In the beating of eggs, it should be remembered that for some purposes, as in making some kinds of sponge cake, they are beaten until nearly frothy. It is well also to observe that egg whites should always be beaten in the same direction and that the same motion should be continued throughout the beating, for a change of direction or motion always causes a loss of air. A final precaution to take is never to allow egg whites to stand after are beaten. If this is done, the leavening power of the eggs is reduced, because the air soon escapes from beaten eggs and leaves underneath them a clear liquid that can never be beaten up. For instance, eggs that are to be used for boiled icing should not be beaten until the sirup has finished boiling. However, eggs that have been separated but not beaten may stand for a couple of hours, provided they are covered and kept in a cool place. As has been previously stated, the substance in eggs that requires special care in the cooking process is the protein, which occurs in this food in the form of albumen. Because of this, certain points concerning the treatment that the albumen requires should be kept in mind. In a raw egg, the albumen occurs in a semiliquid form, but it coagulates at a lower temperature than does the yolk, which contains a high percentage of fat. After coagulation, the consistency of the two parts is very different. The white is elastic and more or less tough, while the yolk, upon being thoroughly cooked, becomes powdery, or mealy, and breaks up into minute particles. The egg white begins to coagulate at 134 degrees Fahrenheit, and it becomes white and jellylike at 160 degrees. Bringing an egg to such a temperature produces a more desirable result than cooking it at a high temperature–boiling point, for instance–because the albumen, instead of becoming tough, as it does at a high temperature, acquires a soft, tender consistenc that exists throughout the entire egg. An egg cooked in this way is more digestible and appetizing than one that is boiled until it becomes hard and tough.
The low temperature at which eggs will cook in the shell applies also to eggs when they are combined with other foods. Sometimes, however, a mixture in which eggs are one of the ingredients must be cooked at a high temperature because the materials mixed with them require it. This difficulty can be overcome when eggs are combined with starchy foods, such as corn starch, rice, and tapioca, that require long cooking. In such a case, all the ingredients except the eggs may be cooked the length of time they require, after which the eggs may be added so that they will cook just long enough to become coagulated. Longer cooking is liable to spoil the texture. Often the starchy mixture retains sufficient heat to set the eggs without further cooking after they are added.
A very nutritious way in which to prepare eggs when they are to be used for a dessert is to combine them with milk to form a custard, which, after being sweetened and flavored, is baked. The proportion that has been accepted as ideal to produce a dessert of the right thickness is one egg to each cupful of milk; however, an entire egg is not always required, as one yolk is often sufficient to thicken 1 cupful of milk. Care should be taken in the cooking of such custards, for if they are cooked too long or at too high a temperature they will curdle and whey; whereas, a properly cooked custard–that is, one cooked slowly at a low temperature and for the required length of time–will have a smooth, jellylike consistency. A slight variation in a dish of this kind is secured by reducing the number of eggs and thickening it with corn starch or some other starchy material. While such a mixture is not a true custard, it makes an excellent dessert.
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.
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. The manner of serving eggs depends, of course, on the way in which they are cooked. One point, however, that should never be overlooked, so far as eggs that are to be served hot is concerned, is that they should be served immediately upon being prepared, so that they will not have an opportunity to become cool before being eaten. This applies particularly to any spongy mixture, such as puff omelet and soufflé, as these dishes shrink upon standing and become less appetizing in both appearance and texture. Several ways of serving soft-cooked eggs are in practice, but probably the most satisfactory way is to serve them in egg cups. In case cups are used, they should be heated before being placed on the table, as the heat that they retain helps to keep the eggs warm. The eggs may be removed from the shell into the cup and eaten from the cup, or the unbroken egg may be placed point downwards in the small end of the cup, a small piece broken from the broad end of the shell, and the egg then eaten from the shell through the opening made in it. If egg cups are not available, the eggs may be removed from the shell and served in small dessert dishes, which also should be heated. Many egg dishes are made more attractive and appetizing by means of a garnish of some kind. Small strips or triangular pieces of toast, sprays of parsley, celery leaves, lettuce, and strips of pimiento are very satisfactory for this purpose. If no other garnish is desired, just a sprinkling of paprika adds a touch of color.
In connection with the serving of eggs it will be well to note that they have a tendency to adhere to china and to discolor silver. Therefore, in the washing of china and the cleaning of silver that have been used in the serving of raw or slightly cooked eggs, much care should be exercised. Dishes in which eggs of this kind have been served should first be washed in cool water in order to remove all the egg, and then they should be thoroughly washed in hot water. If the hot water is applied first, the heat will cause the egg to coagulate and cling to the dishes. Silver that comes in contact with eggs tarnishes or becomes discolored through the action of the sulphur that is found in them, just as it does when it is exposed to the air. Dark spots that appear on silver from this source may be removed by means of a good silver cleaner.