A stroll down the supermarket’s baking aisle reminds me that there are more than a few kinds of flour to choose from. To decide which type is best for the kind of baking you do, it helps to understand that flour is made up of carbohydrates (or starch), proteins, and in the case of whole-wheat flour, a bit of fat. Of these three nutrients, protein matters most to the baker. The proteins in wheat are called gluten-forming proteins, and the quantity and quality of these proteins determines how a flour will perform in the kitchen.
A high percentage of protein means a harder (stronger) flour best suited to chewy, crusty breads and other yeast-risen products. Less protein means a softer flour, best for tender and chemically leavened baked goods, like pie crusts, cakes, cookies, and biscuits.
Since the protein content of wheat can range from 5% to 15%, the flour industry has established labeling standards that help us find the right flour for our needs.
How much protein is in your flour?
Unless you’re an avid bread or cake baker, an all-purpose flour is probably your best choice. It’s made with an average protein content to be versatile enough for everything from cakes to breads. In general, you may find that cakes made with all-purpose flour are a bit tougher and less delicate than those made with a softer pastry or cake flour. Likewise, breads made with all-purpose flour may be a bit softer and flatter than those made with bread flour. But overall, these differences should be slight for the casual baker.
If a recipe calls for a certain type of flour and all you have is all-purpose, some manufacturers recommend using 1 tablespoon more per cup when making breads and 1 tablespoon less per cup for cookies and biscuits. This will increase or decrease the total amount of protein going into the batter or dough.
Within categories of flour, there’s also a range in amount of protein between different brands. It’s also important to know that, despite its high protein content, whole-wheat flour has to be mixed with all-purpose flour to form a light loaf (the bran in whole-wheat flour tends to cut gluten strands, reducing elasticity).
Beyond the differences in protein content, there are also a few distinct specialty flours. Cake flour, the lowest protein flour, has undergone a special bleaching process (distinct from the process used for other white flours) that increases the flour’s ability to hold water and sugar. This means that when you’re making baked goods with a high ratio of sugar to flour, the flour will be better able to hold its rise and will be less liable to collapse.
Self-rising flour is a relatively soft all-purpose flour to which baking powder and salt have been added. Manufacturers suggest using it for biscuits, quick breads, and cookies and eliminating the baking powder and salt called for in the recipe.