Eggs, as well as flour, are the structural ingredients in baking. Eggs provide leavening; add color, texture, flavor and richness to the batter. They are very important in helping to bind all the other ingredients together. Beaten eggs are a leavening agent as they incorporate air into the batter, which will expand in the oven and cause the cake to rise. Some cakes use beaten eggs as their only source of leavening. Eggs are ... used as a thickener in custards and creams, and to glaze pastries and breads.