Agents that are used to lighten the texture and increase the volume of baked goods such as breads, cakes and cookies. Baking powder, baking soda and yeast are the most common leaveners used today. When mixed with a liquid they form carbon dioxide gas bubbles, which cause a batter or dough to rise during (and sometimes before) the baking process. The air beaten into egg whites leavens some foods, such as angle food cake and sponge cake. When heated, the egg whites cook and set, trapping the air inside and creating a light, airy cake.