Arrowroot powder, potato starch (not flour), tapioca flour. These starchy flours mimic gluten’s binding properties. They also lighten the heaviness and distinct flavors of whole-grain GF flours. I use Bob’s Red Mill products, located in the baking section.

Guar gum or xanthan gum. Gums, used in small quantities (generally 1 teaspoon per cup of flour), help hold shape and eliminate crumbliness. Also sold in the baking section.