How Is Wheat Processed?

Reaping

Wheat farmers reap the wheat of its kernels after they have fully developed and mostly dried out. The farmers know it is ready when the kernels of wheat have a rich golden brown color. The kernels will contain 15 percent or less moisture at this point. This usually occurs sometime between July and September, depending on the region. In many countries, wheat is still reaped with hand-held instruments such as scythes or sickles. In industrialized countries, the wheat is usually harvested by giant farm machines called combine harvesters, which cut the heads of the wheat off the stalks. The machine then threshes the wheat, beating it to remove the chaff. The wheat farmers then ship the wheat to millers.

Cleaning and Tempering

The millers clean the wheat kernels with mechanical cleaners using a series of disks and streams of water to remove any dust, stones, straw and weeds that might have come in with the kernels. A final water bath separates any heavy items from the wheat, because those items will sink while the wheat floats to the top. The moistened wheat kernels will also toughen the bran coat in a process called tempering. The toughened bran coat will separate from the wheat's endosperm. The water will also soften the endosperm, which will become flour.

Grinding

Millers crack and grind the wheat with their mill's grinding stones or steel rollers. Rollers are the more common way for industrialized countries to grind wheat into flour. The rollers flatten the wheat germ as the wheat is rolled through, which helps the sifters catch the germ. Some millers blow the germ away with streams of air right after the wheat is cracked and the germ is separated away. The germ is blown away when millers make white flour. If they're making whole wheat flour, the bran is ground down with the endosperm. The flour is ground continuously, making it finer and finer. Finally, the flour is passed through sifters, each with progressively smaller mesh, and sometimes as often as 25 times, to ensure very fine flour.

Enriching

Millers bleach the flour and, if all the bran has been removed, they enrich it with supplements such as B vitamins (thiamine, niacin, and riboflavin) and iron. If bran has been left in the flour, then these vitamins and minerals are already in the flour.