Woman's Institute Library of Cookery Volume II Part 9

7. PROTEIN IN EGGS.--The nature of the food substances in eggs is of nearly as great importance as their amount, for they not only determine the value of this food in the body, but influence its cooking. That protein is present in both the yolk and the white is apparent from the fact that they coagulate when heat is applied. Because eggs are high in protein, containing 14.8 per cent. of this substance, they may be regarded as equivalent to a meat dish, and it is only when they are extremely high in price that they cannot be frequently subst.i.tuted for meat to advantage. They are often used to take the place of milk, too, for eggs and milk are more alike in nutritive value than any other two protein foods; but, of the two, milk yields the cheaper form of protein.

Like meat and milk, eggs are rich in all those food materials which enter into the construction of bone, muscle, and blood.

8. FAT IN EGGS.--A study of the food chart previously mentioned will show that eggs contain proportionately almost as much fat as protein and that nearly all this fat is found in the yolk. Since fat produces more heat or energy, weight for weight, than any other food substance, and since eggs contain neither starch nor sugar, it is evident that the fat of this food is the main source of the energy-producing material. Fat in eggs occurs in the form of an emulsion, or tiny particles, and, like the fat of milk, is very readily digested. It is for this reason that both of these foods are particularly well adapted to the diet of both children and adults. The presence of quant.i.ties of protein and fat and the absence of carbohydrate in eggs indicate that the proper thing to combine with this food, in order to have a well-balanced meal when eggs are eaten, is carbohydrate in some form.

9. MINERALS IN EGGS.--Eggs are especially valuable for the mineral salts they contain, chief among which are lime, phosphorus, sulphur, iron, pota.s.sium, and sodium. For this reason, the addition of eggs to any kind of diet supplies a large amount of the minerals that are needed for bone, blood, and tissue building. A favorable point concerning the minerals found in eggs is that they are not affected to any extent by cooking. Therefore, in the preparation of any dish, if eggs are added to other foods, that dish will contain an additional amount of mineral salts, plus the nutritive value of the eggs.

10. DIGESTIBILITY OF EGGS.--In connection with the discussion of the food substances of which eggs are composed, it will be well to note how these affect the digestibility of this food. But just what is meant by this characteristic with reference to eggs must first be understood. In some foods, digestibility may mean the length of time required for them to digest; in others, the completeness of the digestion; and in still others, the ease and comfort with which the process of digestion proceeds. In the case of eggs, digestibility refers to the quant.i.ty of this food that is absorbed, that is, actually dissolved and permitted to enter the blood stream. The nutritive value of eggs is not so high as would naturally be supposed, for, although the protein, fat, and mineral salts of an egg make up about one-fourth of its contents, one egg equals in nutritive value only 1/2 cupful of milk, a small potato, or a medium-sized apple. However, when the proportion of the nutritive material that the body retains from this food, or its digestibility, is considered, eggs rank extremely high, it having been determined by experiments that 97 per cent. of the protein and 95 per cent. of the fat are a.s.similated. A point worthy of note in this connection, though, is that eggs contain no cellulose, such as that found in grains, vegetables, and fruits. Therefore, in order to add the much-needed bulk to the diet, foods that do contain cellulose should be served with eggs.

11. Whether or not the cooking of eggs has any effect on their digestibility is a matter that has also been investigated. The results of the experiments made indicate that cooking makes some difference with the rate of digestion, but very little with its thoroughness. So far as the rapidity of digestion is concerned, there is very little difference between raw eggs and slightly cooked eggs; but hard-cooked eggs, although they may be digested as completely as soft-cooked ones, require longer time for the accomplishment of the process. This is due to the fact that the whites of hard-cooked eggs are so firm in texture that, unless they are finely chopped or thoroughly masticated, the digestive juices are not able to act on them quickly. As a result, portions of them may escape digestion or remain in the digestive tract for some time and decompose. For this reason, hard-cooked eggs are usually excluded from the diet of children and invalids, and even healthy adults should be careful to masticate them thoroughly.

SELECTION OF EGGS

12. On first thought it would seem as if there is very little to guide the housewife in the selection of eggs, it being extremely difficult to tell from their external appearance whether or not they are fresh or stale. As a rule, she must trust largely to the honesty of the person from whom she buys eggs. Still she need not depend entirely on the dealer's word, for, at least to a certain extent, there are ways in which she may judge the quality of eggs. Because of the great value of eggs as a food and for cooking purposes, it is important that the housewife make use of all available information on this matter and, in addition, become familiar with the trade practices in the egg industry.

