What's the difference between baking soda and baking powder?
Have you ever stared into your pantry and thought, What the heck is the difference between baking soda and powder? Or looked at a recipe and had to double- or triple-check that you're using the right one? The two seem—and even sound—the same, and they do actually have a lot in common. But the little things that differentiate the two are so enormously important, confusing them can mean the difference between baked goods you want to eat and baked goods you wouldn't touch with a ten-foot pole.
We some digging to find out just what the difference between baking soda and baking powder is and why you absolutely never want to mix them up.
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Both baking soda and baking powder are used to make baked goods light and fluffy.
If you've ever ended up with a rock-hard platter of brownies, it probably had something to do with how much baking soda or baking powder you did (or didn't) use.
Each of these powders contain the same key ingredient: sodium bicarbonate. When sodium bicarbonate is combined with acid and water, a chemical reaction takes place that creates the gas carbon dioxide, Kelila Jaffe, a chef and the food-program coordinator at New York University Steinhardt tells SELF. This process is called leavening, and it's what keeps your cupcakes moist and fluffy instead of hard like hockey pucks.
Baking soda is pure sodium bicarbonate, Jaffe explains. Since sodium bicarbonate needs to interact with an acid to create that carbon-dioxide reaction, she says that you'll usually want to use it in a recipe that already calls for acidic ingredients—like lemon juice, buttermilk, or even yogurt—to ensure you're creating that reaction.
There are additional ingredients in baking powder—not just sodium bicarbonate. "Baking powder contains its own acid, usually in the form of cream of tartar," says Jaffe. Because it has its own source of acid, it can create carbon dioxide all by itself. So you can use it in recipes that don't have an acidic ingredient and still get that leavening effect.
Baking powder also contains an anti-caking agent that keeps the sodium bicarbonate and acid from sticking together. Jaffe says that usually the anti-caking agent is cornstarch, but it can vary from brand to brand. Certain brands will use anti-caking agents that contain gluten, so if gluten is something you're trying to avoid, be on the lookout for brands marketed as gluten free and double-check the ingredients label to be extra safe.
Now that you know the difference between the two, don't start using them willy-nilly.
"You want to be careful about the amount you use in baking," says Jaffe. "If you use too much of either baking powder or soda and not enough acid, you'll get something with a bitter, soapy taste."
Most recipes call for less baking soda than baking powder because baking soda is pure sodium bicarbonate and therefore super concentrated. If you're attempting to create your own recipe, Jaffe says the general ratio for baking soda is about ¼ teaspoon per cup of flour, and for baking powder it's a bit more—1 teaspoon per 1 cup of flour.
Wait, but what about recipes that call for both baking powder and soda?
Jaffe says that highly acidic recipes (like buttermilk biscuits or lemon cupcakes) are the ones that usually call for both baking powder and baking soda because they need more sodium bicarbonate to properly interact with the larger amount of acid. Otherwise, they might not create that leavening effect. Buttermilk biscuits are one example she mentions: "Because buttermilk has so much acid, you want the biscuit to be nice and fluffy, and baking powder by itself isn't going to provide enough gas to create that texture."