all-purpose flour [awl–pur-puhs flouuhr, flou-er] noun
Wheat-based flour made from either hard wheat (high gluten/protein), soft wheat (low gluten/protein) or a blend of the two, available in bleached and unbleached forms. Total protein is usually around 10% to 12%, with those featuring a higher percentage of soft wheat and bleached flours resulting in slightly less protein. Bleaching flour hastens its aging process, which is a positive quality in that it can improve texture, but some say it leaves a chemical taste. All purpose flour does not contain the bran or the germ of the whole-wheat kernel. U.S. law dictates that flours without the germ must have vitamins added, hence the term “enriched” on the label.
Some sources say that bleached and unbleached flour may be used interchangeably. We recommend that you use the type of flour specified in a recipe. Some bakers insist that bleached flours yield a slightly more delicate result, producing baked goods with more loft, volume and a slightly finer texture, while the counterargument is that baked goods made with bleached flour can taste metallic. We use King Arthur Unbleached All Purpose Flour for recipe development in the test kitchen and love the results it produces. When we use a specific flour, we will tell you in the ingredient listing.