13. MARKETING OF EGGS.--As is generally known, hens lay a large number of eggs in the spring of the year, but they do not lay readily in the cold winter months; and not alone are the greatest quant.i.ties of eggs produced in April and May, but those laid at this time are of the best quality. Because of this condition and in order that the demand during the time of scarcity may be supplied, it is necessary that a considerable number of eggs be preserved when they are comparatively cheap and abundant. Also, in the preserving of eggs for future use, it is of the greatest importance that they be kept in the best possible condition and manner, so that when they are used, months after they are laid, they may be as good as it is possible to have them.

The advance made in storage and transportation methods in recent years has done much toward making the egg supply uniform all the year around.

Not long ago, because of inadequate means of storage and shipping, eggs were sold only a short distance from the place where they were produced.

However, with the coming of cold storage and improved methods of shipping, eggs have been changed from a perishable and more or less seasonable food to a staple one. Now it is possible to collect them in large quant.i.ties, to keep them for a considerable time before selling them, and to ship them long distances. To safeguard the public, though, authorities have set a time limit for the storage of eggs, the legal time they may be kept being 8 months. By this is meant that eggs placed in the warehouse in May must be released or sold in December; whereas, those stored in June must be released no later than January.

14. Eggs that have been kept too long in storage are characterized by a musty odor and flavor, the breaking of the yolk and its mixing with the white, and a watery condition of the white. Such eggs, of course, cannot be sold legally. Those which may be placed on the market are graded according to their freshness, cleanliness, size, cracks, and color. With the exception of their freshness, these points can be readily told from the appearance of the eggs; but, in order to determine whether an egg is fresh or not, it is generally put through a process known as _candling_, by which the interior condition of the egg can be ascertained.

In the grading of eggs, all those of the best size, color, and condition are sold under a particular trade name and bring a high or a low price, according to the grading. Others that are not so perfect are put in another grade and sell for prices that vary according to the demand.

Eggs, of course, differ in appearance and in many cases they are sorted in order to satisfy the demand. For instance, in some localities, eggs having a brown sh.e.l.l sell for the highest price, while in other places, eggs having a white sh.e.l.l are in the greatest demand and bring the highest price. Unsorted eggs are not held in much favor and do not bring so good a price as those which are all one color. Many persons have an idea that the color of the sh.e.l.l of an egg bears some relation to its nutritive value and flavor. However, authorities on foods agree that, other things being alike, the edible portion of white-sh.e.l.led eggs has essentially the same composition and nutritive value as that of dark-sh.e.l.led eggs.

15. QUALITY OF EGGS.--The natural quality of eggs depends largely on the food of the hens and their conditions of living. Because of this fact, the selection, breeding, and care of fowls have developed into a science, particularly since the production of eggs has grown into an industry. When the quality itself is to be determined, all the characteristics of eggs must be taken into consideration; still there is one particular point on which the quality of eggs depends, and that is their freshness. Various agencies, however, are constantly at work to render this quality inferior. Chief among these are the molds and bacteria that pa.s.s through the porous sh.e.l.ls of eggs that have been improperly cared for or have become contaminated by being allowed to remain in unclean surroundings. Such bacteria are responsible for the unpleasant flavors that are found in bad eggs. Because of their harmful effect, every effort should be made to prevent the entrance of the germs that cause decay, and, as has been stated, the best way in which to accomplish this is to protect the sh.e.l.l. If it is found that bacteria have entered, the eggs will become unfit for use quickly unless their growth is prevented. This may be done by storing the eggs at a temperature that will keep the bacteria dormant, or inert.

16. If the eggs are kept under the proper conditions, they will not actually spoil for a long time; but it is seldom that they are not more or less affected by storage of any kind that covers a period of several months. One change that can always be looked for in such eggs is in the air s.p.a.ce at the broad end. When an egg is first laid, this air s.p.a.ce is small, but since the water contained in the egg slowly evaporates through the porous sh.e.l.l it increases in size as the egg grows staler.

For this reason, the freshness of an egg can often be determined by the size of this air s.p.a.ce.

In addition, the purposes for which eggs are used are somewhat affected by their storage. A stale egg, although it may not be actually spoiled to the extent that it cannot be used as food, will not produce such good results in a cooking process as a fresh egg, especially if it is used for leavening. In fact, it is impossible to produce the desired results with eggs that have undergone a certain amount of change, even though their odor and their flavor do not indicate that they are spoiled.

