A. Class Experiment. Solubility of Egg White.
1. Cut a small piece of uncooked egg white with a pair of scissors. Shake the egg white with some cold water. Filter. Has any of the egg white dissolved? Find out by testing as follows: a. Boil some of the filtered water. What happens?
b. Add nitric acid to a second portion and boil. Cool, and add ammonia. Note color given.
c. Try the effect of the acid and ammonia on some of the egg white itself. Egg white contains large amounts of protein, and protein gives the color with the acid and ammonia.
2. Repeat the experiment, but use water which is nearly boiling to shake with the egg.
B. Class Experiment.
1. Drop one teaspoon of egg white into a pan of water which is at about 150° F.
2. Repeat, but have the water boiling hard and let it continue boiling for a moment or two.
3. Repeat, but have the water just below boiling.
Why does the egg white spread in one, and break up in another? In which is the temperature too high to give the cooked egg a good consistency?
C. Poach an Egg. From the results obtained in the previous experiment, account for the temperature of the water suggested in the following recipe. While it is desirable, the muffin ring is not essential. Serve on toast. What will happen if the water used is too cold? Too hot?
Dropped Eggs. (Poached)
Have ready a shallow pan two-thirds full of boiling, salted water, allowing one-half tablespoon of salt to one quart of water. Put two or three buttered muffin rings in the water. Break each egg separately into a cup, and carefully slip into a muffin ring. The water should cover the eggs. When there is a film over the top, and the white is firm, carefully remove with a buttered skimmer to circular pieces of buttered toast, and let each person season his own egg with butter, salt, and pepper.
From the "Boston Cooking-School Cook Book." By Fannie M. Farmer.
The United States government bulletin on eggs tells us that "perhaps no article of diet of animal origin is more commonly eaten in all countries or served in a greater variety of ways." But eggs are even more interesting when it is remembered that, like milk, they are a complete food intended for the sole nourishment of the young animal. They must, of course, contain everything that is needed for growth. Even after what has been said about the need for water, it may be a surprise to learn that the edible portion of eggs is about three-fourths water, averaging about seventy-four per cent. The amount of protein present is high, fourteen and a half per cent; and this, together with the large amount of fat, ten and a half per cent, makes eggs rank with milk and meat in the diet. Then the ideal form of the iron and phosphorus present in the mineral matter adds to the value of eggs from the dietetic standpoint, and they are probably even better building material than meat. This nutriment is not divided evenly between the white and yolk, for the white contains more water and less protein and mineral matter than the yolk; and practically all the fat is found in the latter. This highly nutritious yolk is intended to be the first source of food for the embryo chick. This embryo can usually be seen as a tiny dark speck lying close to the yolk. The white is food used at a later stage.
The problem in buying eggs is to obtain them fresh, and the term fresh is by no means the same as new-laid. The new-laid egg is, of course, the most desirable grade, but often can be had only at an exorbitant price quite beyond the pocketbook of the average person. Eggs, like other foods, are affected by bacteria. The shells are a partial protection, but since they are porous, bacteria can enter and soon begin the process of decay. The earliest change is mainly in flavor. Later, the membrane which surrounds the yolk is partially absorbed and it becomes difficult to separate the yolk from the white. The white can never be beaten stiff and dry if part of the yolk is mixed with it. An egg kept too long in cold storage often will have a white which will not beat properly.
As eggs do not keep long under usual conditions and as hens do not lay uniformly throughout the year, many methods of preserving eggs have been tried. The most successful method for home use is a water-glass solution. This substance, which is a silicate of potassium or sodium, or a mixture of the two, can be bought as a syrupy liquid at a few cents a pound and diluted with ten times its volume of water. The water used should be pure and is better boiled and cooled before mixing. The diluted water-glass is poured over the eggs so as to cover them completely, and then they must be put into a cool place. This method is not only the easiest to use, but also the one that keeps the eggs best and with least disagreeable flavor. Eggs laid in April, May, and June are the best to use for this purpose, as they seem to keep most satisfactorily. The best method of all for keeping eggs is cold storage, and such eggs in certain seasons are about all that are on the market. Eggs which have been kept in this way will rattle somewhat when shaken, because of the evaporation which may have gone on, and yet be fresh enough for use.
Eggs should be washed before use. As the mucilaginous substance on the outside of the shell helps to render it less porous, it is better not to wash the shell until the egg is to be used.
Eggs are becoming costly, and it is necessary to consider this in their use. Many recipes which call for eggs for thickening can be modified so that flour or starch may be substituted for all or at least some of the eggs, and baking powder may take the place of the egg used for leavening.
For most people eggs are an easily and completely digested food. Sometimes an uncooked egg swallowed whole causes disturbance, because it has not sufficient flavor to start the flow of the digestive juices, and since the egg is not broken up, what ferment is present cannot well get at it. A raw egg beaten up with a little milk is much less apt to cause trouble. Eggs cooked in any way are very completely digested, and the ordinary person does not have to consider the small differences in digestibility which result from different methods of cooking. Even hard-boiled eggs, if they are not swallowed in lumps instead of being properly masticated, can be included in this statement. A soft-cooked egg is, however, more acceptable to most people than one that is hard-boiled.
U. S. Dept. of Agriculture.
Farmers' Bulletin No. 87. "Food Value of Eggs."
Farmers' Bulletin No. 103. "Preserving Eggs."
Farmers' Bulletin No. 122. "Selling Eggs by Weight." "Flavor of Eggs." Farmers' Bulletin No. 128. "Eggs and their Use as Food." Farmers' Bulletin No. 190. "Cost of Eggs in Winter." Cornell Reading Course. "Preservation of Foods," Pt. III, pp.
299,300. Connecticut Exp. Station Bulletin, No. 55. "Infection and Preservation of Eggs." Office of Exp. Station Bulletin, No. 43. "Comparison of Digestibility of Potatoes and Eggs."
1. How can the freshness of an egg be determined before breaking?
2. Why does an egg become stale?
3. Are cold-storage eggs good food?
4. What is the best method of preserving eggs at home?
5. Why should eggs that are to be kept for some time not be washed before being put away?
6. Why must precaution be taken against putting eggs away near strong-smelling foods?
7. Why should eggs be washed before breaking?
8. What use is made of egg shells?
9. How many eggs of average size in a pound?
10. What were the maximum and minimum prices of eggs during the past year? At what season of the year are eggs most expensive ? Cheapest?
11. Why are eggs valuable as food?