Baking powder is a white, dry chemical, similar in texture to starch, used in batters and doughs for making breads, pancakes, waffles, cakes and similar. Using baking powder in a recipe causes a rising effect on the final result. The main ingredients of baking powder are
baking soda and one or two types of acids.
There are two types of baking powder available, the single acting baking powder and the double acting baking powder.
Single acting baking powder contains one type of acid that reacts
at low temperatures, thus, giving a rise as soon as the dough or batter
is prepared.
Double acting baking powder contains two types of acids, one which reacts at low temperatures (giving an immediate rise when the dough or batter is prepared) and one that reacts at high temperatures, producing further rising during the baking process.
When using single acting baking powder in a recipe, you must bake immediately after mixing, otherwise the rising effect will fail.