cups cake flour or all purpose flour plus cornstarch (see my note to make cake flour)
To achieve the soft, fluffy texture characteristic of professional cakes and Asian steamed buns (Siopao), cake flour is preferred for its lower protein content. If you only have all-purpose flour on hand, you can easily create a substitute by blending it with cornstarch to inhibit gluten development.
Homemade Cake Flour Substitute
For every 1 cup of cake flour required in a recipe, use the following ratio:
- 2 tablespoons cornstarch
- All-purpose flour (enough to fill the remainder of the cup)
Instructions
1
Measure the cornstarch
Start with the starch
Place 2 tablespoons of cornstarch into a dry 1-cup measuring tool.
2
Add the flour
Level off the top
Spoon all-purpose flour into the cup until it is overflowing, then use the back of a knife to level it off.
3
Sift repeatedly
Aeration is key
Sift the mixture into a bowl. Repeat the sifting process 3 to 5 times. This mimics the fine, airy texture of commercial cake flour and ensures the cornstarch is perfectly distributed.
Why the Substitution Works
All-purpose flour typically contains 10-12% protein, whereas cake flour is closer to 7-8%. By replacing a portion of the flour with cornstarch—which contains no protein—you effectively lower the overall protein percentage of your blend. This results in a “tender crumb” and prevents the dough from becoming overly chewy or tough.
