Flour is a powder made by grinding raw grains, roots, beans, nuts, or seeds.

Corn flour has been important in Mesoamerican cuisine since ancient times and remains a staple in the Americas.

Raw flour can contain harmful bacteria such as E. coli and needs to be cooked like other foods.

[2] Maize or corn flour has been important in Mesoamerican cuisine since ancient times and remains a staple in the Americas.

Archaeological evidence for making flour (wheat seeds crushed between simple millstones) dates to at least 6000 BC.

In 2018, archaeologists reported finding evidence[3] of bread making at Shubayqa 1, a Natufian hunter-gatherer site more than 14,000 years old in northwest Jordan.

Transportation distances and a relatively slow distribution system collided with natural shelf life.

The reason for the limited shelf life is the fatty acids of the germ, which react from the moment they are exposed to oxygen.

As vitamins, micronutrients and amino acids were completely or relatively unknown in the late 19th century, removing the germ was an effective solution.

This capability is economically important because the profit margins are often thin enough in commercial farming that saving expenses is vital to staying in business.

The higher the protein content the harder and stronger the flour, and the more it will produce crispy or chewy breads.

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.

Bread flour is typically made from hard red winter wheat planted in the fall and harvested in the spring.

The increased protein binds to the flour to entrap carbon dioxide released by the yeast fermentation process, resulting in a better rise and chewier texture.

This flour may be used where a recipe adds ingredients that require the dough to be extra strong to hold together in their presence, or when strength is needed for constructions of bread (e.g., some centerpiece displays).

It is commonly added to whole grain flour recipes to overcome the tendency of greater fiber content to interfere with gluten development, needed to give the bread better rising (gas holding) qualities and chew.

In English-speaking countries, self-raising (or self-rising) flour is commercially available with chemical leavening agents already in the mix.

The added ingredients are evenly distributed throughout the flour, which aids a consistent rise in baked goods.

[23][24][25][26] Contamination with gluten-containing cereals can occur during grain harvesting, transporting, milling, storing, processing, handling and/or cooking.

[26][27][28] Flour also can be made from soybeans, arrowroot, taro, cattails, manioc, quinoa, and other non-cereal foodstuffs.

In some markets, the different available flour varieties are labeled according to the ash mass that remains after a sample is incinerated in a laboratory oven (typically at 550 °C (1,022 °F) or 900 °C (1,650 °F), see international standards ISO 2171 and ICC 104/1[35]).

Usually such products are imported from Japan and the Japanese name zenryufun (全粒粉) is used, or it is called quánmài miànfěn (全麥麵粉).