Milling wheat entails releasing the starchy endosperm contained in the wheat grain. This transformation, called milling, is necessary to make cereals edible. Milling requires a lot of time and energy. In Neolithic homes, flour was prepared for each meal using a pestle and mortar. Originally performed by hand, this tedious task is now carried out by industrial mills.
From artisanal to industrial milling
In Neolithic homes, flour was prepared for each meal using a pestle and mortar, and used to make porridge and pancakes.
The first mills were, operated manually and consisted of two stones, one flat, called the bed, on which the grains were placed, and the other a small round stone, the grindstone, which was gripped in the hand to crush the grains. The invention of the wheel resulted in ingenious systems such as that of a millstone rotating above a fixed stone. Mills relied on the driving force of animals or humans to function.
The Romans were the first to use hydraulic power with paddle wheel mills. In the Middle Ages, windmills were imported from the East by knights returning from the Crusades. The energy used was different from that used by watermills, but the mechanism was the same: a large fixed millstone on which the grain is crushed by the rotating runner stone. The miller’s work involved crushing the wheat grains and delivering them either to people’s homes or to bakers, who bolted (sieved) them, to separate the flour from the bran.
The first steam mill appeared in England towards the end of the 18th century. In the latter half of the 19th century, the arrival of roller mills revolutionised flour mills. These rollers replaced millstones and gave rise to a new milling industry. This new milling system, presented at the 1878 Paris world fair is still used in modern-day mills, although nowadays the milling process is automatic and controlled by computer. The miller’s role is to oversee the proper functioning of the machines. Each stage of milling is analysed to help optimise the quality of the flour.
From wheat grain to flour
In order for us to eat wheat, it must first be transformed. This transformation (milling) means extracting the starchy endosperm from the wheat grain by separating it from the protective outer shell (the bran) and the germ. The germ is transformed into oil.
In modern mills, grains of wheat are crushed between large metal fluted rollers which have replaced the millstones of the past. This mechanical action opens up the grains. The product is then sieved to separate the flour (the endosperm) from the larger, dark pieces, the bran (the shell). Sophisticated sieves, called plansifters, separate the different kinds of flour and grade them according to size. Finally, since the act of separating the bran and the germ during milling results in the loss of nutrients, the flour is fortified by adding various vitamins and minerals.
Different kinds of flour and milling products
The various stages of the milling process fragment the wheat grains. Different sorts of flour are made from these fragments. A type of flour is defined by its extraction rate which indicates the percentage of the whole grain present in the flour. Thereby, fine white flour is made up solely of the central part of the seed (the endosperm), whereas wheatmeal is flour made up of all the components of the whole grain, except the germ.
Durum wheat is crushed and reduced to semolina used for the production of pasta and couscous.
Cereals such as rye, buckwheat, maize and barley are also transformed into flour.
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