An ingredient; flour is a fine powder made by grinding cereal grains or other suitable edible plant matter high in starch. It is most commonly made from wheat — the word "flour" used without qualification implies wheat flour — but maize (now called corn in many parts of the Western Hemisphere), rye, barley, and rice, amongst many other grasses and non-grain plants (including buckwheat, grain amaranths and many Australian species of acacia), ground legumes and nuts, such as soy, peanuts, almonds, and other tree nuts, are also called flours. Finally flours can be made by grinding the roots of several plants, including cassava, arrowroot and taro. The same substances ground more coarsely are, many cases, called "meal" instead of "flour".

 

Flour is the key ingredient of bread, which is a staple food in many countries, and therefore the availability of adequate supplies of flour has often been a major economic and political issue. Wheat flour is one of the most important foods in European and North American culture, and is the defining ingredient in most European styles of breads and pastries. Regulations in many countries require that wheat flour be enriched to replace nutrients lost in the production of refined flour.

 

Flour, by definition, contains a high proportion of starches, which are complex carbohydrates also known as polysaccharides. Wheat, and some other flours, also contain proteins called gluten. When dough made with wheat flour is kneaded, the gluten molecules cross-link to form a sub-microscopic network that gives the dough an elastic structure. This allows the retention of gas bubbles in an intact structure, resulting in an aerated final product with a soft texture, desirable for breads, cakes and the like.

 

Some people suffer from an intolerance to gluten known as coeliac or celiac disease. Increased awareness of this disorder, as well as a rising belief in the benefits of a gluten-free diet for persons suffering certain other conditions, has led to an increased demand for bread, pasta, and other products made with flours that do not contain gluten.