Chemistry, inorganic and organic : with experiments / by Charles Loudon Bloxam.
- Charles Bloxam
- Date:
- 1875
Licence: Public Domain Mark
Credit: Chemistry, inorganic and organic : with experiments / by Charles Loudon Bloxam. Source: Wellcome Collection.
640/708 page 612
![about half its weight of water, 40 per cent, of the organic constituents of the juice of flesh (albumen excepted), and 10 per cent, of saline matter. Cooking of meat.—A knowledge of the composition of the juice of flesh explains the practice adopted in boiling meat, of immersing it at once in boiling water, instead of placing it in cold water, which is afterwards raised to the boiling point. In the latter case, the water would soak into the meat, and remove the important nutritive matter contained in the juice ; whilst, in the former, the albumen in the external layer of flesh is at once coagulated, and the water is prevented from penetrating to the interior. In making soup, of course, the opposite method should be fol- lowed, the meat being placed in cold water, the temperature of which is gradually raised, so that all the juice of flesh may be extracted, and the muscular fibre and vessels alone left. The object to be attained in the preparation of beef-tea, is the extraction of the whole of the soluble matters from the flesh, to effect which the meat should be minced as finely as possible, soaked for a short time in an equal weight of cold water, and slowly raised to the boiling point, at which it is maintained for a few minutes. The liquid strained from the residual fibrine contains all the constituents of the juice except the albu- men, which has been coagulated. When meat is roasted, the internal portions do not generally attain a sufficiently high temperature to coagulate the albumen of the juice, but the outside is heated far above 212° F. ; so that the meat becomes impregnated to a greater extent with the melted fat, and some of the constituents of the juice in this part suffer a change, which gives rise to the peculiar flavour of roast meat. The brown sapid substance thus pro- duced has been called osmazome* but nothing is really known of its true nature. In salting meat for the purpose of preserving it, a great deal of the juice of flesh oozes out, and a proportionate loss of nutritive matter is sus- tained. 435. Gelatine.—Wlien portions of m.eat, containing cartilages (gristle) or tendons, are boiled for some time with water, the liquid so obtained sets to a jelly on cooling. 'I'his is due to the presence of gelatine or chondrine, or both—substances so nearly resembling each other, that they were long confounded under the name of gelatine. The difference in their origin is that gelatine is obtained by the action of water at a high tem- perature on skin, membrane, and b.one,t whilst chondrine is obtained in the same way from the cartilages. In their properties there is very little difference, the most important being that a solution of chondrine is pre- cipitated by acetic acid, by alum, and by acetate of lead, which do not precipitate gelatine. In composition there is a considerable difference between gelatine and choudi'ine, the latter containing considerably more oxygen and less nitro- gen. The simplest formults which have been assigned to them are— Gelatine, . . . C^iIlQy]Srj.,Oie Chondrine, . . . CggHgNgOm; but they both contain phosphates of lime and magnesia in a very intimate state of association. The characteristic properties of gelatine are the tendency of its solution * From o(T|iiji, odowr; ^(u/jlos, soup. + The animal matter of bone apiiears to t«3 isomeric with golatijie, and is called osseitie.](https://iiif.wellcomecollection.org/image/b21497382_0640.jp2/full/800%2C/0/default.jpg)
