Popular Science Monthly/Volume 25/October 1884/The Chemistry of Cookery XVI
|THE CHEMISTRY OF COOKERY.|
A CORRESPONDENT from Hereford refers to the concluding paragraph of my last paper "as too valuable to let slip, without making practical use of it," and, accordingly, asks for further information concerning the salts that should be contained in our food, and "in what other form can a poor mortal obtain them."
As the question may have presented itself to many other readers, I will answer it here, especially as I can speak from practical experience of the miseries that may be escaped by understanding and applying it. I inherit what is called a "lithic-acid diathesis." My father and his brother were martyrs to rheumatic gout, and died early in consequence. I had a premonitory attack of gout at the age of twenty-five, and other warning symptoms at other times, but have kept the enemy at bay during nearly forty years by simply understanding that this lithic acid (stony acid) combines with potash, forming thus a soluble salt, which is safely excreted. Otherwise it is deposited here or there, producing gout, rheumatism, stone, gravel, and other dreadfully painful diseases, which are practically incurable when the deposit is fairly established. By effecting the above-named combination in the blood, the deposition is prevented.
The potash required for the purpose exists in several conditions: First, in its uncombined state as caustic potash. This is poison, for the simple reason that it combines so vigorously with organic matter that it would decompose the digestive organs themselves if presented to them. The lower carbonate is less caustic, the bicarbonate nearly, but not quite, neutral. Even this, however, should not be taken as food, because it is capable of combining with the acid constituents of the gastric juice.
The proper compounds to be used are those which correspond to the salts existing in the juices of vegetables and flesh—viz., compounds of potash with organic acids, such as tartaric acid, which forms the potash salt of the grape, such as citric acid, with which potash is combined in lemons and oranges; malic acid, with which it is combined in apples and many other fruits; the natural acids of vegetables generally; lactic acid in milk, etc.
All these acids, and many others of similar origin, are composed of carbon, oxygen, and hydrogen, held together with such feeble affinity that they are easily dissociated or decomposed by heat. This may be shown by heating some cream of tartar or tartaric acid on a strip of metal or glass. It will become carbonized to a cinder, like other organic matter. If the heat is raised sufficiently, this cinder will all burn away to carbonic acid and water in the case of the pure acid, or will leave carbonate of potash in the case of cream of tartar or other potash salt.
Unless I am mistaken, this represents violently what occurs gradually and mildly in the human body, which is in a continuous state of slow combustion so long as it is alive. The organic acids of the potash salts suffer slow combustion, give off their excess of carbonic acid and water to be breathed out, evaporated, and ejected, leaving behind their potash, which combines with the otherwise stony lithic-acid tormentor just when and where he comes into separate existence by the organic actions which effect the above-described slow combustion.
If we take potash in combination with a mineral acid, such as the sulphuric, nitric, or hydrochloric, no such decomposition is possible; the bonds uniting the elements of the mineral acid are too strong to be sundered by the mild chemistry of the living body, and the mineral acid, if separated from its potash base, would be most mischievous, as it precipitates the lithic acid in its worst form.
For this reason, all free mineral acids are poisons to those who have a lithic-acid diathesis; they may even create it where it did not previously exist. Hence the iniquity of cheapening the manufacture of lemonade, ginger-beer, etc., by using dilute sulphuric or hydrochloric acid as a substitute for citric or tartaric acid. I shall presently come to the cookery of wines, and have something to say about the mineral acids used in producing the choicer qualities of some very "dry," high-priced samples that, according to my view of the subject, have caused the operations of lithotomy and lithotrity to be included among the luxuries of the rich.
It should be understood that, when I recommended the use of bicarbonate of potass for the solution of casein, all these principles were kept in view, including the objection to the bicarbonate itself. In the case of the cheese the quantity recommended was based on an estimate of the quantity of lactic acid existing in the cheese and capable of leaving the casein to go over to the potash. In the case of the peas the quantity is difficult to estimate, owing to its variability. The more correct determination of such quantities is among the objects of further research, and which I alluded to in my last.
Speaking generally it is not to the laboratory of the chemist that we should go for our potash salts, but to the laboratory of nature, and more especially to that of the vegetable kingdom. They exist in the green parts of all vegetables. This is illustrated by the manufacture of commercial potash from the ashes of the twigs and leaves of timber-trees. The more succulent the vegetable the greater the quantity of potash it contains, though there are some minor exceptions to this. As I have already stated, we extract and waste a considerable proportion of these salts when we boil vegetables and throw away the potage, which our wiser and more thrifty neighbors add to their every-day ménu. When we eat raw vegetables, as in salads, we obtain all their potash.
