Baking soda and baking powder are both considered to be leaveners however, they are chemically different.
Baking soda is also known as bicarbonate of soda OR sodium bicarbonate and it is considered to be a “base“. When a “base” is added to an “acid” is creates a reaction which in baking is what causes baked goods to rise. Common acids used in baking are buttermilk, lemon juice, cream of tartar or vinegar. It is important to use just the right amount of base and acid when baking, using too much baking soda will impart a soapy, metallic taste into your baked goods. Also note, baking soda is 3-4 times stronger than baking powder.
Baking powder is a mixture of baking soda, cream of tartar and sometimes cornstarch. Most of the baking powder that is found in stores will be labeled as “double-acting” which means that it will cause the leavening action twice. The first leavening occurs when the wet ingredients are mixed with the dry ingredients. The second leavening occurs when heat is introduced during the baking process. Since baking powder already has an acid (cream of tartar) built-in, it is not usually necessary to add any additional acid to the recipe.
Recipes that call for both baking soda and baking powder do so in order to create a balance of flavor, even browning, and in some recipes using the two together will give the baked goods a little extra “lift” when baking.
**TIP** – Periodically, take a minute to test the effectiveness of your baking soda and baking powder. To check baking powder, add 2 tsp powder to 1 cup of hot water and stir. If there is an immediate fizz, the baking powder is fine. To check baking soda, add 1 tsp of soda to 1/4 cup vinegar and stir. If there is an immediate reaction and fizz, the baking soda is fine.
GENERAL RULE OF THUMB
- Use 1/4 tsp of baking soda per 1 cup of flour
- Use 1 tsp of baking powder per 1 cup of flour