Make it Yourself...Eggs as leavening agents

Soft and Stiff beaten eggs, Beaten yolks, Jelly Roll

 Eggs serve as leavening agents in their ability to foam. Egg whites or egg yolks can each foam separately or together as a whole egg. Whisking egg white incorporates air and produces a foam - a relatively stable mass of bubbles. Whole eggs incorporate air less well, especially when beaten into a batter, but give a sponge cakes a light texture. Beaten eggs are a leavening agent as they incorporate air into the batter, which will expand in the oven and cause cakes and souffles to rise. 

If left to stand, egg white foam will gradually collapse, but when heated the foam becomes permanent, such as in a meringue. Some cakes, such as Angel Food Cake use beaten eggs as their only source of leavening, as do egg souffles.  

 Eggs, as well as flour, are the structural ingredients in baking. Eggs provide leavening; add color, texture, flavor and richness to the batter. 

 Over beating of egg whites can cause some problems in folding them into other ingredients and may collapse more easily.  They should just hold a soft or stiff peak which ever your recipe calls for.

Always fold them into other mixtures, not stirring them in as you want to keep as much air as possible in the beaten egg mixture. Under beating of course will cause you some problems also as they will not hold a structure as well. Really it isn’t as hard as this sounds, just use some common sense and you will be fine.