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 health-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. " All-purpose flour comes in two basic forms — bleached and unbleached — that can be used interchangeably. Flour can be bleached either naturally, as it ages, or chemically. Most flour on the market today is presifted, requiring only that it be stirred, then spooned into a measuring cup and leveled off. Bread flour is an unbleached, specially formulated, high-gluten blend of 99. 8 percent hard-wheat flour, a small amount of malted barley flour (to improve yeast activity) and vitamin C or potassium bromate (to increase the gluten's elasticity and the dough's gas retention). It is ideally suited for yeast breads. The fuller-flavored whole-wheat flour contains the wheat germ, which means that it also has a higher fiber, nutritional and fat content. Because of the latter, it should be stored in the refrigerator to prevent rancidity. Cake or pastry flour is a fine-textured, soft-wheat flour with a high starch content. It makes particularly tender cakes and pastries. Self-rising flour is an all-purpose flour to which baking powder and salt have been added. It can be substituted for all-purpose flour in yeast breads by omitting the salt and in quick breads by omitting both baking powder and salt. Instant flour is a granular flour especially formulated to dissolve quickly in hot or cold liquids. It's used mainly as a thickener in sauces, gravies and other cooked mixtures. Gluten flour is high-protein, hard-wheat flour treated to remove most of the starch (which leaves a high gluten content). It's used mainly as an additive to doughs made with low-gluten flour (such as rye flour), and to make low-calorie "gluten" breads. All flour should be stored in an airtight container. All-purpose and bread flour can be stored up to 6 months at room temperature (about 70°F). Temperatures higher than that invite bugs and mold. Flours containing part of the grain's germ (such as whole wheat) turn rancid quickly because of the oil in the germ. Refrigerate or freeze these flours tightly wrapped and use as soon as possible. Other grains — such as barley, buckwheat, corn, oats, rice, rye and triticale — are also milled into flours. flour v. To lightly coat a food, utensil or baking container with flour. Flouring food to be fried facilitates browning, and coating foods that tend to stick together (such as chopped dried apricots) helps separate the pieces. Flouring a pie, pastry or cookie dough will prevent it from sticking to a work surface; flouring your hands, rolling pin or work surface prevents dough from sticking. Dusting greased baking pans with flour provides for easy removal of cakes, breads and other baked goods.