An ingredient used in many foods, flour is a fine powder made from cereal grain or other starchy food sources. It is most commonly made from wheat, but also corn, rye, barley and rice, amongst many other grasses and even non-grain plants.
Flour is always based on the presence of starches, which are complex carbohydrates.
Usually, the word "flour" used alone refers to wheat flour, which is one of the most important foods in European and American culture. Wheat flour is the main ingredient in most types of breads and pastries. Wheat is so widely used because of an important property: when wheat flour is mixed with water, a complex protein called gluten develops. The gluten development is what gives wheat dough an elastic structure that allows it to be worked in a variety of ways, and which allows the retention of gas bubbles in an intact structure, resulting in a sponge-like texture to the final product.
Types of Flours
The vast majority of today's flour consumption is of wheat flour.
Wheat varieties are typically known as "hard" or "soft", depending on gluten content. Hard wheats are high in gluten, and soft wheats are low. Hard flour, or "bread" flour, is high in gluten and so forms a certain toughness which holds its shape well once baked. Soft flour is 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.
In terms of the parts of the grain (the grass seed) used in flour -- the endosperm or starchy part, the oil-containing germ or protein part, and the bran or fiber part -- there are three general types of flour. "White" flour is made from the endosperm only. "Whole wheat" flour is made from the entire grain. A "germ" flour may also be made from the endosperm and germ, excluding the bran. The germ is sometimes sold by itself, as "wheatgerm".
- Whole wheat flour (or wholemeal flour) is ground from the entire wheat kernel, including the germ and the bran.
- Graham flour is a white flour with coarsely ground bran and wheatgerm mixed back in. It thus contains all three parts of the wheat kernel as whole wheat flour does, but it has a different texture.
- Cake flour, is a milled, bleached flour containing a low amount of gluten (around 7%), and therefore bakes with a fine texture.
- Pastry flour is slightly stronger (higher in gluten) than cake flour.
- All-purpose flour, (known as plain flour in Europe) is a blended white flour containing a medium amount of gluten (around 10%).
- Self-rising flour (also called "Self-raising flour") is an all-purpose flour that has a leavening agent blended into it for convenience.
Flours from other cereals
- Corn flour is an ambiguous term that can mean cornstarch or finely ground cornmeal. Cornmeal which has been leached with lye is called corn masa (masa harina) and is used to make tamales and corn tortillas in Mexican cooking.
- Spelt flour is an alternative to wheat flour. Note: although some people with wheat allergies can tolerate spelt, other wheat-allergic patients have adverse reactions to spelt flour as well. Spelt also has less gluten than wheat, but it is not gluten-free.
- Other grains (cereal and non-cereal) ground into flours include amaranth, barley, buckwheat, millet, oats, quinoa, teff, and triticale.
Flours Made of Legumes, Tubers, Pulses, Etc.
- Chickpea flour (besan) is of great importance in Indian cuisine. Some other legumes ground for flour include soybeans, mung beans, yellow peas, urad dal, and fava beans.