5.2.3: Physical Leaveners
Leavening agents play an integral role in the development of flour mixtures into final baked products. Leaveners directly aid in the process of rise and give products their distinct shape and flavor. Leaveners can be physical, biological, or chemical and this section discusses physical leaveners.
Physical Leavening Agents
There are two types of physical leavening agents; air and steam.
Air
Air is regularly incorporated into flour mixtures during several preparation steps such as mixing, stirring, creaming fat and sugar, sifting dry ingredients, and whipping. Air becomes trapped in between protein matrixes aiding in the final lift (or rise) in the baked product.
Steam
Water that is incorporated into the flour mixtures will produce steam when heated or cooked. Steam expands to many times its original volume pushing out on the gluten or other protein structures as bread or other flour mixture bakes. Steam acts as the primary leavening agent in popovers, pie crusts, and pastries.