17. JUDGING THE QUALITY OF EGGS IN THE MARKET.--While, as has been mentioned, the housewife must depend considerably on the dealer's word as to the freshness of the eggs she purchases, it will be well for her to be familiar with the trade names of eggs and their meaning. The names used differ, of course, in various localities, but all large distributors grade and name eggs in much the same way. In deciding on the grade to which eggs belong, a certain number of points are given for color, size, freshness, and appearance, and the sum total of these points determines the grade, a special name being given for each grade.

For instance, eggs that can be graded 90 are called _extra fancy_; those which receive a grade of 80, _fancy_; those which are graded 70, _strictly fresh_; and those which can be graded only 60, _cooking eggs_.

When eggs are put on the market under such names, it can be expected that the quality will correspond to the grade and the price will vary with the grade. Therefore, the trade name and the price are two of the princ.i.p.al ways in which the quality of eggs in the market may be judged.

18. Another way of judging the quality of eggs consists in observing the condition of the surface of the sh.e.l.l. When eggs are freshly laid, the sh.e.l.l is covered with a substance, called _bloom_, that gives it a feeling much like that of a thin lime coating deposited in a pan after water boils. This coating disappears gradually as the egg is exposed to the air, but as long as it remains, the egg may be considered as fresh and germ-proof. While this way of determining freshness is probably the quickest, it is possible that the quality of some eggs from which the bloom has recently disappeared has not been injured.

19. When eggs are selected in the market, certain points in their appearance should also be noted. If eggs of the best quality are desired, medium-sized ones that are uniform in size and color should be selected. With regard to shape, they should have a comparatively long oval sh.e.l.l, one end of which is blunt and the other, a sharp curve.

[Ill.u.s.tration: FIG. 2: Internal structure of egg.]

[Ill.u.s.tration: FIG. 3: FRESH, 3 WEEKS, 3 MONTHS, OLDER.]

20. JUDGING THE QUALITY OF EGGS IN THE HOME.--After eggs have been received in the home, several simple tests for determining their freshness can be applied in addition to the ones already mentioned. A rather indefinite test, but one that is sometimes applied to determine the freshness of an egg, is to shake it. However, to be able to carry out this test successfully, it is well to understand the interior structure of an egg. Fig. 2 ill.u.s.trates this clearly. At _a_ is shown the air s.p.a.ce previously mentioned; at _b_, the spiral cords that run from the yolk to each end of the egg and hold the yolk in place; at _c_, the yolk; and at _d_, the white. When the water inside the sh.e.l.l evaporates, the yolk and white shrink so much that they can be felt moving from side to side when the egg is shaken. The staler the egg, the more p.r.o.nounced does the movement become. This method should be applied only immediately before the egg is to be used, as the thin membrane between the yolk and the white and the spiral cords that hold up the yolk are liable to be disturbed by the shaking. If they are broken, the yolk will settle and finally adhere to the sh.e.l.l in case the egg is stored for any length of time after that.

[Ill.u.s.tration: FIG. 4: Testing the egg.]

[Ill.u.s.tration: FIG. 5: four eggs.]

21. If nothing has been done to preserve eggs, the simple test for freshness ill.u.s.trated in Fig. 3, which consists in placing the eggs in a gla.s.s containing water, will be found effective. A perfectly fresh egg will sink when it is put into the water, but if the egg is 3 weeks old the broad end will rise slightly from the bottom of the gla.s.s. An egg that is 3 months old will sink into water until only a slight portion of the sh.e.l.l remains exposed; whereas, if the egg is older or stale, it will rise in the water until nearly half of it is exposed. 22. The test known as candling, which is usually applied to eggs before they are put on the market, can also be practiced by the housewife in the home.

This method of determining the freshness of eggs consists in placing a piece of cardboard containing a hole a little smaller than an egg between the eye and a light, which may be from a lamp, a gas jet, or an electric light, and holding the egg in front of the light in the manner shown in Fig. 4. The rays of light pa.s.sing through the egg show the condition of the egg, the size of its air s.p.a.ce, and the growth of mold or the spoiling of the egg by any ordinary means.

