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 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 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.
While wheat is the most common base for flour, maize 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.
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 plain flour (also known as all-purpose), self-raising flour (also known as self-rising), 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, biscuits or cookies, and pie crusts.
“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.
The four most common additives used as bleaching/maturing agents in the US 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, 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. 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 colour and baking properties include:
- chlorine dioxide
- 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
Cake flour in particular is nearly always chlorinated. There is at least one flour labeled “unbleached cake flour blend” 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 the manufacturer, this flour is a blend of a more finely milled unbleached wheat flour and cornflour, which makes a better end result than unbleached wheat flour alone (cornflour 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.
All bleaching and maturing agents (with the possible exception of ascorbic acid) have been banned in UK.
Bromination of flour in the US has fallen out of favour 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.
During the process of making flour nutrients are lost. Some of these nutrients may be replaced during refining – the result is enriched flour.
Plain or All-purpose 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 biscuits 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. Bread flour may be made with a hard spring wheat.
Unbleached flour is simply flour that has not undergone bleaching and therefore does not have the colour of “white” flour.
Leavening agents are used with some varieties of flour, especially those with significant gluten content, to produce lighter and softer baked products by embedding small gas bubbles. Self-raising (or self-rising) 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:
- 1 cup (125 g) flour
- 1 teaspoon (3 g) baking powder
- a pinch to ½ teaspoon (1 g or less) salt
Types of Flour
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 protein gluten. “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.
- Arepa Flour – A refined, pre-cooked corn flour
- Atta Flour – A whole-grain wheat flour important in Indian and Pakistani cuisine, used for a range of breads such as roti and chapati.
- Common Wheat Flour (T. aestivum) – The most employed to elaborate bread.
- Durum Wheat Flour (T. durum) is the second most used.
- Maida Flour – A finely milled wheat flour used to make a wide variety of Indian breads such as paratha and naan. Maida is widely used not only in Indian cuisine but also in Central Asian and Southeast Asian cuisine. Though sometimes referred to as “all-purpose flour” by Indian chefs, it more closely resembles cake flour or even pure starch. In India, maida flour is used to make pastries and other bakery items such as bread, biscuits and toast.
- Noodle Flour – A special blend of flour used for the making of Asian-style noodles, made from wheat or rice.
- Semolina – The coarse, purified wheat middlings of durum wheat used in making pasta, breakfast cereals, puddings, and couscous.
- Spelt – An ancient grain, is a hexaploid species of wheat. Spelt dough needs less kneading than common wheat or durum wheat dough. Compared to hard-wheat flours, spelt flour has a relatively low (six to nine percent) protein count, just a little higher than pastry flour. That means that plain spelt flour works well in creating dough for soft foods such as cookies or pancakes. Crackers turn out well because they are made from dough that does not need to rise when baked.
A variety of types of flour and cereals sold at a bazaar in Bishkek, Kyrgyzstan
Rye flour is used to bake the traditional sourdough breads of Germany, Austria, Switzerland, Russia, Czech Republic, Poland and Scandinavia. Most rye breads use a mix of rye and wheat flours because rye does not produce sufficient gluten. Pumpernickel bread is usually made exclusively of rye, and contains a mixture of rye flour and rye meal.
When gluten-free flours are free from contamination with gluten, are suitable for people with gluten-related disorders, such as coeliac disease, non-celiac gluten sensitivity or wheat allergy sufferers, among others. Contamination with gluten-containing cereals can occur during grain harvesting, transporting, milling, storing, processing, handling and/or cooking.
- Acorn Flour – Made from ground acorns and can be used as a substitute for wheat flour. It was used by Native Americans. Koreans also use acorn flour to make dotorimuk.
- Almond Flour – Made from ground almonds.
- Amaranth Flour – A flour produced from ground amaranth grain. It was commonly used in pre-Columbian meso-American cuisine and was originally cultivated by the Aztecs. It is becoming more and more available in speciality food shops.
- Banana Flour – Has traditionally been made of green bananas for thousands of years and is currently popular both as a gluten-free replacement for wheat flour and as a source of resistant starch.
- Bean Flour – A flour produced from pulverised dried or ripe beans. Garbanzo and fava bean flour is a flour mixture with a high nutritional value and strong aftertaste.
- Brown rice flour is of great importance in Southeast Asian cuisine. Edible rice paper can be made from it.
- 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 food made with buckwheat flour. The preparation varies across India. The most famous dishes are kuttu ki puri and kuttu pakoras. In most northern and western states the usual term is kuttu ka atta.
- Cassava flour is made from the root of the cassava plant. In a purified form (pure starch), it is called tapioca flour.
- 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 is made from dried potatoes in various countries of South America.
- Coconut flour is made from ground coconut meat and has the highest fibre content of any flour, having a very low concentration of digestible carbohydrates and thus making an excellent choice for those looking to restrict their carbohydrate intake. It also has a high fat content of about 60 percent.
- Corn (maize) flour is popular in the Southern and Southwestern US, Mexico, Central America, and Punjab regions of India and Pakistan, where it is called makkai ka atta. Coarse whole-grain corn flour is usually called corn meal. Finely ground corn flour that has been treated with food-grade lime is called masa harina 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.
- Cornmeal is very similar to corn flour except in a coarser grind.
- Cornstarch is powdered endosperm of the corn kernel.
- Glutinous rice flour or sticky rice flour is used in east and southeast Asian cuisines for making tangyuan, etc.
- Hemp flour is produced by pressing the oil from the hemp seed and milling the residue. Hemp seed is approximately 30 percent oil and 70 percent residue. Hemp flour does not rise, and is best mixed with other flours. Added to any flour by about 15-20 percent, it gives a spongy nutty texture and flavour with a green hue.
- Mesquite flour is made from the dried and ground pods of the mesquite tree, which grows throughout North America in arid climates. The flour has a sweet, slightly nutty flavour and can be used in a wide variety of applications.
- 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 flavorful 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 pulverised yellow field peas.
- Peanut Flour – Made from shelled cooked peanuts is a high-protein alternative to regular flour.
- Potato starch flour is obtained by grinding the tubers to a pulp and removing the fibre and protein by water-washing. Potato starch (flour) is very white starch powder used as a thickening agent. Standard (native) potato starch needs boiling, to thicken in water, giving a transparent gel. Because the flour is made from neither grains nor legumes, it is used as a substitute for wheat flour in cooking by Jews during Passover, when grains are not eaten.
- Potato Flour – Often confused with potato starch, is a peeled, cooked potato powder of mashed, mostly drum-dried and ground potato flakes using the whole potato and thus containing the protein and some of the fibres of the potato. It has an off-white slight yellowish colour. These dehydrated, dried, potatoes, also called instant mashed potatoes can also be granules or flakes. Potato flour is cold-water-soluble; however, it is not used often as it tends to be heavy.
- Rice Flour – Ground kernels of rice. It is widely used in Western countries especially for people who suffer from gluten-related disorders. Brown rice flour has higher nutritional value than white rice flour.
- Sorghum flour is made from grinding whole grains of the sorghum plant. It is called jowar in India.
- 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 – 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 dust suspended in air is explosive—as is any mixture of a finely powdered flammable substance with air. Some devastating explosions have occurred at flour mills, including an explosion in 1878 at the Washburn “A” Mill in Minneapolis which killed 22 people.
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 thickening gravy and sauces. It is also the base for papier-mâché.
Cornflour is a principal ingredient used to thicken many puddings or desserts, and is the main ingredient in packaged custard.