Culinary Chemistry / The Scientific Principles of Cookery, with Concise Instructions for Preparing Good and Wholesome Pickles, Vinegar, Conserves, Fruit Jellies, Marmalades, and Various Other Alimentary Substances Employed in Domestic Economy, with Observations on the Chemical Constitution and Nutritive Qualities of Different Kinds of Food.

by Friedrich Christian Accum

Let the substance to be preserved be first par-boiled, or rather somewhat more, the bones of the meat being previously removed. Put the meat into a tin cylinder, fill up the vessel with the broth, and then solder on the lid, furnished with a small hole. When this has been done, let the tin vessel, thus prepared, be placed in water and heated to the boiling point to complete the remainder of the cooking of the meat. The hole in the lid is now closed perfectly, by soldering, whilst the air is rushing out.

The vessel is then allowed to cool, and from the diminution of volume in the contents, in consequence of the reduction of temperature, both ends of the cylinder are pressed inwards and become concave. The tin cases, thus hermetically sealed, are exposed in a test-chamber for at least a month, to a temperature above what they are ever likely to encounter; from 90° to 110° Fahrenheit. If the process has failed, putrefaction takes place, and gas is evolved, which in process of time will bulge out both ends of the case, so as to render them convex instead of concave. But the contents of whatever cases stand this test, will infallibly keep perfectly sweet and good in any climate, and for any length of time. If there was any taint about the meat when put up, it inevitably ferments, and is detected in the proving process.

All kinds of animal food may be preserved in this way—beef, mutton, veal, and poultry, either boiled or roasted. The testimonies in favour of the success of the process are of the most unexceptionable kind. At Messrs. Donkin and Gamble’s establishment the meat is put up in canisters of from 4 lbs. to 20 lbs. weight each. It is charged from 1s. 8d. to 3s. a pound; roast higher than boiled, and veal dearer than mutton or beef. The weight of the canister is deducted, and nothing is charged for the canisters; and it should be observed, that these provisions being cooked, and without bone, render them equivalent to double the weight of meat in the raw state; for it is certain, that the waste in cooking, together with the weight of bone, are about one half.

Captain Neish took a quantity of provision, thus prepared, to India, not one canister spoiled; and one which he brought home contained beef in the highest state of preservation after two years, and having been carried upwards of 35,000 miles in the warmest climates.

The commissioners for victualling the navy also examined some, nearly four years old, which had been in the Mediterranean and Quebec, and found it as sound, sweet, and fresh, as if it had been only yesterday boiled. We are enabled to add the testimony of that distinguished navigator, captain Basil Hall, who has liberally communicated to us the result of his personal experience and observation, which is as follows:—“I can answer for the perfect preservation of a great number of cases which were in my possession during the voyage to China. I had 88l. worth, and not one failure. At that time milk was preserved in bottles corked; but tin cases have been substituted with very great effect, as I have myself tried. It is really astonishing how excellent the milk is; and, indeed, every thing preserved in this way is good.”

“You must, on examining the list of prices, bear in mind, that meat thus preserved eats nothing, nor drinks—is not apt to get the rot, or to die—does not tumble over-board, nor get its legs broken, or its flesh wore off its bones, by knocking about the decks of a ship in bad weather—it takes no care in the keeping—it is always ready—may be eat cold or hot—and thus enables you to toss into a boat in a minute, as many days’ cooked provisions as you choose—it is not exposed to the vicissitudes of markets, nor is it scourged up to a monstrous price (as at St. Helena), because there is no alternative. Besides these advantages, it enables one to indulge in a number of luxuries, which no care or expence could procure.”

In this preservative process is displayed a singular and important fact with regard to the agency of oxygen in putrefaction. The tin canisters being closed during the exposure to heat, must necessarily contain with the included matter some portion of air; and if heat were not applied, or even if applied imperfectly, putrefaction would take place. This proves that the effect of the high temperature is to produce some kind of combination of the oxygen of the air with the animal or included matter, not leading to putrefaction, or even counter-acting it, while by this combination it is effectually removed. The air accordingly, where the process is successful, is deprived of oxygen; but if the heat were not sufficiently prolonged, and by far the greatest part of the air in the vessel not exhausted, putrefaction soon comes on. From experiments that have been made on this mode of preserving alimentary substances, it has been proved, that if the vessels were opened only for a short time and again closed, without heat being applied, the inclosed substances soon putrefied: as they did also from mere exposure to the air. But if, after having been exposed even for an hour or two, they were re-placed, the vessels again treated as before, and then the due degree of heat applied, they could be preserved as at first. And this repeated exposure to the air, and removal of its operation by heating, it appears from Gay Lussac’s experiments, can be renewed a number of times. Nay, by occasional exposure to the heat of boiling water, without the exclusion of the air, he found the exemption from putrefaction to be attained.

The theory of these effects is not very apparent. Gay Lussac supposes, that the oxygen may combine with that principle analogous to gluten, which excites fermentation, and which may equally excite putrefaction; that this by a kind of coagulation is separated by heat, and thus rendered inert; and that it is only that part of it which has suffered oxygenation which is capable of this coagulation; it is thus removed, while the exclusion of oxygen prevents the putrefaction from taking place, which would otherwise be excited by the remainder. But this is rather hypothetical and unsatisfactory.

PRESERVATION OF MEAT BY POTTING.

The process of potting consists in reducing cooked animal substances to a pulp, by beating the meat in a mortar, and incorporating the mass with a portion of salt and spices. The pulp is then put into a jar, and covered with a thick coat of melted butter or lard, to prevent the contact of air; and the surface is further protected with a bladder-skin tied over the mouth of the jar. The muscular part of meat is best suited for potting, and the quantity of salt and spices ought to be rather liberal.