[Ill.u.s.tration: FIG. 6 (_a_) (_b_)]

In Fig. 5 is shown how an egg at various stages of freshness appears when candled. When an egg is fresh, it will appear as in (_a_); that is, the yolk will be barely distinguishable from the white except as a slightly darker area in the center of the egg, and the entire egg will appear clear and bright and free from spots. In an egg that is a little older, candling will reveal a slightly darker yolk, a cloudy white, and a larger air s.p.a.ce, as in (_b_). In a watery egg, or one that is beginning to spoil, various dark spots and blotches usually develop, as view (_c_) indicates. When an egg is rotten, the contents of the sh.e.l.l will look dark in candling and the yolk will appear to be mixed with the white, as in (_d_). 23. If the housewife does not wish to resort to candling, she may determine the condition of an egg by breaking it into a saucer and examining it carefully. If the egg is newly laid, no odor will be detected and the white will be clear, elastic, and rather thick; also, where it joins the yolk it will be almost solid. The yolk of such an egg will have an even yellow color, without lighter or darker spots and, as shown in Fig. 6 (_a_), will stand up well from the surface of the white. Sometimes a small spot of blood may be detected on the yolk of a perfectly fresh egg, but, while this is not pleasant to look at, it does not affect the quality of the egg. When an egg that is not real fresh is broken into a saucer, the yolk will lie flat, as in (_b_). In an egg that is quite stale, the membrane surrounding the yolk is easily destroyed, so that even when such an egg is broken carefully the yolk and the white are likely to run together.

PRESERVATION OF EGGS

CAUSES AND PREVENTION OF DETERIORATION

24. As has been implied in the discussion given thus far, eggs will deteriorate or spoil in a comparatively short time unless something is done to preserve them. In view of the eggs she keeps on hand at home, as well as those she buys, the causes of spoiling and the ways in which to prevent spoiling are matters with which the housewife should be familiar, particularly if she would secure for her family eggs of the best quality at prices that are not beyond her means. The spoiling of eggs is due to decomposition, which is caused by molds or bacteria that result from accidental causes, and, in fertile eggs, to the germination and development of the chick, which is a natural process. The loss of quality resulting from molds and bacteria in the egg is brought about by their growth and by the formation of chemical compounds, which give spoiled eggs their peculiar appearance, taste, and odor. Some of these molds are not injurious to health, while others may give rise to more or less serious illness.

25. Various methods have been devised whereby their rapid deterioration may be prevented, and a knowledge of these is important to those who have occasion to purchase eggs or to keep them over from the season of plenty to the season of scarcity. The method followed to prevent losses due to the development of the embryo consists in the production of infertile eggs--that is, eggs that are non-productive. This is a point that is as well worth remembering in the home production of eggs as it is in professional poultry raising. The method employed to prevent the infection of eggs by molds and bacteria is to keep them clean and dry from the time they are laid until they are finally used.

26. While the preservation of eggs is carried on to a greater extent at present than formerly, the idea is neither new nor original; indeed, it has been practiced for many years by the people of some foreign countries. For instance, in some sections of China, duck eggs are preserved by covering them with a layer of mud, and such eggs are often kept for a year or more before they are eaten. However, eggs stored in this way decompose and their odor and flavor disappear before they are used, so that they must usually be hard boiled before they can be eaten.

Egg preservation such as is practiced in the United States is the opposite of this and attempts to prevent not only ripening processes and putrefactive changes but any bacterial or other changes that lessen the original quality. It will be well to note, however, that eggs preserved for any length of time deteriorate to some extent and cannot be expected to be equally as good as fresh eggs.

COMMERCIAL PRESERVATION OF EGGS

27. The usual market method of preserving eggs is by cold storage, an industry that has developed to vast proportions in recent years. The success of this method depends on the fact that germs causing decomposition will not live in a low temperature. While the plan of storing eggs is responsible for their high price at certain times, it is also a means of supplying eggs to many persons who would otherwise not be able to obtain them. The greatest point in favor of this plan, however, is that it makes possible the marketing of quant.i.ties of eggs during the winter season of scarcity at a price that, although somewhat high at times, is much more moderate than it would be if it were not possible to store eggs in large quant.i.ties.

28. In order that advantage may be taken of favorable climatic conditions, eggs are commonly purchased for storage as early in the year as they are abundant. They are selected with great care, only those which are clean, sound, and fresh being used. These eggs are packed in clean cases, and then placed in warehouses where they are kept at a temperature just above freezing, or one that ranges from 32 to 40 degrees Fahrenheit. In such storage, precaution is usually taken to prevent the eggs from freezing, for while freezing does not necessarily injure them for immediate use it breaks the sh.e.l.l because of the contraction that occurs. While the eggs are in storage, they are also protected as far as possible from air circulation, as this increases evaporation and causes the contents of eggs to shrink. To prevent the yolks from settling to one side, and finally adhering to the sh.e.l.l, the eggs are turned frequently. The usual limits of storage are from 6 to 9 months, but eggs are not generally allowed to remain in storage more than 8 months. When taken out at the end of that time, it will be found that they have deteriorated very little, and while they cannot compete with the better grades of fresh eggs, they are as desirable as most of the eggs that can be purchased in the early fall when eggs are not plentiful.

