EGGS AND THEIR VALUE AS FOOD. 13 
When beaten or whipped, eggs, and particularly egg whites, in- 
close air bubbles, many more being inclosed by fresh eggs than by 
packed or old eggs. When such beaten yolks and whites are added 
to batters or doughs the air bubbles are distributed throughout the 
mass, and when the dough is cooked the inclosed air expands and the 
walls of the air bubbles become firm, with the result that the porous 
structure is retained. Sponge cake and angel cake are familiar 
examples of foods made light with eggs. It is interesting to note 
that recipes for cakes and similar dishes to-day commonly call for 
fewer eggs than those of a generation or two ago. The reason is 
that, owing to the quite general use of baking powder, the house- 
keeper is not so often compelled to depend upon eggs to make her 
cakes light and need use only enough to give the desired flavor, color, 
and texture. In considering the uses of eggs as an ingredient of 
cakes and other dishes, it should be noted that they add materially 
to the nutritive value of the dish as well as to its quality and 
appearance. 
Besides their uses in foods of various sorts, eggs are often em- 
ployed as a garnish. Hard-boiled eggs, for instance, cut into dif- 
ferent shapes, are a common garnish for cooked greens or for salad; 
or, instead of being cut or chopped, the yolk may be put separately 
through a ricer. 
White of egg is employed for icings, meringues, and confectionery, 
particularly various sorts of cream candy, and for clarifying liquids 
(see p. 14). 
Since eggs are especially rich in protein, combining them with 
flour, starch, and sugar (typical carbohydrate-yielding foods) and 
butter and cream, which are rich in fat, is perhaps an unconscious 
effort to prepare a food which shall more nearly meet the require- 
ments of the body than any one of the ingredients alone. When 
eggs, meat, fish, cheese, or similar foods rich in protein are eaten, 
such other foods as bread, butter, potatoes, etc., are usually served at 
the same time, the object being, even if the fact is not realized, to 
combine the different classes of nutrients into a suitable diet. The 
wisdom of such combination, as well as of other generally accepted 
food habits, was proved long ago by practical experience. The reason 
has been more slowly learned. 
The total number of methods of serving and preparing eggs is 
very large, but in nearly every case each is only a more or less elab- 
orate modification of one of a few simple ways of cooking. Thus, an 
egg in the shell is cooked by immersion in hot or boiling water or is 
less commonly roasted. An egg removed from the shell may be 
cooked in hot water or in hot fat. In the latter case it may or may 
not be beaten or stirred. Combined with other materials to form 
