Make sure you use unbleached flour from a trust source (not some company who claims their flour is organic and unbleached.)
"Measure out 1 cup of all-purpose flour. Remove 2 tablespoons of all-purpose flour and place it back in your flour canister. Replace the removed all-purpose flour with 2 tablespoons of cornstarch.
Sift flour 5 times. Yes… 5 times. Sifting the flour and cornstarch together will help thoroughly combine the mixture and help to lighten and aerate the flour.
By replacing a bit of the all-purpose flour with cornstarch, we’re removing some of the gluten and replacing it with a tenderizing element. But cornstarch is so neutral, how is it a cake tender? Well, cornstarch works alongside other cake ingredients (like sugar, for example) to inhibit gluten development. It’s ingredients like sugar and cornstarch that compete with the flour for liquid absorption (think: eggs and buttermilk) in a recipe. If flour gets to gobble up all of the liquid in a recipe and is worked in a mixer (like we work cake batter), it’s gluten development will be off the charts… and you’ll basically have a baguette. Cornstarch (and sugar) makes the flour share liquid, easing the gluten development and creative beautifully tender cake texture.
King Arthur Flour makes my favorite store-bought cake flour. I love it because it’s an unbleached cake flour (pretty rare because cake flours are usually bleached), has no weird chemicals, and has a slightly higher protein content that helps make consistently great cakes.
If you’re like me and want to read majorly nerdy textbooks about food, Understanding Food: Principles and Preparations is a massive reference book about everything from food service to food science. It’s a splurge. The used book is the way to go.
See entire article @ Joy The Baker