The Milling Process

Manufactured from wheat kernels, flour is the key ingredient found in about 75 percent of all grain products.

Flour varieties are produced by milling and combining different parts and types of wheat grain. As nutrient loss occurs during milling, nutrients are added to flour in amounts equal to those present before processing to make enriched flour. Fortified flour is made by adding nutrients in excess to quantities lost during milling, or additional nutrients are added to improve its nutritive value.

Anatomy of Wheat Kernels

Wheat kernels have three parts: the outer covering or the bran that makes up about 14 percent of the grain’s weight; the germ or embryo that makes up about 3 percent of its weight; and the endosperm, the largest portion of the wheat kernel, which makes up about 83 percent of the grain’s weight. While the bran and germ contain large quantities of the B vitamins, fiber, trace minerals, unsaturated fats, antioxidants and phytonutrients, the main nutrients in the endosperm are carbohydrates, proteins and a small amount of the B vitamins.
Anatomy of a grain

Milling Process

Except for whole-wheat flour, which contains all three parts of the wheat kernel, most flours are made from the endosperm after removal of the bran and germ. This decreases the nutritive value of the flour, as a large proportion of the thiamin, riboflavin, niacin, vitamin B-6, folic acid and iron present in whole-wheat kernels is absent in the finely ground endosperm flour. To compensate for the loss of the nutrients incurred during the milling process, flour is enriched with nutrients. 

Enriched Versus Fortified

The process of enriching flour restores its nutritive value by replacing nutrients lost during milling in amounts similar to those lost. Almost 95 percent of the white flour in the United States is enriched with iron and four of the B vitamins: thiamin, niacin, riboflavin and folic acid. By contrast, fortified flour may contain folic acid in amounts that exceed those present in whole-wheat flour. Calcium, a nutrient that is not naturally present in wheat kernels or whole-wheat flour, is another nutrient that may be present in fortified flour.

Benefit of Enriching and Fortifying Flours

Flour enriched with iron, thiamin, riboflavin, and niacin have been part of the American diet since 1941 and have helped to eradicate beriberi and pellagra from the United States. Although folic acid fortification started only in 1998, its presence in flour is responsible for the decline in the incidence of neural tube defects in babies by 23 percent in the U.S. and by 54 percent in Nova Scotia, Canada.

Whole-Grain Flour

The consumption of fortified and enriched flour as part of a staple diet by most people makes it an ideal source of essential nutrients that may otherwise be lacking in the diet. Consuming whole-wheat flour products has the added advantage of providing fiber, antioxidants and phytonutrients in addition to the vitamins and trace minerals that are naturally present in wheat. Whole-grain products are a healthier option, as they may reduce risk of heart disease, diabetes and even some forms of cancer.