Baking soda and baking powder: two necessary ingredients in any baker’s pantry and two very similar looking items that do function in similar ways as well. But knowing the difference is important.
What They Have in Common
Baked good recipes from quick bread to cake and cookies often call for a mere teaspoon of one or the other chemical leavener in your mixture, but you’ve probably wondered why you need to keep both in your pantry. After all, they both create gas, causing a chemical reaction which makes baked goods rise. Each contains sodium bicarbonate, an alkaline chemical that gives off carbon dioxide when mixed with an acid.
So what is the difference between baking soda and baking powder?
Baking Powder vs. Baking Soda
Baking soda consists purely of sodium bicarbonate, so recipes calling for it must include an acidic ingredient like lemon juice, vinegar, buttermilk, or brown sugar (the molasses in brown sugar is acidic) to activate it. Baking powder contains some baking soda, cornstarch to keep it from clumping together, and one or more acidic salts, which act as the activating/neutralizing agents for the bicarbonate.
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The two leavening agents work at different speeds. Baking soda produces gas immediately upon contact with liquid acid. Remember when you were a kid and you’d mix it with Coke to get a crazy foaming effect? Your dough or batter begins rising the minute you mix in the soda. Baking powder, on the other hand, creates a little gas when you first mix it in (that’s the baking soda working), and then more when the acidic salts have had a chance to fully dissolve, and yet a little more when your product is put in the oven.
That’s because the acidic salts most commonly used in baking powder need heat to work fully. The names of these acid salts are cream of tartar—also known as potassium bitartrate, a by-product of winemaking that has nothing to do with tartar sauce—and calcium aluminum phosphate. That’s why the vast majority of baking powders sold in grocery stores today are what’s known as double-acting baking powder: They’re rising once, then again.
When to Use Baking Soda and Baking Powder
So why use one over the other? Baking powder is often called for in recipes in which there is no acidic ingredient, as the powder contains its own acid component. And that built-in acid ensures that the soapy taste of unneutralized bicarbonate will not be present in what you’re making. Baking soda is often called for in recipes in which color is an issue, says baking expert Shirley Corriher, author of the books “CookWise” and “BakeWise.” Cookies that are more alkaline will brown better, Corriher explains. Dark chocolate cakes will be darker the more alkaline they are.
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But beware of confusing the two. If you use baking soda in a recipe that calls for baking powder, and there isn’t an acid among the ingredients, your product won’t rise. Even if there are acidic elements in your recipe, it may still not rise, because you made the batter too alkaline. (Eggs need the proper acidity to set, for instance.) If you switch out powder for soda, you may not get enough gas, because baking powder contains so much less bicarbonate per volume than soda.
Where Does Baking Soda Come From?
You may never have wondered, but this is probably the most interesting part of the story. Baking soda is mined from the earth. Most of the baking soda in North America comes from trona, a sodium bicarbonate–containing mineral whose largest deposit is underneath Green River, Wyoming. The trona is cleaned and milled to a powder, and you’ve got baking soda. In places without extensive trona deposits, like Europe, baking soda is made using the Solvay process, a reaction involving table salt and ammonia.
Another side note: Some people don’t like to use baking powder with aluminum because they believe it gives food a vaguely metallic taste, and because it has been suggested that there may be a link between aluminum consumption and Alzheimer’s disease. Studies have not proven this, however.
Is There a Baking Soda Substitute?
If you’re all out, in a pinch, you can use baking powder instead of baking soda—use a ratio of 3:1 (so 3 teapoons baking powder in place of 1 teaspoon baking soda), and omit or reduce the salt in your recipe.
How to Make Homemade Baking Powder
Want to make your own baking powder and ensure it doesn’t have any aluminum in it? It’s easy. Simply add two parts cream of tartar to one part each of baking soda and cornstarch.
Why Do Some Recipes Call for Both?
You’re apt to notice baking soda and baking powder in the ingredients for something that contains yogurt or another acidic ingredient (like our Buttermilk Blueberry Pancake recipe). Baking soda alone isn’t enough to leaven the batter, so baking powder comes in to provide additional lift and volume. Flavor and browning factor are other reasons to use both; read more on the Sally’s Baking Addiction blog.
Can They Go Bad?
Baking powder and baking soda can both go bad—not as in they’ll make you sick, but in that they’ll lose their potency. If you’ve ever had cookies fall flat, that could have been the culprit, so always check the expiration date. Here’s an easy way to test if your baking soda is still good:
If it’s not fit for baking, you can still use it to clean your kitchen and absorb odors in your fridge.
Baking powder generally has an even shorter shelf life (from six months to a year), but David Lebovitz offers this tip for testing whether it’s still good to bake with: “To test if baking powder is still active, spoon 1/2 teaspoon in a bowl and pour 1/4 cup (60 ml) of boiling water over it. Right away it should bubble up violently. If it does, it’s still good. If it doesn’t, discard it and open a new tin.”
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