Shopping for flour isn't as easy as it seems. The baking aisle at most major stores boast dozens of types and brands that all promise to make your baked goods the best ever. Two common types are all-purpose and self-rising. You cannot use them interchangeably in recipes, so knowing the difference is crucial to successful cooking and baking.
A Kitchen Staple
As the name suggests, all-purpose flour is suitable for almost any purpose. Use it to make breads, pie crust, pizza dough, cookies, cakes, biscuits or sauces. All-purpose flour is suited to pretty much any recipe and will turn out a fair product, but perhaps not a superior one. All-purpose flour is commonly made from hard red winter wheat, but some brands -- especially Southern ones known for their powdery, fine texture -- are made only from soft red winter wheat. Some brands of all-purpose flour contain a mix of the two types of wheat.
It's In the Protein
Flour contains protein in the form of gluten. A high-protein flour makes a French baguette chewy and a low-protein flour makes a cake light and tender. Most all-purpose flour falls somewhere in the middle range with about 11 to 13 percent protein, although Southern varieties can be as low as 9 percent. Low-protein cake flours have just 8 percent protein while sturdy bread flours have about 14 percent.
Rise on Up
Self-rising flour tends to have a lower protein content, about 9 to 10 percent, so it turns out light and fluffy muffins, biscuits and quick breads. Another feature of self-rising flour is the addition of baking powder and salt. This addition means you can save a step in your favorite recipe and not add the baking powder and salt, but if your recipe wouldn't call for baking powder, self-rising flour is a no-no. For example, self-rising flour's low-protein content and baking powder would be a disaster in yeast breads.
All-purpose and self-rising flour come in bleached and unbleached varieties. Millers use the bleaching process to speed up the natural oxidizing process which can take weeks, but is essential to a high-quality, high-functioning flour. The bleaching process involves adding chemicals such as benzoyl peroxide to the flour or exposing it to chlorine dioxide gas. Unbleached flour is permitted to oxidize naturally, which delays getting the flour to the marketplace. Whole wheat all-purpose flour is made from the germ and the bran of the wheat kernel. It tends to turn out heavier baked goods when used as the sole flour source.