[Sidenote: Composition of lean meat]
Lean meat is composed of the muscles of the animal. Approximately it is
70 per cent water, 20 per cent protein, and 10 per cent fat. The protein
is composed of connective tissue, which is a tough, fibrous substance
that forms tendons, and holds the muscle-cells in place. Chemically,
connective tissue is formed of albuminoids, which were discussed in
Lesson IV. These substances are somewhat difficult to digest, and are
not of very great importance in the human body, as they cannot take the
place of true proteid in tissue-formation.
The percentage of connective tissue in flesh depends upon the cut of
the meat. As every housewife knows, the cheapest cuts of meat contain a
larger amount of this material.
The gelatin of commerce is a manufactured product derived from the
connective tissue of animals.
Other forms of protein are globulin and myosin, which form the actual
muscle-substance. These elements form perhaps three-fourths of the
entire proteid of the animal, and are the most valuable substances of
flesh food. A very small portion of meat proteids is formed by the
free albumins of the blood, which are mechanically retained in the
muscle-cells, the purpose of which is the nourishment of the animal, and
therefore are not unwholesome as food.
[Sidenote: Meat extractives and their composition]
Another class of nitrogenous substances found in flesh foods is called
meat extractives. Though they exist only in quantities of from one to
two per cent of the weight of the flesh, they are the most interesting
from the standpoint of chemistry, because they are found only in flesh
foods, and are products only of cell life, hence not wholesome as food.
They are composed of urea, uric acid, creatin, etc., and are similar or
identical to the waste-products of human cell metabolism. The amount of
these substances contained in flesh depends upon the condition of the
animal at the time of slaughter, being much greater in animals slain
after the chase, or laboring under fear or abuse.
The chemical composition of the different cuts of meat does not vary
greatly, except in a greater or less per cent of fat, and no chemical
calculation can compute this accurately, as the fat in every cut of meat
varies widely.
[Sidenote: Prejudice against the hog]
Beef and mutton are comparatively the same in both nutritive value
and popularity, but the use of pork has been generally condemned the
world over. The reason for this is probably explained by prejudices of
tradition and religion, rather than by scientific or hygienic knowledge.
The prejudice against swine because of the filthy habits of the animal
is more a matter of sentiment than of science. It is sometimes the
custom among farmers to confine hogs in a pen, and to feed them upon
swill and garbage. This makes of the animal a filthy creature. However,
when left in the open fields or woods, they are as cleanly in their
habits as any of their brother animals. Corn and alfalfa-fed pork is
equally as wholesome as beef or mutton, when prepared in a similar
manner, and eaten in temperate quantities, while the hog fattened upon
acorns and herbs, in his native habitat (the woods), is much more
healthy, and his flesh really superior to most of his brother animals.