Whole wheat pastry flour has been milled from a soft wheat bran, with a fine texture. The purpose of using a pastry-type flour is ideally to create lighter, fluffier baked goods. Using whole wheat is far healthier than using white flour, which has been stripped of many essential nutrients. Wheat maintains many of the nutrient-dense fibres that are better suited for optimal health.
If you're looking to substitute wheat because of allergy issues, you might be able to use spelt flour. Spelt is similar to wheat; it's a subspecies of wheat and contains gluten, so when baking with it, it carries properties similar to those of wheat. For some wheat allergy suffers, though, spelt is suitable for consumption. If you suffer from coeliac disease, however, eating spelt is not advisable.
Baking without Wheat
Attempting to bake with alternative flours can be tricky -- primarily because the quality of the wheat, which is responsible for making our favourite baked goods so desirable, is missing. If you're not careful, instead of being light and airy, your pastries might turn out dense and even gritty. Usually, combining alternative flours is optimal, but it takes time to determine which ones function best together -- and success will ultimately come only from trial and error. The flour combination that makes a good brownie might not work for bread baking and vice versa. If you're not up for experimenting, you can always purchase gluten-free baking flour in pre-mixed packages.
The key ingredient lacking in pastry dough when using alternative flours is gluten, although some alternative flours contain gluten in small amounts. Gluten acts as a binding agent, holding pastry dough together. Without it, something else needs to be added to promote the familiar, and desired, consistency. For every cup of any gluten-free flour you use, add 1 tsp of either xanthan gum, guar gum or pre-gel starch. Any of these ingredients can be purchased at a health food store, and supermarkets increasingly carry them as gluten-free baking becomes more mainstream.
Rice flour is a favourable substitute for wheat flour. It's been used by bakers the world over in making gluten-free baked goods. In health food stores, it's not uncommon to find doughnuts, Swiss rolls and various breads made from rice flour. Other common alternatives include: soy flour, oat flour, quinoa, kamut, amaranth, millet, barley and many more.