The methods in which grains are processed vary according to the specific grain and geographic area. The following techniques are used in industrialized countries.
Cracking. The grains are put through machines that crack or break them into smaller pieces, which cook more quickly than whole seeds.
Extracting oils. The oil-bearing germ of the grain is pressed or heated to extract the oil.
Extracting starches. The grain is first soaked in a solution containing sulfur dioxide or sodium
hydroxide, ground to remove the bran, and then spun in a centrifuge machine to separate out the starch.
Flaking. The grains are cooked, dried, and rolled through machines to produce flakes of the desired shape and size. Sugar and flavorings may be added to make cereals.
Milling. The grains are sent into grinders or rollers to remove the hulls, bran, and seed germ; at this time, they may also be cracked or crushed into meal or flour.
Parboiling. The grains (usually rice but sometimes wheat) are boiled in water before milling.
Polishing and pearling. After the hulls are removed, an abrasive is used to shape the kernels.
Puffing. The grains are placed in hot rotating cylinders, or puffing guns. Alternatively, the grains are milled and made into a dough that is puffed in an oven.
Rolling. The grains are compressed between large rollers to flatten them, as in rolled oats, or to convert them into flakes.
Shredding. The grains (usually wheat) are cooked, dried, and then squeezed through a grooved cylinder to form long strands.
- Excerpt from "Reader's Digest's Foods That Harm Foods That Heal: An A-Z Guide to Safe and Healthy Eating"