When you're taking on a baking project, there are many different types of flour at your disposal. In fact, at this very moment I have 6 different types of flour in my pantry. I've got the staples—all-purpose flour (AP), cake flour, and bread flour—then some fun additions: whole wheat flour, almond flour, cassava flour.
Why is my pantry stocked with so many different types of flour? First, because I love to take on new baking challenges, but mainly because each type of flour suits a particular purpose. Some of these are self-explanatory (I use bread flour to bake bread, all-purpose flour for flour tortillas); other more niche flours require a bit of explanation (almond flour for macarons, cassava flour for flatbreads). But how can you tell which flour is best for your specific project?
Each flour has its strengths and weaknesses. I'm here to break down everything you need to know about 2 specific types of flour: Cake flour and all-purpose flour. When should you use one and not the other? Should you only use cake flour in cakes? Don't worry: I have answers to all your baking questions.
The main difference between types of flour is in the gluten content. Flour can be made from high-protein wheats ("hard wheat") or low-protein wheats ("soft wheat"). The more protein in the flour, the more gluten develops, which leads to more strength, volume, and elasticity in the final baked product. For example, bread flour—the strongest type of flour—is made from hard wheat, resulting in the denser, chewy texture desirable in bread. These qualities, however, are not desirable when baking more delicate pastries or cakes, where you want a tender crumb.
On the other end of the spectrum, cake flour—made from soft wheat—has the lowest protein content of all flours (7-9% protein). Since its gluten proteins are very weak, cake flour is often used to make soft, tender baked goods like cakes, pastries, or biscuits. A chlorination process further breaks down cake flour's gluten, creating a flour that's even more delicate.
All-purpose flour is made from a mixture of hard and soft wheat. In terms of structure, all-purpose flour has a moderate protein content (10-13% protein), so it holds its shape without delivering the same density or level of gluten development as bread flour. All-purpose flour is so widely used (and a default whenever a recipe simply calls for flour) because it's a good middle ground between flours that are higher or lower in gluten.
Once you know the difference between cake flour and all-purpose flour, understanding when to use which flour becomes a bit easier. But the #1 rule is to follow the recipe. Use cake flour in recipes where you want an extra-light, extra-fluffy texture, like Angel Food Cake, Cream Cheese Pound Cake, or Buttermilk-Chocolate Cake. You can also use cake flour to bring a more tender crumb to other sweets, like Chocolate Crinkle Cookies.
If a recipe doesn't specify a certain type of flour, it's generally advisable to use all-purpose flour. All-purpose flour can be used for breads, muffins, cakes, and more.
Protein content isn't the only thing that's different about these flours. As Cooking Light points out, "All-purpose flour weighs about 4.5 ounces per cup while cake flour weights about 4 ounces per cup." (Remember, there is a right way to measure flour.)
Because of this discrepancy, you'll want to use a bit more cake flour to make an accurate substitution for all-purpose flour. Add an extra 2 tablespoons per cup of cake flour to equal the quantity in 1 cup of all-purpose flour.
If you're substituting all-purpose flour for cake flour, you'll want to reverse these ratios: Use 2 tablespoons less AP flour per cup of cake flour, and add 2 tablespoons of corn starch per cup.