44. In the cooking of mixtures containing eggs, no utensil proves quite so satisfactory as the double boiler, which has already been explained and illustrated. In fact, it is almost impossible to cook an egg mixture directly over the flame on account of the difficulty encountered in preventing the eggs from curdling. The low temperature at which cooking is possible in the double boiler makes it a comparatively simple matter to bring a mixture to the proper consistency without the formation of curds. Still, a certain amount of precaution must be taken even with a double boiler. If the degree of heat that is reached in this utensil is applied too long, the result will be no more satisfactory than when mixtures are exposed directly to the heat and cooked at a high temperature. While every effort should be made to cook mixtures containing eggs, such as custards or mayonnaise, so as to prevent curds from forming, occasionally they will form in spite of all that can be done. However, it is sometimes possible to remedy the matter by placing the vessel at once in cold water and beating the mixture rapidly with a Dover egg beater until the curds disappear. The cold water cools the mixture and prevents the formation of more curds, and the beating breaks up those which have already formed, provided they are not too hard.
45. In addition to the uses already mentioned, eggs have numerous other uses in cooking with which the housewife should be familiar. For instance, slightly beaten egg is used to a great extent to make crumbs or meal adhere to the surface of croquettes, meat, oysters, etc. that are to be sautéd or fried in deep fat, a coating of this kind preventing the food from becoming soaked with grease. In addition, egg is used to stick flour together for certain kinds of dough, such as noodles. Then, again, it is much used to puff up mixtures and produce a hollow space in them, as in popovers and cream puffs. While such mixtures do not require beating, spongy mixtures, such as omelets and sponge cakes, do. In these, eggs are an important factor, and they must be thoroughly beaten in order to incorporate the air in small bubbles and thus produce the desired texture.