How long does baking powder last? The shelf life of baking powder depends on a variety of factors, such as the best by date and how it is stored. Baking powder is a leavening agent that releases carbon dioxide when moistened. This produces air bubbles in baked goods which cause them to expand and become lighter while baking. Thus it is a key ingredient to making airy breads and cakes.

Baking powder is a mixture of baking soda, cream of tartar and cornstarch and comes in three types: fast-acting, slow-acting and double-acting. Double acting is the most common which reacts twice, once when liquid is added to the mixture and then again when heat is introduced.

So, does baking powder expire or does baking powder go bad? When properly stored, the shelf life of baking power is actually Indefinite, but the useful shelf life past its best by date is approximately ...