Anyone who’s done any from scratch baking is familiar with baking soda and baking powder. But what’s the difference and are they interchangeable? As odorless white powders they certainly seem similar, but baking soda and baking powder are indeed two distinct leavening agents.
Baking soda is sodium bicarbonate and when combined with an acidic ingredient (buttermilk, lemon juice, etc.), it creates carbon dioxide gas, which expands in the heat of the oven and helps cookies, cakes, and other baked goods rise. The acid also neutralizes baking soda’s by-product, sodium carbonate, which happens to have a rather unpleasant metallic flavor. One very important thing to take away from all this is that you need to be careful with substitutions. For instance, in a recipe calling for baking soda and buttermilk, you can’t just use regular milk and get the same results (you’ll need to add an acid like lemon juice or vinegar).
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Baking powder is a mixture of baking soda, an acid, and cornstarch. In other words, that essential neutralizing acid is built in, so there’s no need to include an additional acidic ingredient in the recipe. If you’re experimenting and decide to add an acidic ingredient to a baking powder recipe, you’ll need to add baking soda to neutralize the acid. Baking soda is about 4 times as powerful as baking powder so using 1/4 teaspoon baking soda for every teaspoon baking powder is a good estimate.
As you’ve probably noticed, some recipes contain both baking soda and baking powder. In this case the baking powder is doing most the actual leavening, while the baking soda is there to neutralize the acid in the recipe as well as contribute to the rise.
Here are a few more points to keep in mind:
Always read recipes carefully to make sure you use the correct chemical leavening agent or the right amount of each one when they’re both included. Even without all the acid issues, baking soda is significantly stronger than baking powder so you can’t just swap one for the other.
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If you’re out of baking powder but do have baking soda and cream of tartar, you can make your own homemade baking powder.
Cocoa powder complicates things. Natural cocoa powder is acidic so it’s used with baking soda, while Dutch process cocoa powder has been alkalized to remove the acid, and therefore goes with baking powder. It’s all yet another reason to read recipes and labels carefully.
Recipes typically call for whisking or sifting together the dry ingredients. Sifting is a bit of a hassle and not always completely necessary, but it is important to at least whisk dry ingredients together as it helps distribute either or both chemical leavening agents, and that makes for even rising.
(Photo: Sara Bonisteel)