Baking powder, like yeast, is responsible for the rise in batters and doughs. It is a combination of baking soda (alkaline) and cream of tartar (acid) with cornstarch added for bulk and to prevent moisture in storage. When liquid is folded into dry ingredients, air bubbles begin to form during mixing or kneading. The baking powder mix creates a chemical reaction, carbon dioxide is released, and the bubbles expand.
Double-acting powder is the most common and causes a batter to rise twice. It contains two acidic ingredients, usually cream of tartar and S.A.S. (sodium aluminum sulfate/alum). The first action begins when liquid is added; the second occurs with heat. This is ideal as many products “rest” before going into the oven.
Single-acting baking powder (homemade) reacts only once, when mixed with liquid. Use only if planning to bake as soon as the ingredients are mixed.
Aluminum-free powders are available, which do not leave a taste in lightly-flavored baked goods. Low-sodium products are also marketed.
Kept cool, it will last up to twelve months.
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