Composition of the egg.—Figure 40 gives the composition of the yolk and white taken together, and of the yolk and white separated. The protein content is high, and the fat content as well, the yolk containing a higher percentage of these two foodstuffs than the white. The mineral matter is of high value, iron and phosphorus being found in ideal forms in the yolk. In using the egg as food we are availing ourselves of one of nature’s richest storehouses. A single egg of average size yields about 75 calories, of which 60 come from the yolk and 15 from the white. A very large egg, weighing two and two thirds ounces, will yield 100 calories.
Fig. 40.—Composition of eggs and cheese.
Fresh eggs and cold storage eggs.—The fresh-laid egg is always desired for its delicious flavor, and this flavor changes but little in a week or two if the egg is kept cool. It is desirable to preserve eggs, however, for future use at the season when they are most abundant and cheap. Many methods have been tried, such as laying them away in sawdust, sinking them in water-glass solution, or coating the shell with paraffin or some other substance to prevent evaporation and the entrance of air. The introduction of cold storage on a large scale promises a solution of the problem. If eggs are fresh when placed in storage, it is possible to keep them just above the freezing temperature for months without appreciable deterioration.
Eggs too long in storage may be detected by the musty odor and flavor, the running of the yolk into the white, and the thin quality of the white which prevents beating stiff. Some states have already passed stringent laws in regard to the sale of cold storage eggs.
The cost of eggs and how to buy.—The demand for fresh eggs is great, and so many eggs are exported, that the price is high, even in the summer. Twenty-five cents a dozen is a reasonable price, but this is below the average at the present
date. The thirty-five or forty-cent daily allowance for food will permit the moderate use of eggs at thirty-five cents a dozen, but not a liberal use in cakes and desserts. They should be used at such a price and with that allowance as the main dish for breakfast or luncheon at times, and not in sweet dishes calling for three or four eggs. If a recipe for soft custard calls for three eggs to a pint of milk, leave out one egg or even two, and use one or two tablespoonfuls of cornstarch instead. Select eggs with a hard shell, and yolk of rich yellow. If the shell is soft and the yolk pale, these deficiencies should be reported, as they can be corrected by the poultryman. The difference in color of the shells, whether white or brown, is not of great consequence. If you can buy eggs by the crate direct from the poultryman, this is a saving, provided the eggs can be used before they deteriorate. A small crate holds fifteen dozen; the usual size thirty dozen. Some express companies have a special rate for eggs, and parcel post should aid in this method of buying.
Relative digestibility of soft and hard-cooked eggs.—The fact must be recalled that to digest is to dissolve, and that the digestion of food means a dissolving by the digestive juices, aided by water. When we speak of the digestibility of food we may mean the ease and comfort of digestion, or the length of time taken by the process, or the completeness of the process. If we take the third of these meanings, hard-cooked egg is as digestible as the soft-cooked or the raw egg, because it is completely dissolved in digestion in the course of time. If the second meaning of digestion is taken, the hard-cooked egg may be slightly less digestible, for a slightly longer time is consumed in the process. The latest researches, however, show that the digestive process is longer with any food than was formerly supposed, and the difference in this case is not especially important. Indeed, we must accept
the conclusions of the scientist and frankly admit that the differences of temperature in cooking of egg do not have any great effect upon its digestibility.