Fruits generally contain important quantities of potash salts, and it is upon these especially that the possible victims of lithic acid should rely. Lemons and grapes contain them most abundantly. Those who can not afford to buy these as articles of daily food may use cream of tartar, which, when genuine, is the natural salt of the grape, thrown down in the manner I shall describe when on the subject of the cookery of wines.
At the risk of being accused of presumption, I must here protest, as a chemist, against one of "the fallacies of the faculty," or of certain members of the faculty, viz., that of indiscriminately prohibiting to gouty and rheumatic patients the use of acids or anything having an acid taste.
This has probably arisen from experience of the fact that mineral acids do serious mischief, and that alkaline carbonate of potash affords relief. The difference between the organic acids, which are decomposed in the manner I have described, and the fixed composition of the mineral acids does not appear to have been sufficiently studied by those who prohibit fruit and vegetables on account of their acidity. It must never be forgotten that nearly all the organic compounds of potash, as they exist in vegetables and fruit, are acid. It may be desirable, in some cases, to add a little bicarbonate of potash to neutralize this excess of acid and increase the potash-supply. I have found it advantageous to throw a half-saltspoonful of this into a tumbler of water containing the juice of a lemon, and have even added to it stewed or baked rhubarb and gooseberries. In these it froths like whipped cream, and diminishes the demand for sugar, an excess of which appears to be mischievous to those who require much potash.
I must conclude this sermon on the potash text by adding that it is quite possible to take an excess of this solvent. Such excess is depressing; its action is what is called "lowering." I will not venture upon an explanation of the rationale of this lowering, or discuss the question of whether or not the blood is made watery, as sometimes stated.
Intimately connected with this part of my subject is another vegetable principle that I have not yet named. This is vegetable jelly, or pectin, the jelly of fruits, of turnips, carrots, parsnips, etc. Fremy has named it pectose. It is so little changed by cookery that I need say little about it beyond stating the fact that an acid may be separated from it which has been named pectic acid, the properties and artificial compounds of which appear to me to suggest the theory that the natural jelly of fruits largely consists of pectites of potash or soda or lime. We all know the appearance and flavor of currant-jelly, apple-jelly, etc., which are composed of natural vegetable jelly plus sugar.
?The separation of these jellies is an operation of cookery, and one that deserves more attention than it receives. I shall never forget the rahat lakoum which I once had the privilege of eating in the kitchen of the seraglio of Stamboul, in the absence at the summer palace of the sultana and the other ladies for whom it was prepared. Its basis was the pure pectose of many fruits, the inspissated juices of grapes, peaches, pineapples, and I know not what others. The sherbet was similar, but liquid. Well may they obey the Prophet and abstain from the grosser concoctions that we call wine when such ambrosial nectar as this is supplied in its place! It is to imperial tokay as tokay is to table-beer!
The "lumps of delight" sold by our confectioners are imitations made of flavored gelatine. Similar substitutes are sold in Constantinople. The same as regards the sherbet.
I conclude this part of my subject by re-echoing Mr. Gladstone's advocacy of the extension of fruit-culture. We shamefully neglect the best of all food, in eating and drinking so little fruit. As regards cooked fruit, I say jam for the million, jelly for the luxurious, and juice for all. With these in abundance, the abolition of alcohol will follow as a necessary result of natural nausea.
I must not leave the subject of vegetable cookery without describing Count Rumford's achievements in feeding the paupers, rogues, and vagabonds of Munich. An account of this is the more desirable, from the fact that the "soup" which formed the basis of his dietary is still misunderstood in this country, for reasons that I shall presently state.
After reorganizing the Bavarian army, not only as regards military discipline, but in the feeding, clothing, education, and useful employment of the men, in order to make them good citizens as well as good soldiers, he attacked a still more difficult problem—that of removing from Bavaria the scandal and burden of the hordes of beggars and thieves which had become intolerable. He tells us that "the number of itinerant beggars of both sexes, and all ages, as well foreigners as natives, who strolled about the country in all directions, levying contributions from the industrious inhabitants, stealing and robbing, and leading a life of indolence and most shameless debauchery, was quite incredible"; and further, that "these detestable vermin swarmed everywhere, and not only their impudence and clamorous importunity were without any bounds, but they had recourse to the most diabolical acts, and most horrid crimes, in the prosecution of their infamous trade. Young children were stolen from their parents by these wretches, and their eyes put out, or their tender limbs broken and distorted, in order, by exposing them thus maimed, to excite the pity and commiseration of the public." He gives further particulars of their trading upon the misery of their own children, and their organization to obtain alms by systematic intimidation. Previous attempts to cure the evil had failed, and the public had lost all faith in further projects, and therefore no support was to be expected for Rumford's scheme. "Aware of this," he says, "I took my measures accordingly. To convince the public that the scheme was feasible, I determined first, by a great exertion, to carry it into complete execution, and then to ask them to support it."
