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

Bread flour, or strong flour is high in gluten protein, with 11.5-13.5%[12](12-14% from second source[13]) protein. The increased protein binds to the flour to entrap carbon dioxide released by the yeast fermentation process, resulting in a stronger rise and more chewy crumb. Bread flour may be made with a hard spring wheat.

Hard flour

Hard is a general term for flours with high gluten protein content, commonly refers to extra strong flour, with 13.5-16%[12] (or 14-15% from some sources) protein (16% is a theoretically possible protein content[12]). 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

Gluten flour is the 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 it 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

Unbleached flour is simply flour that has not undergone bleaching and therefore does not have the color of “white” flour. An example is Graham flour, whose namesake, Sylvester Graham, was against using bleaching agents, which he considered unhealthy.

Self-rising flour

Leavening agents are used with some varieties of flour,[14] especially those with significant gluten content, to produce lighter and softer baked products by embedding small gas bubbles. Self-rising (or self-raising) flour is sold premixed with chemical leavening agents. The added ingredients are evenly distributed throughout the flour which aids a consistent rise in baked goods. This flour is generally used for preparing scones, biscuits, muffins, etc. It was invented by Henry Jones and patented in 1845. Plain flour can be used to make a type of self-rising flour although the flour will be coarser. Self-raising flour is typically composed of the following ratio

Read More: https://en.wikipedia.org/wiki/Flour