How Is Flour Made?
We would not have any bread (or many other foods) if we didn’t have flour. Flour is made by grinding, or milling, cereal grains into fine powder. Most flour is made from wheat.
To make flour, the wheat kernels are ground between large steel rollers. The ground-up wheat is then sifted between screens to separate the white floury part from the rest of the kernel.
Fine white flour has been ground and sifted several times. Whole-wheat flour is wheat flour that contains almost the whole grain. It has not been ground and sifted as many times.
The earliest archaeological evidence for wheat seeds crushed between simple millstones to make flour dates to 6000 BC. The Romans were the first to grind seeds on cone mills. In 1879, at the beginning of the Industrial Era, the first steam mill was erected in London.
In the 1930s, some flour began to be enriched with iron, niacin, thiamine and riboflavin. In the 1940s, mills started to enrich flour and folic acid was added to the list in the 1990s.
Milling of flour is accomplished by grinding grain between stones or steel wheels. Today, “stone-ground” usually means that the grain has been ground in a mill in which a revolving stone wheel turns over a stationary stone wheel, vertically or horizontally with the grain in between.
Although flour can be made from a wide variety of plants, the vast majority is made from wheat. Dough made from wheat flour is particularly well suited to baking bread because it contains a large amount of gluten, a substance composed of strong, elastic proteins.
The gluten forms a network throughout the dough, trapping the gases which are formed by yeast, baking powder, or other leavening agents. This causes the dough to rise, resulting in light, soft bread.
Flour has been made since prehistoric times. The earliest methods used for producing flour all involved grinding grain between stones. These methods included the mortar and pestle (a stone club striking grain held in a stone bowl), the saddlestone (a cylindrical stone rolling against grain held in a stone bowl), and the quern (a horizontal, disk-shaped stone spinning on top of grain held on another horizontal stone). These devices were all operated by hand.
The millstone, a later development, consisted of one vertical, disk-shaped stone rolling on grain sitting on a horizontal, disk-shaped stone. Millstones were first operated by human or animal power. The ancient Romans used waterwheels to power millstones. Windmills were also used to power millstones in Europe by the twelfth century.
The first mill in the North American colonies appeared in Boston in 1632 and was powered by wind. Later mills in the region used water. The availability of water power and water transportation made Philadelphia, Pennsylvania, the center of milling in the newly independent United States. The first fully automatic mill was built near Philadelphia by Oliver Evans in 1784.
During the next century, the center of milling moved as railroads developed, eventually settling in Minneapolis, Minnesota. During the nineteenth century numerous improvements were made in mill technology. In 1865, Edmund La Croix introduced the first middlings purifier in Hastings, Minnesota. This device consisted of a vibrating screen through which air was blown to remove bran from ground wheat. The resulting product, known as middlings or farina, could be further ground into high-quality flour.
In 1878, the first important roller mill was used in Minneapolis, Minnesota. This new type of mill used metal rollers, rather than millstones, to grind wheat. Roller mills were less expensive, more efficient, more uniform, and cleaner than millstones. Modern versions of middlings purifiers and roller mills are still used to make flour today.