In the culinary sense, flour is a powder made of cereal grains, other seeds, 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, 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.
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.
More wheat flour is produced than any other flour. Wheat varieties are called "clean," "white," or "brown" if they have high gluten content, and they are called "soft" or "weak" flour if gluten content is low. Hard flour, or bread flour, is high in gluten, with 12% to 14% gluten content, and has elastic toughness that holds its shape well once baked. Soft flour is comparatively low in gluten and so results in a finer texture. Soft flour is usually divided into cake flour, which is the lowest in gluten, and pastry flour, which has slightly more gluten than cake flour.
Types of wheat flour
- All-purpose or plain flour is a blended wheat white flour with a protein content lower than bread flour, ranging between 9% and 12%. Depending on brand or the region where it is purchased it may be composed of all hard or soft wheats or a blend of the two, and can range from low protein content to moderately high. It is marketed as an inexpensive alternative to bakers' flours which is acceptable for most household baking needs.
- Bleached flour is a white flour treated with flour bleaching agents to whiten it (freshly milled flour is yellowish) and to give it more gluten-producing potential. Oxidizing agents are usually employed, most commonly organic peroxides like acetone peroxide or benzoyl peroxide, nitrogen dioxide, or chlorine. A similar effect can be achieved by letting the flour oxidize with oxygen in the air ("natural aging") for approximately 10 days; however, this process is more expensive due to the time required.
- Bread Flour is always made from hard wheat, usually hard spring wheat. It has a very high protein content, between 10% and 13%, making it excellent for yeast bread baking. It can be white or whole wheat or in between.
- Bromated flour has a maturing agent added. The agent's role is to help with developing gluten, a role similar to the flour bleaching agents. Bromate is usually used. Other choices are phosphates, ascorbic acid, and malted barley. Bromated flour has been banned in much of the world, as bromate is classified as possibly carcinogenic in humans (Group 2B) by the International Agency for Research on Cancer (IARC)., but remains available in the United States.
- Cake flour is a finely milled white flour made from soft wheat. It has very low protein content, between 8% and 10%, making it suitable for soft-textured cakes and cookies. The higher protein content of other flours would make the cakes tough. Highly sifted cake flours may require different volume amounts in recipes than all-purpose flour. Related to cake flour are masa harina (from maize), maida flour (from wheat or tapioca), and pure starches.
- Graham flour is a special type of whole-wheat flour. The endosperm is finely ground, as in white flour, while the bran and germ are coarsely ground. Graham flour is uncommon outside of the USA and Europe. It is the basis of true graham crackers. Many graham crackers on the market are actually imitation grahams because they do not contain graham flour or even whole-wheat flour.
- Pastry flour or cookie flour or cracker flour has slightly higher protein content than cake flour but lower than all-purpose flour. Its protein content ranges between 9% and 10%. It is available as a white flour, a whole-wheat flour, or a white flour with the germ retained but not the bran. It is suitable for pie pastry and tarts, some cookies, muffins, biscuits and other quick breads. Flour is shaken through a sieve to reduce the amount of lumps for cooking pastry.
- Self-rising or self-raising flour is white flour that is sold premixed with chemical leavening agents. It was invented by Henry Jones. Self-rising flour is typically composed of the following ratio:
- 1 cup (100 g) flour
- 1½ teaspoon (3 g) baking powder
- a pinch to ½ teaspoon (1 g or less) salt
- Sharp flour is produced in Fiji and primarily used in Indian cuisine.
- Spelt flour is a flour produced from the type of wheat called spelt. It is less commonly used in modern cooking than other wheat varieties. It is still used for specialty baking.
- Tang flour or wheat starch is a type of wheat flour used primarily in Chinese cooking for making the outer layer of dumplings and buns. It is also used in Vietnamese cuisine, where it is called bột lọc trong.
- Almond flour is made from ground almond nuts.
- 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.
- 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.
- Cassava flour is made from the root of the cassava plant. In a purified form (pure starch), it is called tapioca flour (see in list, below)
- 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 and Pakistan, where it called as Makkai Ka Atta. 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.
- Cornstarch is powdered endosperm of the corn kernel.
- Glutinous rice flour or sticky rice flour, used in east and southeast Asian cuisines for making tangyuan etc.
- Maida flour is 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 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 and protein by water-washings. 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 grain nor legume, it is used as 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, 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; having an off-white slight yellowish colour. Dehydraded potatoes or instant mashed potatoes can also be granular, flakes. Potato flour is cold water soluble.
- 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.