Baking soda and baking powder may look and sound the same, but they certainly aren’t. They’re both leavening agents used to help baked goods rise, but interchanging them could lead to very different results—all because of science!
Whether you’re a beginner or a pastry pro, learning the difference between these two white powders can help you become a better baker and make your treats tastier than ever.
What is Baking Soda?
Baking soda, also known as sodium bicarbonate, is a white crystalline powder commonly used as a chemical leavening agent in baked goods.
It’s naturally alkaline or basic, which means it reacts with acids to create the carbon dioxide “bubbles” responsible for giving your cakes, cookies, and quick breads a lovely lift!
This is why most recipes that use baking soda also include acidic ingredients, like lemon juice, buttermilk, yogurt, cocoa powder, or molasses.
When baking soda becomes activated by an acid, the batter or dough rises and expands in the oven, resulting in a light and fluffy finished product.
Baking soda also enhances food flavor and gives your goodies that beautiful brown color! It may have a metallic taste, but it’s usually neutralized when used with an acid.
What is Baking Powder?
Like baking soda, baking powder is a leavening agent, too. The difference is it’s made up of a mixture of baking soda, an acidic ingredient like cream of tartar, and a thickener, like cornstarch.
Since it already contains an acid, baking powder only needs a liquid to activate and cause your dough or batter to rise. During storage, cornstarch acts as a moisture absorber that prevents the acid and base components of your baking powder from prematurely reacting.
Most store-bought baking powders are “double-acting.” This means the product first reacts and releases carbon dioxide when it touches a liquid, and again when exposed to heat in the oven.
Meanwhile, single-acting baking powder releases all of its carbon dioxide when dampened. They’re usually only used by food manufacturers since the extended reaction from double-acting baking powder is more favorable for regular household baking.
When to Use Baking Soda and Baking Powder
You’ll commonly find baking soda in recipes that feature a prominent acidic ingredient. Examples include snickerdoodles, which uses cream of tartar, Irish soda bread, which uses buttermilk, and gingersnap cookies, which uses molasses!
Aside from being used for its rising power in various baking recipes, baking soda is also a highly effective cleaning product! It can remove stubborn stains, grease, and dirt when scrubbed with a sponge, and also doubles as a deodorizer, leaving behind a fresh, clean fragrance.
Because baking powder is already a “complete” leavening agent, it’s often used in recipes where acid is not a main ingredient. It’s also used instead of yeast for baked goods where fermentation flavors are unnecessary or to speed up production, such as in quick breads.
Why Do Some Recipes Use Both?
Some pastry recipes call for a combination of baking soda and baking powder to ensure that your baked goods get the lift that they need. That way, you’ll end up with a finished product that’s as light, lofty, and fluffy as you want.
Using baking powder alongside baking soda also allows you to retain the flavor profile of your food. For instance, if you only use baking soda in making buttermilk biscuits, the soda will neutralize the acidic buttermilk, so you’ll lose the tanginess that makes the recipe special.
In this case, adding baking powder to the recipe means you can add less baking soda, thus preserving the signature tangy taste of your biscuits!
Baking soda is also a big help in the browning process. So, adding some baking soda to a batter with baking powder will help your baked goods achieve a nice golden brown color.
How to Test Baking Soda and Baking Powder for Freshness
Like most kitchen ingredients, baking soda and baking powder can lose their effectiveness over time. Once opened, the two leaveners can last from six months to one year, but there are a few tricks you can try to test their freshness, so you don’t end up with a flat cake.
For baking soda, add a teaspoon into a small bowl and pour in a tablespoon of vinegar or lemon juice. If it bubbles and fizzes like the volcano project you once did in school, it’s still fresh! But, if it doesn’t, it’s best to toss it in the trash.
To test baking powder for freshness, all you have to do is add ½ teaspoon to a bowl and pour ¼ cup of hot water on it. You’ll know that the powder is active if it bubbles vigorously.
Sarah is the founder of Baking Kneads, LLC, a blog sharing guides, tips, and recipes for those learning how to bake. Growing up as the daughter of a baker, she spent much of her childhood learning the basics in a local bakery.