29. Sometimes eggs are removed from the sh.e.l.ls, stored for commercial use in containers of about 50 pounds each, and kept at the freezing point until they are to be used. Eggs in this form, which may be bought with the yolks and whites either mixed or separate, find a ready market in bakeries and restaurants, where large quant.i.ties of eggs are continually used. Such eggs remain good for any length of time while they are kept frozen, but they must be used immediately after they are removed from storage.

30. It is not always necessary to keep eggs at a cold temperature in order to preserve them, for a method that has proved very satisfactory is to reduce them to the form of powder by drying them. In this form, the bulk is greatly reduced, 1 pound of the dry material representing 30 to 40 eggs, and in order to prepare them for use in cooking they must be mixed with water. POWDERED EGGS, or _desiccated eggs_, as they are usually called, can be kept for an indefinite length of time without special care in storage, when they are wholesome and carefully handled.

Tests that have been made show that eggs of this kind give fairly good results when used in cookery, but they are used princ.i.p.ally by bakers, for they can be obtained more cheaply than fresh eggs, especially when it is difficult to secure eggs in other forms.

HOME PRESERVATION OF EGGS

31. The housewife who desires to run her household on an economical basis will not depend entirely on eggs that are commercially stored, but will take advantage of one of the many methods by which eggs may be successfully kept in the home. By being prudent in this matter, she will be prepared to supply her family with this commodity at times when the market price is high.

As many as twenty household methods have been tried out for the preserving of eggs, but each one is based on the theory that decay is hindered when the sh.e.l.l is covered with some substance that renders it air-tight and prevents evaporation or the entrance of bacteria and mold.

Among the methods that have met with the most success are burying eggs in oats, bran, or salt; rubbing them with fat; dipping them in melted paraffin; covering them with varnish or sh.e.l.lac; and putting them down in lime water or in a solution of water gla.s.s.

No matter which of these methods is adopted, however, it will be well to note that only eggs laid in April, May, or June should be used for storage purposes, as these are the best ones laid during the year; also, that the eggs should always be packed with the small end down, because the yolk will not settle toward the small end so readily as toward the large end or the side.

32. Of these various ways of preserving eggs in the home, probably the oldest method is that of packing the eggs in oats, bran, or salt. This method is fairly effective, but the eggs preserved by it do not keep so long as eggs preserved by other methods, nor is their quality so good.

Preserving eggs by completely covering the sh.e.l.ls with fat, vaseline, paraffin, varnish, or other substance that will exclude the air but not impart flavor to the eggs, proves a more satisfactory method so far as the eggs are concerned, but it requires more time and handling. To a.s.sist in their preservation, eggs are sometimes immersed in boiling water for 12 to 15 seconds. This process, which causes the white to harden slightly just inside of the sh.e.l.l, keeps the eggs fairly well, but it is rather difficult to accomplish, as the least overcooking renders the egg unfit for use as a raw egg.

As a result of many trials, it has been found that putting eggs down in the various solutions that are used for this purpose is the most effective way of preserving them under home conditions, provided, of course, the solutions in which the eggs are immersed do not flavor the eggs. Therefore, to a.s.sist the housewife, detailed directions for using lime water and water gla.s.s for this purpose are here given.

33. PRESERVATION WITH LIMEWATER.--To prepare limewater for the preservation of eggs, dissolve 1 pound or 1 pint of salt and 1 quart of finely slaked lime in 3 gallons of water, stir the solution at frequent intervals for a day or two, and then allow the liquid to settle. Place the eggs in tall stone crocks or kegs with their pointed ends turned down, filling the receptacles to within a few inches of the top. Pour the clear limewater over the eggs so arranged, allowing it to rise an inch or two above the top layer. Then stand the vessel in a cool place where the temperature will not exceed 50 degrees Fahrenheit. Eggs so treated will keep for at least 6 or 8 months. The only objection to this plan is that the eggs preserved by it sometimes acquire a slight lime taste.