When a recipe calls for baking soda it will also call for some type of acid like buttermilk, brown sugar, yogurt, lemon juice, vinegar, cream of tartar, molasses, applesauce, natural cocoa powder or honey.
You need this additional ingredient in the recipe to react with the baking soda, which in turn creates carbon dioxide and allows your baked good to rise. This is called a leavening agent. Baking soda is 3-4 times stronger than baking powder. Do not over use this ingredient. Too much baking soda means there will be leftover baking soda in the recipe. This will create a metallic taste in the baked good.
Rule of thumb: 1/4 teaspoon of baking soda per 1 cup of flour in a recipe is usually sufficient.
Baking powder contains baking soda. Baking powder is made of a mixture of baking soda, cream of tartar, and on occasion cornstarch. Most baking powder sold is double acting.
The first leavening occurs when baking powder gets wet, for example when you combine the dry and wet ingredients in the recipe.
The second leavening occurs when the baking powder is heated in the oven.
Rule of thumb: Use 1 teaspoon of baking powder per 1 cup of flour in a recipe.
Recipes that call for both baking powder and baking soda contain some sort of acid (yogurt, brown sugar, etc), however the carbon dioxide created from the acid and baking soda is not enough to leaven the volume of batter in the recipe.
That’s why baking powder is used as well– to add necessary lift. When you need more leavening than you have acid available in the recipe. This keeps it balanced.
Another reason to use both baking powder and baking soda is because they affect both browning and flavor Baking powder and baking soda, both can settle down in their containers over time. It’s recommended to shake it up or give it a stir, then use a measuring spoon, to lightly scoop it out of the container. Use a knife (or the container if it has a leveler) to level it off.