Baking powder is a leavening agent used in baking to help baked goods rise by producing carbon dioxide gas when exposed to moisture and heat. It is a dry chemical mixture composed of an acid (usually cream of tartar) and an alkali (usually baking soda or sodium bicarbonate), along with a starch or cornstarch as a filler.
Baking powder is designed to be stable and has a relatively long shelf life when stored properly. It does not require refrigeration because it does not break down significantly during cooking or in storage under normal conditions. The reason for this stability lies in its dry and inert nature.
The breakdown of baking powder occurs when it is exposed to moisture or liquid, as this activates the chemical reaction between the acid and alkali components. Once the reaction is activated, carbon dioxide gas is produced, causing the dough or batter to rise. However, this reaction doesn't happen significantly during storage because the dry powder remains relatively inactive until mixed with wet ingredients during the baking process.
To maintain the quality and effectiveness of baking powder, it is essential to store it in a cool, dry place, away from moisture and humidity. If it absorbs moisture from the air, it can lose its potency and may not work as well during baking. As long as you store baking powder properly and ensure it remains dry, it will stay stable and usable for an extended period without the need for refrigeration.