U.S. law requires that all flours not containing wheat germ must have niacin, riboflavin, thiamin and iron added. 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. Because of the latter, it should be stored in the refrigerator to prevent rancidity. It makes particularly tender cakes and pastries.
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. All flour should be stored in an airtight container. Temperatures higher than that invite bugs and mold. Refrigerate or freeze these flours tightly wrapped and use as soon as possible. To lightly coat a food, utensil or baking container with flour.