An an egg is particularly rich in nitrogenous elements. It is indeed one of the most highly concentrated forms of nitrogenous food, about one third of its weight being solid nutriment, and for this reason is often found serviceable in cases of sickness where it is desirable to secure a large amount of nourishment in small bulk.
Composition of the white of an ordinary hen’s egg.
Composition of the yolk.
The white of egg is composed mainly of albumen in a dissolved state, inclosed in layers of thin membrane. When beaten, the membranes are broken, and the liberated albumen, owing to its viscous or glutinous nature, entangles and retains a large amount of air, thus increasing to several times its original bulk.
The yolk contains all the fatty matter, and this, with a modified form of albumen called vitellin, forms a kind of yellow emulsion. It is inclosed in a thin membrane, which separates it from the surrounding white.
The yolk, being lighter than the white, floats to that portion of the egg which is uppermost, but is held in position by two membranous cords, one from each end of the egg. The average weight of an egg is about two ounces, of which ten per cent consists of shell, sixty of white, and thirty of yolk.
Egg yolks have more protein, which is good, but they also have more fat so more calories than white eggs. Yolks are good in moderation eating but depends to your kind of weight loss diet.
How to Choose Eggs.
The quality of eggs varies considerably, according to the food upon which the fowls are fed. Certain foods communicate distinct flavors, and it is quite probable that eggs may be rendered unwholesome through the use of filthy or improper food; hence it is always best, when practicable, to ascertain respecting the diet and care of the fowls before purchasing eggs.
On no account select eggs about the freshness of which there is any reason to doubt. The use of stale eggs may result in serious disturbances of the digestive organs.
An English gentleman who has investigated the subject quite thoroughly, finds upon careful microscopical examination that stale eggs often contain cells of a peculiar fungoid growth, which seems to have developed from that portion of the egg which would have furnished material for the flesh and bones of the chick had the process of development been continued. Experiments with such eggs upon dogs produce poisonous effects.
There are several ways of determining with tolerable accuracy respecting the freshness of an egg. A common test is to place it between the eye and a strong light. If fresh, the white will appear translucent, and the outline of the yolk can be distinctly traced. By keeping, eggs become cloudy, and when decidedly stale, a distinct, dark, cloud-like appearance may be discerned opposite some portion of the shell. Another test is to shake the egg gently at the ear; if a gurgle or thud is heard, the egg is bad. Again, eggs may be tested by dropping into a vessel containing a solution of salt and water, in the proportion of a tablespoonful to a quart. Newly laid eggs will sink; if more than six days old, they will float in the liquid; if bad, they will be so light as to ride on the surface of the brine. The shell of a freshly laid egg is almost full; but owing to the porous character of the shell, with age and exposure to air a portion of the liquid substance of which the egg is composed evaporates, and air accumulates in its place at one of the extremities of the shell. Hence an egg loses in density from day to day, and the longer the egg has been kept, the lighter it becomes, and the higher it will rise in the liquid.
An egg that will float on the surface of the liquid is of too questionable a character to be used without breaking, and is apt to be unfit for use at all.
Eggs for boiling may be preserved by placing in a deep pan, and pouring scalding water over them. Let them stand half a minute, drain off the water, and repeat the process two or three times. Wipe dry, and when cool, pack in bran.
Eggs should be kept in a cool, not cold, place and handled carefully, as rough treatment may cause the mingling of the yolk and white by rupturing the membrane which separates them; then the egg will spoil quickly.
The time required for the digestion of a perfectly cooked egg varies from three to four hours.
It is generally conceded that eggs lightly cooked are most readily digested. What is generally termed a hard-boiled egg is not easily acted upon by the digestive juices, and any other manner of cooking by which the albumen becomes hardened and solid offers great resistance to digestion.