Flour

Three different kinds of wheat and rye flour.

Flour is a powder which is made by grinding cereal grains, other seeds or roots (like Cassava). It is the main ingredient of bread, which is a staple food for many cultures, 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, North American, Middle Eastern and North African cultures, and is the defining ingredient in most of their 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.[citation needed]Rye flour is an important constituent of bread in much of central/northern Europe.

Etymology

The word "flour" is 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.[1]

History

A field of wheat prior to harvesting.

It was discovered around 9000 BC that wheat seeds could be crushed between simple millstones to make flour.[2] The Romans were the first to grind seeds on cone mills. In 1879, at the beginning of the Industrial Era, the first steam mill was erected in London.[3] In the 1930s, some flour began to be enriched with iron, niacin, thiamine and riboflavin. In the 1940s, mills started to enrich flour and folic acid was added to the list in the 1990s.

Degermed and heat-processed flour

An important 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 six to nine months. In the late 19th century, this process was too short for an industrial production and distribution cycle. As vitamins, micro nutrients and amino acids were completely or relatively unknown in the late 19th century, removing the germ was a brilliant 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 or microwave and blended into flour again.[4]

The FDA has been advised by several cookie dough manufacturers that they have implemented the use of heat-treated flour for their ready-to-bake cookie dough products" to reduce the risk of E. coli contamination.[5]

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, but they are removed before the flour is sold.

Modern mills

Rollermills soon replaced stone grist mills as the production of flour has historically driven technological development, as attempts to make gristmills more productive and less labor-intensive led to the watermill[6] and windmill. These terms are now applied more broadly to uses of water and wind power for purposes other than milling.[7] More recently, the Unifine mill, an impact-type mill, was developed in the mid-20th century.

Composition

Flour being stored in large cloth sacks.

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, self-raising flour, and cake flour including bleached flour. The higher the protein content the harder and stronger the flour and will produce crusty or chewy breads. The lower the protein the softer the flour for better cakes, cookies, and pie crusts.[8]

Unbleached flour

Unbleached flour is simply flour that has not undergone bleaching and therefore does not have the color of "white" flour. An example of this would be the Graham flour. Sylvester Graham was against using bleaching agents, which he considered unhealthy.

Bleached flour

"Refined flour" has had the germ and bran removed and is typically referred to as "white flour". "Bleached flour" is any refined flour with a whitening agent added.

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.

The four most common additives used as bleaching/maturing agents in the USA at this time are:

Potassium bromate (will be listed as an ingredient/additive) - a maturing agent that strengthens gluten development. Does not bleach.

Benzoyl peroxide - bleaches. Does not act as a maturing agent - no effect on gluten

Ascorbic acid (Will be listed as an ingredient/additive, but seeing it in the ingredient list may not be an indication that the flour was matured using ascorbic acid but instead has had a small amount added as a dough enhancer) - Maturing agent that strengthens gluten development. Does not bleach.

Chlorine gas - both a bleaching agent and a maturing agent, but one that weakens gluten development. Chlorination also oxidizes starches in the flour, making it easier for the flour to absorb water and swell - this makes thicker batters and stiffer doughs. For bread, this is bad (because gluten is weakened and bread is heavily dependent on gluten formation), but for cakes, cookies, and biscuits, it's a good thing, because gluten development in these types of baked goods makes them tough. 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.[9] 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.

Cake flours in particular are 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 is a common additive for part of the flour used in cake where actual cake flour is called for but you only have all purpose on hand). However you will still get a denser end result than real cake flour that has been more finely milled, chlorinated, and has a lower protein content in the "cake flour" range of around 6% or so.

All bleaching and maturing agents (with the possible exception of ascorbic acid) have been banned in the EU[10], making cake baking a difficult proposition as heat treated flours that mimic the effects of chlorination are to date available only to bulk bakeries. The home baker in the EU must struggle with the unbleached flours that typically do not lend themselves to the making of light fluffy cakes. At least one home baker has developed a method for heat treating flour at home to break down the starches and make it more acceptable for use in the making of cakes; this process is currently referred to as "Kate Flour" in Internet baking communities, after the woman who continues to develop the process.

Bromation of flour in the USA 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 flours packaged specifically for commercial bakeries are still bromated. Retail bleached flours marketed to the home baker are now mostly either treated via peroxidation or chlorine gas. Current information from Pillsbury is that their bleached flours are treated both with benzoyl peroxide and chlorine gas. Gold Medal states that their bleached flour is either treated with benzoyl peroxide OR it's treated with chlorine gas, but there is no way to tell which process has been used when you buy the flour at the grocery store.

