What's wrong with commercially prepared baking powder?
Most commercial baking powders use cornstarch to prevent caking. This is a problem if you are sensitive to corn. Luckily it is easy to make your own corn-free baking powder from scratch. Make up a big batch and store it in an airtight container. Use as you would store bought.
Corn-free Baking Powder:
1 part baking soda 2 parts cream of tartar 2 parts arrowroot powder
That's it. Mix it up.
This is a single acting baking powder, meaning that the chemical reaction occurs when the baking powder comes in contact with a liquid. For best results, mix the dry ingredients of your recipe first, mix the wet ingredients separately, then combine.
Cream of tartar is a derivative of the wine making process, it can be found in the spice section of most supermarkets. Arrowroot powder is the starch from the arrowroot plant, it can be found at natural food shops.