Baking soda and baking powder are both leavening agents, which are substances used to help baked goods rise. Baking powder contains baking soda, along with other ingredients. Experienced and amateur bakers alike often confuse them due to their similar names and appearances.
Baking soda is a leavening agent used in baked goods like cakes, muffins, and cookies. Formally known as sodium bicarbonate, it’s a white crystalline powder that is naturally alkaline, or basic.
Baking soda becomes activated when it’s combined with both an acidic ingredient and a liquid. Upon activation, carbon dioxide is produced, which allows baked goods to rise and become light and fluffy. This is why recipes that include baking soda will also list an acidic ingredient, such as lemon juice or buttermilk.
Baking powder is a complete leavening agent, meaning it contains both the base (sodium bicarbonate) and acid needed for the product to rise. Cornstarch is also typically found in baking powder. It’s added as a buffer to prevent the acid and base from activating during storage.
The acid in baking powder reacts with sodium bicarbonate and releases carbon dioxide once it’s combined with a liquid. Single- and double-acting baking powders are available, though single-acting varieties are typically only used by food manufacturers and not usually available for household use.
When a recipe calls for baking powder, it’s most likely referring to the double-acting kind. This means the powder creates two separate reactions: initially, when combined with liquid at room temperature, and secondly, once the mixture is heated. For many recipes, an extended reaction is favorable, so the leavening, or rising, doesn’t happen all at once.
Baking soda is used in recipes that also include an acidic ingredient, such as cream of tartar, buttermilk, or citrus juice. Conversely, baking powder is typically used when the recipe doesn’t feature an acidic ingredient, as the powder already includes the acid needed to produce carbon dioxide.