A powdered compound used in baking as a leavening agent. It consists of sodium bicarbonate (baking soda) and a starch, such as cornstarch. Baking powder is added to doughs and batters, becoming activated when it is mixed with liquid and then continuing to react as it is heated. This type of powder is referred to as double acting Baking Powder, since it acts twice during the preparation process. During the initial mixing, the chemical reaction releases carbon dioxide gas causing the baked item to rise. Baking Powder is used in recipes that contain no other acidic ingredients, so that the addition of an acidic ingredient like Baking Powder, helps to create a balance in the chemical processes that occur during mixing and baking. When sufficient acid exists in the ingredients, then Baking Soda is typically used instead of Baking Powder.
As a means of testing the life of Baking Powder, place a teaspoon of the powder in 1 cup of warm water. If a bubbling action occurs, the powder is still active and can be used. If there is no action, then discard the Baking Powder. Baking Powder should be kept in an airtight container in a cool dry area away from any type of moisture or heat. Do not store Baking Powder in a refrigerator because it will tend to absorb moisture and eventually become inactive. Baking Powder can be stored for approximately 6 to 8 months before needing to be replaced.
As a substitute for Baking Powder, mix 1/4 teaspoon of baking soda with 1/2 teaspoon of cream of tartar.