air cells [air-sells] noun
Also called air bubbles. Air cells are pockets of air in breads and cakes that create loft and desirable texture.
In yeast breads, it is the yeast that produces CO2 gas, which creates air cells. When you cut into a loaf of French bread, for example, you can see the varied sizes of holes that create the bread’s porous texture; the holes might remind you of the way Swiss cheese looks. In other baked goods such as cakes and quick breads, chemical leaveners like baking soda and baking powder produce the air bubbles. If yeast is killed through mishandling, or if your chemical leaveners are old, far less or no CO2 at all will be produced and your baked goods will be dense and flat.