A Short Look at Milling

Once the wheat has been harvested, and before milling, it undergoes a resting phase called “sweating.” During this time, which generally lasts about six weeks, a number of subtle metabolic changes occur that will improve the milling quality of the grain, as well as slightly reduce the moisture in the wheat. Moisture in the field may be as high as 17 percent or more; once the grain is milled, the moisture level is close to 14 percent.

Once the sweating phase is complete, barges, trucks, or freight trains transport the wheat to the mill. It now goes through a series of steps to remove any iron or steel particles, stones, sticks, stray grains such as rye or oats (which are considered to be “weeds” by wheat farmers), and any other foreign matter that could impair the purity of the milled flour. Once this phase is completed, the wheat berries go through the process called “tempering.” During tempering, moisture is added to the wheat, usually in the form of chlorinated water, to prevent microbial growth. This moisture toughens the bran layers and softens the endosperm. The result is an easier separation of the bran from the endosperm during milling. How long to temper the wheat? In the United States, around 6 hours is a typical tempering time. In Europe, tempering might last 24 to 48 hours.