Not all types of flour are created equal. While batters and doughs made with cake flour and those made with all-purpose flour might appear indistinguishable to the naked eye, and also taste pretty much the same (although don’t eat either of ’em raw), they do have different effects on a baked good’s finished outcome.
While cake flour typically comes in a box and all-purpose flour comes in a bag, the biggest difference between these types of flour is the gluten protein content, which is 3%-5% higher in all-purpose flour compared to cake flour. Higher protein content yields stronger gluten bonds, making for overall firmer dough. Consider the difference in interior crumb structures between a loaf of sourdough bread and a moist vanilla cake. In a loaf of bread, that interior should be chewy, toothy, open, and firm. By contrast, tender cakes should have significantly smaller, tighter crumb structures, plush aeration, and crumble far more easily.
Determining which type of flour to use in a recipe will largely depend on the desired textural outcome. Using cake flour to make a batch of cookies, for instance, will yield a soft, crumbly texture, which could be a good fit for frosted sugar cookies. On the flip side, baking cookies with all-purpose flour will yield a firmer, chewy mouthfeel, which might be preferable for chocolate chip or peanut butter cookies.
What is cake flour?
Cake flour is made from soft wheat milled extra-fine. That fine mill increases the flour’s overall surface area, maximizing its potential for water absorption (hello moist cake!) and facilitating even, uniform dispersion of fats like butter and vegetable oil in the batter. Cake flour’s soft wheat has a naturally lower gluten content (roughly 5%-8%) and higher starch compared to all-purpose flour, all of which discourages gluten protein bond development. The result is a softer dough that crumbles more easily once baked. Cake flour creates more tender cakes than all-purpose flour, and it’s crucial for light, tight-crumb confections like angel food cake or Victoria sponge, and airy, fluffy biscuits.
While bakers around the world have leaned on flour as a staple ingredient for centuries, cake flour wasn’t invented until 1894 by Addison Igleheart, the brain behind Swans Down Cake Flour. The cake-transforming ability of the eponymously-named ingredient quickly gained popularity, and on its tenth birthday, cake flour won a prize at the 1904 World’s Fair.
What is all-purpose flour?
All-purpose flour is made from a blend of both hard and soft wheat. Hard wheat has higher gluten content than the soft wheat from which cake flour is exclusively made, giving all-purpose flour a mid-range gluten content of 10%-13%. This extra protein creates comparably tougher, chewier, denser, stickier doughs.
All-purpose flour’s gluten bonds are necessary for building firm, elastic loaves of bread. We combine it with whole-wheat flour (14% gluten content) to make this rustic “Lord of the Rings”-inspired lembas bread. But all-purpose flour is also our choice for making this soft, dessert-like strawberry vanilla bread and our brown-butter banana bread recipe, too. In short, all-purpose flour — as its Everyman name suggests — is more versatile for creating a wide range of baked goods, while cake flour is the best choice for specifically making plush tender cakes.
All-purpose flour is the right choice any time a firmer, breadier structure is the goal. It’s the key to chewy fudgy brownies, pound cake, and oatmeal raisin cookies with some structural firmness. All-purpose flour’s structural firmness also has utilitarian importance when it comes to lemon bars, carrying that luscious lemon curd, or pizza crusts (although you could also use OO flour in those), supporting heavy toppings.
How to substitute cake flour for all-purpose flour
Happily for home bakers, all-purpose flour can be substituted for cake flour in a pinch. All-purpose flour is more widely-available in grocery stores and often comes with a marginally lower price tag. A 32-ounce box of cake flour by Swans Down costs $4.29 on Amazon, while a five-pound bag of Gold Medal all-purpose flour runs for $3.98.
To substitute all-purpose flour for cake flour, replace two tablespoons of all-purpose flour with cornstarch for every cup of cake flour called for in the recipe. For thorough incorporation, pass your flour and cornstarch mix through a sifter. If you’re a stickler for accuracy, you can bring in even greater aeration by sifting your cornstarch-flour mixture four or five times, mimicking cake flour’s natural fluffiness.
On the flip side, to substitute cake flour for all-purpose flour, use one cup plus two tablespoons of cake flour per cup of all-purpose flour called for in the recipe. Although, it’s worth noting that all-purpose flour makes a better stand-in for cake flour recipes than the reverse. Cake flour cannot develop the same gluten bonds — and while a slightly firm German chocolate cake isn’t the end of the world, a falling-apart loaf of bread or brownies that don’t stick together are less ideal.
