Flour

Flour is a versatile powder used to create a vast array of foods. It serves as a primary ingredient for baked goods and acts as a thickener for many dishes.

Most flour is produced by grinding grains, beans, nuts, seeds, roots, or vegetables in a mill. Cereal flour, specifically wheat flour, is a global staple used to make bread. The word "flour" actually comes from the Old French word "fleur," which means blossom. This is because the term originally described the finest part of the grain after removing coarse matter.

The milling process transforms raw ingredients into fine particles through comminution. This term describes the degree to which something is ground into smaller pieces. If the particles are slightly coarser, the product is often called "meal" instead of flour. Different ingredients require unique preparation steps to reach this state. Nut flour is made by grinding blanched nuts, though walnut flour requires the oil to be extracted first. Soybean flour requires soaking the beans to dehull them before they are dried and ground. For vegetable flour, the plants must be dehydrated before they can be milled.

Cereal flours are categorized by which parts of the grain are kept. Whole-grain flour consists of the endosperm, the germ, and the bran processed together. Refined flour, often called white flour, consists only of the endosperm. This refining process removes the outer layers, which can lead to a loss of nutrients. To fix this, many producers use fortification, which is the process of adding nutrients back into the flour. As of 2016, it is a legal requirement to fortify wheat flour in 86 countries. Some producers also create heat-processed flour by separating the germ and then using steam or microwaves before blending it back in.

Protein content determines how different flours behave during cooking. High-protein flour is strong and hard, which results in chewy or crispy breads. Low-protein flour is much softer, making it ideal for cakes, cookies, and pie crusts. For example, cake flour has a very low protein content of about 6% to 7%. This low level of binding allows the cake to crumble easily. Pastry flour has a slightly higher protein level, typically between 7.5% and 9.5%.

Humanity has a deep history with flour production that spans tens of thousands of years. Archaeologists have found evidence of humans making cereal flour over 32,000 years ago. In Australia, grindstones from the Pleistocene period were discovered at the Madjedbebe site. In northwest Jordan, researchers found evidence of bread making at a Natufian site dating back 14,000 years. The Romans were pioneers in technology, being the first to grind cereals using cone mills. During the Industrial Era, the first steam-powered flour mill, Albion Mills, was completed in London in 1786.

Industrialization brought new challenges, specifically regarding the shelf life of flour. The fatty acids in the germ of the grain react with oxygen, a process called oxidation. This causes the flour to become rancid, often within six to nine months depending on the climate. To prevent this, many industrial mills began removing the germ entirely. While this helped preservation, it also removed vitamins and minerals. This led to the modern practice of enriching or fortifying flour with substances like iron, niacin, thiamine, and riboflavin. In the UK, most flour must be fortified with calcium, iron, thiamine, and niacin.

Flour connects various culinary traditions and scientific advancements across the globe. Corn flour has been a staple in Mesoamerican cuisine since ancient times and remains vital in the Americas. Rye flour is a key component of bread in Central and Northern Europe. In Ethiopia and Eritrea, teff seed flour is used for sourdough and flatbreads. Different regions also use specialized flours like chickpea flour, also known as besan or gram flour, in Indian and Middle Eastern cooking. The drive to make milling less labor-intensive even led to the development of watermills and windmills, technologies that changed how humans use power.