Substitute for Pastry Flour from Limited Traditional and Alternative Flours

Question

I have a recipe for sponge cake that calls for either all white pastry flour or an equal mix with whole wheat pastry flour. Unfortunately, the only pastry flour I have is whole wheat. The recipe specifically warns against All-Purpose, which it claims will dry the cake out. These are the flours I have...is there any hope?

• Whole Wheat Pastry Flour
• Unbleached White Whole Wheat Flour
• Unbleached White Flour
• Whole Wheat Flour
• Garbanzo Bean Flour
• Tapioca Flour
• Spelt Flour
• Buckwheat Flour

I also have traditional powders like xantham gum, baking soda, cornstarch, etc.

About.Com suggests "two tablespoons corn starch, combined with enough all-purpose flour to make a cup," but warns that the extra protein content will increase toughness.

Thank you!

Answer 1

I don't know why About.com warns that "additional protein will increase toughness" when the whole purpose of adding corn starch is to reduce the protein.

All purpose flour should have around 10% protein and 90% starch. Pastry flour has 8% protein and 92% starch. Cornstarch has 0% protein. You only have to mix cornstarch and all-purpose flour in the mathematically correct ratio to get a mixture which behaves like pastry flour in terms of protein toughening.

The numbers above are rounded, but then, different manufacturers will produce flours with different percentage of proteins, and some wheat proteins also get tougher than others depending on the cultivar, and recipes still work with that kind of tolerance. So I use them and mix 80 g AP flour and 20 g cornstarch for every 100 g pastry flour I need, which results in a flour mixture with roughly 8% protein content. I use it primarily for flaky crusts, and it works quite well there.

Answer 2

You can sift the whole flour to make it white flour.

Originally, millers used stones to grind the grains. The whole grain was completely ground, and all of its parts were mixed in the process. Wealthier people could sift the flour to discard the husks. Poor people ate whole flour bread.

Nowadays, flour is gotten from roller mills, where first the husk is removed, then the germ, and then the endosperm is ground. When you get whole flour (unless the miller says it's stone milled), they've put together the outer part and the endosperm. You can sift it to separate them.

So, in both cases, sifting the whole wheat pastry flour will make you get white pastry flour.