38. SEPARATING OF EGGS.--Frequently recipes require that the yolks and whites of eggs be beaten separately before being added to the other ingredients. When this is the case, care must be exercised in taking the egg from the shell. The method by which this is most easily accomplished is illustrated in Fig. 8. As will be observed, the shell is first broken as nearly as possible into halves and then, while the egg is poured from 1/2 of the shell into the other, the white is dropped into a dish and the yolk is retained in the shell. During this process, the yolk should remain intact in its delicate membrane, for if it becomes mixed with the white the lightness of the white will be injured. To separate the yolk from the white is not difficult when eggs are fresh, but as they become stale the membrane surrounding the yolk grows weak and breaks easily. If the yolk breaks and any of it falls into the white, it must be completely removed before the white is beaten.
39. BEATING OF EGGS.--Sometimes eggs are cooked in the shell and other times they are used alone just as they are removed from the shell, as in the frying and poaching processes; however, when they are to be combined with other ingredients, they are usually beaten. Eggs are beaten for the purpose of mixing the yolk and the white or of incorporating air to act as a leavening agent when the [Illustration: FIG. 9] eggs are heated in the cooking process. Various utensils, such as a fork, an egg whip, or an egg beater, may be employed for beating eggs, the one to select depending on the use to which the eggs are to be put. The rotary, or Dover, egg beater, previously described as a labor-saving device and illustrated in Fig. 9 (a), should be used to beat either whole eggs or the yolks of eggs when they are to be used in custards, mayonnaise, cakes, puddings, etc., as it will beat them sufficiently light for such purposes. However, for the beating of egg whites, use should be made of a fork or of an egg whip similar to that shown in (b), because the whites must be lifted instead of stirred for the incorporation of air, and it is only with a utensil of this kind that this can be accomplished. Then, too, more air can be incorporated into the whites and the volume of the egg thereby increased by means of a fork or an egg whip than by an egg beater. An important point to remember in this connection is that eggs can be beaten more successfully when they are cold and have had a pinch of salt added to them.
40. 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, as shown in Fig. 10, when they do not stand up nor cling to the whip; whereas, for other purposes, as in making meringue, they are beaten until they are stiff enough to stand up well and to adhere to the whip, as Fig. 11 shows. When egg whites are to be beaten stiff, care should be taken not to continue the beating too long. If this is done, they will become dry and will break up into small pieces, a condition that will mean a loss of some of the air that has been incorporated. 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 they 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.
POINTS TO OBSERVE IN COOKING EGGS
41. 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 consistency 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.
42. 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.
43. 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.