The processing of whole grains of wheat to white flour takes many steps. The wheat kernel is composed of an outer layer called the “bran,” which is rich in B vitamins, minerals, and fiber. The next layer is the wheat germ, which is the sprouting portion of the kernel. The wheat germ is a rich source of vitamins B and E. The next layer is the endosperm, which is the starch or food supply for the sprouting seed. The endosperm makes up approximately 80 to 85 percent of the grain. The germ is about 3 percent, and the bran about 15 percent.
Refined white flour is pure endosperm or starch. Both the bran and the germ have been removed, along with approximately 80 percent of the wheat’s nutrients. The endosperm has far lower B vitamin and mineral content than the germ and bran, and also significantly less fiber.
Not only have 80 percent of the nutrients been removed, but the milling process involves such high temperatures that the remaining grain is damaged by oxidation. Flour at the end of the refining process actually has a grayish appearance from the oxidation. That color, of course, would be offensive to most consumers. So a chemical agent such as chlorine dioxide, acetone peroxide, or benzoyl peroxide is used to bleach the flour to make it white. This bleaching process destroys even more of the few vitamins that remain. In addition, the bleaches can react with fatty acids to produce peroxides that are toxic and that can cause free-radical reactions. (Just compare these bleach products to the labels on chemical bleaches in your home such as Clorox!) In all, the milling and bleaching processes used today remove some twenty-two important nutrients from our bread, including fiber, vitamins, and minerals.