Blancs d’Oeufs et Meringues

Egg whites are composed of several proteins and, when the correct amount of air is properly beaten into them to create an egg-white foam, the proteins will stay soft, moist, and elastic. This is a very important aspect of a great many pastry items, such as cakes, soufflés, and mousses, where the foam gives the finished product its light, airy texture. When sugar is added to the egg foam, the mixture is called a meringue.

Once a cake prepared using an egg-white foam is put into the oven, the heat causes the air bubbles to expand, giving the baked cake its desired rise. The heat then cooks and sets (or coagulates) the proteins around the bubbles. If the egg-white foam is solely responsible for leavening the cake, it is said that the cake rises due to mechanical leavening, i.e., by means of the air bubbles created during the action of beating or whisking egg whites. (There are some circumstances in which a cake is leavened by both mechanical and chemical action, an egg foam and a chemical leavener.) A meringue performs this same leavening action in mousses and Chiboust creams, often with the assistance of gelatin, to set the product if no baking is involved.