Baking powder is a dry chemical leavening agent.
- It is used to increase the volume and lighten the texture of baked goods.
- It works by releasing carbon dioxide gas (CO2) into a batter or dough through an acid-base reaction, causing bubbles in the wet mixture to expand and thus leavening the mixture.
- Baking powder has different ingredients that create CO2 gas at different stages of the baking process.
- Stage 1: All baking powders contain sodium bicarbonate (just like baking soda). But baking powder also contains two acids. One of these acids is called monocalcium phosphate. Monocalcium phosphate doesn’t react with the sodium bicarbonate while it’s dry. But as soon as the baking powder is stirred into a wet dough or batter, the two ingredients begin to react, releasing bubbles of CO2 and causing chemical leavening.
- Stage 2: But to extend the chemical leavening process, it also contains a second acid, either sodium acid pyrophosphate or sodium aluminum sulfate. Neither of these acids react with sodium bicarbonate until they are both: A) wet (i.e., stirred into the batter) and B) hot.
- This means that the batter rises for a longer period of time, making lots of bubbles (and a fluffier cake, muffin etc.).
Image: Lou Sander