Cooking can be a great arena in which to experiment. Sure, there are plenty of recipes, but you don’t always have to stick to the guidelines—a pinch of this, a splash of that, a little taste test, and there's dinner. Baking, on the other hand, is a bit more strict. It requires accuracy, precise measurements, and science! Descriptions and ingredients are given for a reason, and only when following them will you achieve the specific result. While there is some room to tinker, the best bet is usually to stay on the path of a great recipe that has proven to work.
So if you want to make a cake with a recipe that calls for cake flour, it stands to reason that that’s the flour you should use. Unfortunately, this is not always the most opportune. You probably have a bag of all-purpose flour floating around in your cupboard, but cake flour? Maybe not.
What's the difference between AP flour and cake flour (and, for that matter, bread flour) anyway?
While wheat flours—including all-purpose flour, bread flour, and cake flour—vary based on factors like where and under what conditions the wheat was grown, the biggest difference between the flours that home bakers need to think about is the protein content. The amount of protein in each flour will ultimately determine the gluten (the stuff that helps baked goods rise and gives them texture, structure, and shape) it's capable of developing once combined with liquid and mixed or kneaded. Because of this, flours with a high amount of protein are used to make sturdy, yeasted products, while flours with a lower protein level are better suited for baked goods that have a tender texture and finer crumb (things like pastries, cake, and cookies).
Bread flour is often made from something called “patent flour,” milled from a "hard," or high-protein, wheat, that distinguishes it as a “strong” flour. Creamy white in color, it has a protein level between 11 and 13 percent and is a bit coarse when you rub it between your fingers. If you were to squeeze some into a lump in your hand, it would fall apart immediately.
Cake flour, on the other hand, has a protein level around 8 percent, making it prime for light and airy cakes. It's made from "soft," or low-protein, wheat and is pure white and smooth to the touch. A handful of this squeezed into a lump will keep it’s shape for a bit.
All-purpose flour is a blend formulated to be a floury middle-ground, having protein levels around 11 or 11.5 percent. This allows it to be interchangeable, working well in a variety of baked goods and pastries—and that's why it is the most popular bag to have around. This also means that you can manipulate AP flour, Macgyvering it into something similar to cake flour at home!
How to transform AP flour to cake flour:
Using your all-purpose flour, measure out the amount of flour your recipes calls for. For the sake of explanation, let’s just say it’s three cups.
Next, remove two tablespoons of flour for each cup: So for those three cups of flour, you would remove six tablespoons. Replace the missing flour with an equal amount of cornstarch (this means six tablespoons of cornstarch are going in your flour) and whisk it together.
Now sift it like you mean it!
And voila! You’ve got cake flour (sort of).
This works because cornstarch is acting as a neutral, protein-free element. By taking out some of that AP flour and replacing it with cornstarch, you are cutting out some of the protein-containing grains while still maintaining the same measure of volume. All that hardcore sifting helps, too: Not only does this integrate everything, it also aerates your flour mixture, ultimately helping you create an even more delicate crumb (i.e. an even more dreamy cake).
Now, go bake!
What's your best baking trick? Let us know in the comments!