While whole eggs, yolks and egg whites all supply practical benefits to baked goods, it is egg whites that achieve a lofty, stable foam for aeration or a leavening effect. In fact, egg whites, when whipped, can produce foam six to eight times greater in volume than the original liquid. These foams help aerate many different types of popular baked goods—including angel food cake, sponge cake, layer cakes, cookies, meringues and even hearth-baked breads and rolls.
Aeration is referred to as a critical function when formulating baked goods. It basically means that a gas, or air, is being introduced into the liquid batter. Beaten egg whites supply a highly effective1 leavening agent that helps incorporate air into the dough or batter.