This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
The process of salting is a primitive but still desirable method of preserving meat and fish. Salted meat usually becomes pale from the action of the salt upon the haemoglobin contained in the blood vessels of the muscle fibre. The addition of a little saltpetre helps to preserve the original reddish colour of salted meat. Salt also absorbs moisture from the food, and thus dries it while preserving it.
Brine, a strong solution of common salt, may be used to temporarily preserve meat and other substances. The Chinese have long practised the art of preserving fruits, roots, and flowers in it. Corned beef is made by soaking the meat for some days in such a solution. The brine acts upon the muscular tissues and toughens it. Brine, concentrated by long-continued use, has been known to acquire poisonous properties from changes in the organic matter which has passed into it from the meat. The process of soak-20 ing in brine causes much of the extractives and natural salts of the meat to osmose out from it, and the loss of organic material and salts occurring in this way has been estimated by Liebig and Parkes as equal to fully one third, for myosin itself is soluble in strong salt solution. For these reasons salted meats, such as corned beef, require prolonged cooking. Salt meat of all kinds is drier, less digestible, and slightly less nutritious than fresh meat.
Food may be kept in a frozen condition almost indefinitely. On being thawed, it must be cooked immediately, otherwise decomposition may set in at once, and, omitting milk and cream, food is not easily eaten in an actual frozen state, excepting by the northern Eskimos, who take their meat in that form by preference.
Meat and fish may be kept for many days frozen in blocks of ice without losing much in flavour, but vegetables are not as good when cooked after freezing.
In 1867 Dr. Carl von Baer reported to the Royal Society of London the discovery in arctic Siberia of the body of a frozen mammoth, the meat of which was preserved. As this animal has been extinct since the days of prehistoric man, it afforded an illustration of the marvellous preservative power of intense cold. Another such animal was found, in 1799, being eaten by wolves in Siberia.
In 1861 the entire bodies of three Swiss guides, who forty-one years before had been buried by an avalanche over the Glacier de Boissons, were found in a state of excellent preservation. With these examples of the influence of cold, it is little wonder that meat may be preserved for a few months in ice and yet be quite fit to eat. In freezing meat for export it is subjected to a temperature of about 200 F. below zero. When quite hard the carcass is sewn in thin cotton cloth and placed in a refrigerating chamber on shipboard, where it keeps in good condition throughout long voyages.
Meat actually frozen should be cooked as soon as it is thawed, and meat thus preserved is better cooked by roasting than boiling, unless it has been imperfectly thawed, in which case the central portion may remain frozen after the external layers have begun to cook, and when the latter are thoroughly roasted, the inside may still be found almost raw. Frozen meat loses 10 per cent of its nutritive value in cooking. Such meat has been transported in fresh condition as far as fifty miles inland in the Philippines.