Leaveners

To leaven is to raise, or to make lighter. There are several ways to accomplish this in baking: with yeasts (also known as organic leaveners), with chemical agents such as baking powder or baking soda, or with steam (mechanical leavening). Each method is best suited to specific applications and produces very different results. The different leavening methods may be used alone or in conjunction with one another (as in croissants, for example) to yield different effects.