Some other chemicals used as Flour treatment agents to modify color and baking properties include:

Plain flour

Flour that does not have a leavening agent is called plain or all-purpose flour. It is appropriate for most bread and pizza bases. Some cookies are also prepared using this type of flour. Bread flour is high in gluten protein, with 12.5-14% protein compared to 10-12% protein in all-purpose flour. The increased protein binds to the flour to entrap carbon dioxide released by the yeast fermentation process, resulting in a stronger rise.

Self-raising flour

Leavening agents are used with some flours,[11] 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-rising flour is typically composed of the following ratio:

  • 1 cup (110 g) flour
  • 1 teaspoon (3 g) baking powder
  • a pinch to ½ teaspoon (1 g or less) salt

Enriched flour

During the process of making flour nutrients are lost. Some of these nutrients are replaced during refining and the result is "enriched flour".

Common preservatives sometimes added to commercial flour

Calcium propanoate
Sodium benzoate
Tricalcium phosphate
Butylated hydroxyanisole

Types

Wheat flour

More wheat flour is produced than any other flour. Wheat varieties are called "clean," "white," or "brown" or "strong" or "hard" if they have high gluten content, and they are called "soft" or "weak" flour if gluten content is low.

Other flours

A variety of types of flour and cereals sold at a bazaar in Bishkek, Kyrgyzstan

More types of flour

Flour can also be made from soy beans, peanuts, arrowroot, taro, cattails, acorns, quinoa and other non-cereal foodstuffs.

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 is 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 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 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 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:

Ash Protein Wheat flour type
US German French Italian
~0.4% ~9% pastry flour 405 40 00
~0.55% ~11% all-purpose flour 550 55 0
~0.8% ~14% high gluten flour 812 80 1
~1% ~15% first clear flour 1050 110 2
>1.5% ~13% white whole wheat 1600 150 Farina integrale di grano tenero

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. Note that there is no Type 40 French flour. The closest is Type 45.

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. 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.

Other measurable properties of flour as used in baking can be determined using a variety of specialized instruments, such as the Farinograph.

Flammability

Flour dust suspended in air is explosive -- as is any mixture of a finely powdered flammable substance with air[18] (see flour bomb). 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.[19]

Products

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. It is also the base for papier-mâché.

Cornstarch is a principal ingredient of many puddings or desserts.

References

  1. ^ Palmatier, Robert Allen (2000). Food: a dictionary of literal and nonliteral terms. Westport, CT: Greenwood. p. 136. ISBN 0-313-31436-5. http://books.google.com/books?id=OqIe3YFwsFkC. 
  2. ^ Archaeo News -Source: Eurasianet.org (2008-12-9); Published 2008-12-14
  3. ^ [1] -History of flour
  4. ^ Goldkeim - Association to promote vital flour http://www.goldkeim.com/
  5. ^ "Heat treated flour used in raw cookie manufacturing". http://www.oxfordjournals.org//our_journals/cid/prpaper.pdf. 
  6. ^ [2] -Water powered grist mills
  7. ^ [3] -Flour enrichment
  8. ^ [4] Different kinds of flour -Retrieved 2011-04-15
  9. ^ Figoni, Paula I. (2010), How Baking Works, John Wiley & Sons, p. 86, ISBN 0-470-39267-3, http://books.google.co.uk/books?id=XqKF7PqV02cC 
  10. ^ "The Bread and Flour Regulations 1998 – Guidance Notes". Food Standards Agency. 1 June 2008. http://www.food.gov.uk/multimedia/pdfs/breadflourguide.pdf. Retrieved 29 March 2012. 
  11. ^ Self-rising flour -Retrieved 2011-04-15
  12. ^ The Grocer's Encyclopedia - Encyclopedia of Foods and Beverages. By Artemas Ward. New York. 1911.
  13. ^ "Mesquite, the Rediscovered Food Phenomenon". http://chetday.com/mesquiteflour.htm. Retrieved 2010-06-23. 
  14. ^ [5] -Peanut flour
  15. ^ "Idaho Pacific Corporation, The best potatoes that Idaho has to offer". Idahopacific.com. http://www.idahopacific.com/index.html. Retrieved 2011-10-31. 
  16. ^ "Supertoinette page in French on flour types". Supertoinette.com. http://www.supertoinette.com/fiche-cuisine/423/farine-de-ble.html. Retrieved 2011-10-31. 
  17. ^ The author of this phrase has studied baking in France but has no online link to cite for this.
  18. ^ Williamson, George (06-02-2002). "Introduction to Dust Explosions". http://www.chemeng.ed.ac.uk/~emju49/SP2001/webpage/index.html. Retrieved 2006-10-29. [dead link]
  19. ^ "Washburn 'A' Mill Explosion". Minnesota Historical Society Library History Topics. http://www.mnhs.org/library/tips/history_topics/73washburn.html. Retrieved 2006-10-29. 
This article incorporates text from the public domain 1911 edition of The Grocer's Encyclopedia.

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