Flour

Flour is a powder used to make many different foods, including baked goods, as well as thickening dishes. It is made by grinding grains, beans, nuts, seeds, roots, or vegetables using a mill.

Cereal flour, particularly wheat flour, is the main ingredient of bread, which is a staple food for many cultures. Archaeologists have found evidence of humans making cereal flour over 14,000 years ago. Other cereal flours include corn flour, which has been important in Mesoamerican cuisine since ancient times and remains a staple in the Americas, while rye flour is a constituent of bread in both Central Europe and Northern Europe. Cereal flour consists either of the endosperm, germ, and bran together, known as whole-grain flour, or of the endosperm alone, which is known as refined flour. 'Meal' is technically differentiable from flour as having slightly coarser particle size, known as degree of comminution. However, the word 'meal' is synonymous with 'flour' in some parts of the world. The processing of cereal flour to produce white flour, where the outer layers are removed, means nutrients are lost. Such flour, and the breads made from them, may be fortified by adding nutrients. As of 2016, it is a legal requirement in 86 countries to fortify wheat flour.^[1]

Nut flour is made by grinding blanched nuts, except for walnut flour, for which the oil is extracted first. Nut flour is a popular gluten-free alternative, being used within the "keto" and "paleo" diets. None of the nuts' nutritional benefits are lost during the grinding process.^[2] Nut flour has traditionally been used in Mediterranean and Persian cuisine.

Bean flours are made by grinding beans that have been either dried or roasted. Commonly used bean flours include chickpea, also known as gram flour or besan, made from dried chickpeas and traditionally used in Mediterranean, Middle Eastern and Indian cuisine.^[3] Soybean flour is made by soaking the beans to dehull them, before they are dried (or roasted to make kinako) and ground down; at least 97% of the product must pass through a 100-mesh standard screen to be called soya flour, which is used in many Asian cuisines.^[4]

Seed flours like teff are traditional to Ethiopia and Eritrea, where they are used to make flatbread and sourdough,^[5] while buckwheat has been traditionally used in Russia, Japan and Italy.^[6] In Australia, millstones to grind seed have been found that date from the Pleistocene period.

Root flours include arrowroot and cassava. Arrowroot flour (also known as arrowroot powder) is used as a thickener in sauces, soups and pies, and has twice the thickening power of wheat flour.^[7] Cassava flour is gluten-free and used as an alternative to wheat flour.^[8] Cassava flour is traditionally used in African, South and Central American and Caribbean food.

Vegetable flour is made from dehydrating vegetables before they are milled. These can be made from most vegetables, including broccoli, spinach, squash and green peas. They are rich in fibre and are gluten-free.^[9] There have been studies to see if vegetable flour can be added to wheat-flour-based bread as an alternative to using other enrichment methods.^[10]