Glossary: flour n.

The finely ground and sifted meal of any of various edible grains. Giant steel or stone rollers are used to break and grind the grain. Most supermarkets carry steel-ground flour, meaning it's crushed with huge, high-speed steel rollers or hammers. The heat that is generated with these high-velocity machines strips away the wheat germ and destroys valuable vitamins and enzymes. The more naturally nutritious stone-ground flour is produced by grinding the grain between two slowly moving stones. This process crushes the grain without generating excess heat and separating the germ. Stone-ground flours must usually be purchased in natural food stores, though some large supermarkets also carry them. A flour can range in texture from coarse to extremely soft and powdery, depending on the degree of bolting (sifting) it receives at the mill. Wheat is the most common source of the multitude of flours used in cooking. It contains gluten, a protein that forms an elastic network that helps contain the gases that make mixtures (such as doughs and batters) rise as they bake. All-purpose flour is made from a blend of high-gluten hard wheat and low-gluten soft wheat. It's a fine-textured flour milled from the inner part of the wheat kernel and contains neither the germ (the sprouting part) nor the bran (the outer coating). U.S. law requires that all flours not containing wheat germ must have niacin, riboflavin, thiamin and iron added. (Individual millers sometimes also add vitamins A and D.) These flours are labeled 'enriched.'

From THE NEW FOOD LOVERS COMPANION, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.