2. Drying.—This is one of the oldest and ,est known of the various processes of preser •ation, and is applied to both animal and vege able products. By this means, beef and fish if many kinds, grapes, figs, apples, peaches, .urrants and many other kinds of fruit and everal vegetables are annually preserved by frying, and are thus rendered suitable for ransportation to distant markets, in conse pence of great reduction in weight and bulk, is well as preservation from decay. The more rapidly the drying process is conducted the bet ter. Drying is conducted in the open air by the rid of the sun's heat, or by artificial means. The curing of fish by !frying constitutes an im portant industry in most northern maritime :ountries, the principal edible fish employed for this purpose being cod and herring, of which large numbers are dried -in the fishing ports of the Atlantic coast north of Cape Cod, and in the British Isles and on the coast of Norway and Sweden. Fish are prepared for drying by the removal of the entrails, slitting them length wise. They are then dried in the open air.
3. Salting is one of the oldest and best-known methods of preserving meat and fish. The most common method of preserving meat, especially pork, is by placing the meat in casks in layers, with salt between. The salt withdraws water from the meat, and the brine thus formed penetrates the fibres of the meat. In Eckart's Munich quick-salting process, pork is impregnated under pressure with a 25 per cent solution of common salt for 24 hours and then smoked. It is claimed that by this process the loss consists, mainly, of only water and a little phosphoric acid, that the meat has a better flavor and that trichinae, if present, are com pletely destroyed. As one of the results of salting meat is the removal of its natural color, it is customary to add a small quantity of salt petre to counteract this effect. According to Lehmann, a small percentage only should be used on account of its harmful effect. A dose of five grams of this salt has caused severe ill ness and eight grams has been known to cause death. The effect upon the human system of the continued use of meat containing saltpetre has not been determined by observation or ex periment.
Influence of Salting upon Bacteria.— For ster's experiments show that the streptococci of erysipelas and many other well-known bacteria can live for weeks and even months in salted meat. The bacilli of tuberculosis retain their virulence for more than two months, and while the bacteria of anthrax perish in less than a day, their spores retain their vitality for a much longer period.
Effect of Salting upon Flesh.— Salted meat is harder and more difficult of digestion than fresh meat. Voit shows by analysis that the
nutritive value of meat is only slightly dimin ished after 14 days' salting. He fotind the per centage loss to be for water 10.4, organic matter 2.1, albumen 1.1, extractives 13.5, phosphoric acid 8.5. The amount of salt taken up by 1,000 grams of fresh meat was 43 grams. Polenske, on the contrary (Jahresbericht Nahr. u. Genuss mittel 1891, p. 40), found that the meat, after being salted for three weeks, lost 7.7 per cent of its nitrogenous constituents, and 34.7 per cent of its phosphoric acid, and after three months and six months the loss was still greater. He therefore concluded that the meat was greatly altered in its nutritive character, and that it could not be used continuously without injurious effects. Salted pork constituted a very import ant part of the food ration of the Union army in the Civil War, and when accompanied with an abundant supply of fresh vegetables, it was considered a wholesome article of food. Ab sence of the latter, however, was often the cause of serious illness. Strobmer gives the preced ing analyses of fresh and salted herring.
This is the salted roe of the stur geon and other fish. It is prepared by washing the roe with salt water, leaving it in the brine for some time, pressing it, again treating it with salt water, passing it through a hair sieve, and finally packing it in salt. The most highly prized is the Astrakhan caviare, which is pre pared at the mouth of the Volga. The follow ing analyses of caviare are compiled from the works of Gobley and of ICOnig: 4. Smoking.— The preservative qualities im parted to meat or fish by smoking are due partly to the drying action of heat, and partly to the antiseptic action of some of the sub stances of which smoke is composed, namely, creosote, formaldehyde and pyroligneous acid. The smoke coagulates the albumen outside of the meat, and forms a protecting envelope. The best woods for the production of smoke for preserving are hickory, beech, birch and poplar, the conifers being unsuitable in consequence of the resin which they contain. There is no loss of nutriment, and Strohmer found that smoked meat is as digestible as fresh meat. Smoking may be conducted in two ways: (1) by slowly smoking the meat for 24 hours at 77° F., or in the case of sausages and fish at 158° F., and then for a short time at 212° F.; (2) the meat may be placed directly in the hot smoke. Prod ucts prepared by the slow process have been found to contain more micro-organisms than those made more rapidly. The smoking should be continuous and not intermittent. A substi tute for smoking largely employed is dipping the meat three times into dilute pyroligneous acid, allowing it to dry off in between.