Fats and Oils.
Fats and oils contain three elements--carbon, oxygen and hydrogen.
About one-fifth of the body is composed of fat. Before death results
from starvation 90 per cent. of the body fat is consumed.
USES OF FAT.
(1) To furnish energy for the development of heat; (2) to supply
force; (3) to serve as covering and protection in the body; (4) to
lubricate the various structures of the body; and (5) to spare the
tissues. The fats and oils used as food all serve the same purpose,
and come before the carbohydrates in fuel and force value; in
combination with proteids, they form valuable foods for those engaged
in severe muscular exercise, such as army marching, mining
expeditions, etc.
Fats and oils are but little changed during digestion. The fat is
divided into little globules by the action of the pancreatic juice and
other digestive elements, and is absorbed by the system. Fat forms the
chief material in adipose tissue, a fatty layer lying beneath the
skin, which keeps the warmth in the body, and is re-absorbed into the
blood, keeping up heat and activity, and preserving other tissues
during abstinence from food. Fat sometimes aids the digestion of
starchy foods by preventing them from forming lumpy masses in the
mouth and stomach, hence the value of using butter with bread,
potatoes, etc. The animal fats are more nutritive than the vegetable,
butter and cream heading the list. Cooking fats at a very high
temperature, such as frying, causes a reaction or decomposition, which
irritates the mucous membrane and interferes with digestion.
The principal animal fats are butter, cream, lard, suet, the fat of
mutton, pork, bacon, beef, fish and cod liver oil. The vegetable fats
and oils chiefly used as food are derived from seeds, olives, and
nuts. The most important fats and oils for household purposes are:
BUTTER.
Butter, which contains from 5 to 10 per cent. of water, 11.7 per cent.
fat, 0.5 per cent. casein, 0.5 per cent. milk sugar (Konig). The
addition of salt to butter prevents fermentation. Butter will not
support life when taken alone, but with other foods is highly
nutritious and digestible.
CREAM.
Cream is one of the most wholesome and agreeable forms of fat. It is
an excellent substitute for cod liver oil in tuberculosis. Ice cream
when eaten slowly is very nutritious.
LARD.
Lard is hog fat, separated by melting.
SUET.
Suet is beef fat surrounding the kidneys.
COTTOLENE.
Cottolene is a preparation of cotton-seed oil.
OLEOMARGARINE.
Oleomargarine is a preparation of beef fat provided as a substitute
for butter.
OLIVE OIL.
Olive oil is obtained from the fruit, and is considered to be very
wholesome; in some cases being preferred to either cod-liver oil or
cream for consumptives.
COTTON SEED OIL.
Cotton seed oil is frequently substituted for olive oil.
NUTS.
Nuts contain a good deal of oil.