He describes the military organization by which he distributed the army throughout the country districts to capture all the strolling provincial beggars, and how, on January 1, 1790, he bagged all the beggars of Munich in less than an hour by means of a well-organized civil and military battue, the New-Year's-Day being the great festival when all the beggars went abroad to enforce their customary black-mail upon the industrious section of the population. Though very interesting, I must not enter upon these details, but can not help stepping a little aside from my proper subject to quote his weighty words on the ethical principles upon which he proceeded. He says that "with persons of this description, it is easy to be conceived that precepts, admonitions, and punishments would be of little avail. But, where precepts fail, habits may sometimes be successful. To make vicious and abandoned people happy, it has generally been supposed necessary, first, to make them virtuous. But why not reverse this order? Why not make them first happy and then virtuous? If happiness and virtue be inseparable, the end will as certainly be attained by one method as by the other; and it is most undoubtedly much easier to contribute to the happiness and comfort of persons in a state of poverty and misery than, by admonitions and punishments, to improve their morals."
He applied these principles to his miserable material with complete success, and referring to the result exclaims, "Would to God that my success might encourage others to follow my example!" Further examination of his proceedings shows that, in order to follow such example, a knowledge of first principles and a determination to carry them out in bold defiance of vulgar ignorance, general prejudice, and polite sneering, are necessary.
Having captured the beggars thus cleverly, he proceeded to carry out the above-stated principle, by taking them to a large building already prepared, and where "everything was done that could be devised to make them really comfortable" The first condition of such comfort, he maintains, is cleanliness, and his dissertation on this, though written so long ago, might be inscribed in letters of gold over the portals of our Health Exhibition of to-day.
Describing how he carried out his principles, he says of the prisoners thus captured: "Most of them had been used to living in the most miserable hovels, in the midst of vermin and every kind of filthiness, or to sleep in the streets, and under the hedges, half naked and exposed to all the inclemencies of the seasons. A large and commodious building, fitted up in the neatest and most comfortable manner, was now provided for their reception. In this agreeable retreat they found spacious and elegant apartments, kept with the most scrupulous neatness; well warmed in winter, and well lighted; a good, warm dinner every day, gratis, cooked and served up with all possible attention to order and cleanliness; materials and utensils for those that were able to work; masters gratis for those who required instruction; the most generous pay, in money, for all the labor performed; and the kindest usage from every person, from the highest to the lowest, belonging to the establishment. Here in this asylum for the indigent and unfortunate no ill-usage, no harsh language is permitted. During five years that the establishment has existed, not a blow has been given to any one, not even to a child by his instructor."
This appears like the very expensive scheme of a benevolent Utopian; but, to set my readers at rest on this point, I will anticipate a little by stating that, although at first some expense was incurred, all this was finally repaid, and, at the end of six years, there remained a net profit of one hundred thousand florins "after expenses of every kind, salaries, wages, repairs, etc., had been deducted."
I must not dwell upon his devices for gradually inveigling the lazy creatures into habits of industry, for he understood human nature too well to adopt the jailer's theory, which assumes that every able-bodied man can do a day's work daily, in spite of previous habits. Rumford's patients became industrious ultimately, but were not made so at once.
This development of industry was one of the elements of financial and moral success, and the next in importance was the economy of the commissariat, which depended on Rumford's skillful cookery of the cheapest viands, rendering them digestible, nutritious, and palatable. Had he adopted the dietary of an English workhouse or an English prison, his financial success would have been impossible, and his patients would have been no better fed, nor better able to work.
The staple food was what he calls a "soup," but I find, on following out his instructions for making it, that I obtain a porridge rather than a soup. He made many experiments, and says: "I constantly found that the richness or quality of a soup depended more upon a proper choice of the ingredients, and a proper management of the fire in the combination of these ingredients, than upon the quantity of solid nutritious matter employed; much more upon the art and skill of the cook than upon the sum laid out in the market."
Our vegetarian friends will be interested in learning that at first he used meat in the soup provided for the beggars, but gradually omitted it, and the change was unnoticed by those who ate, and no difference was observable as regards its nutritive value.
In 1790 little, or rather nothing, was known of the chemistry of food. Oxygen had been discovered only sixteen years before, and chemical analysis, as now understood, was an unknown art. In spite of this, Rumford selected as the basis of his soup just that proximate element which we now know to contain, bulk for bulk, more nutritive matter than any other that exists either in the animal or vegetable kingdom, viz., casein. He not only selected this, but he combined it with those other constituents of food which our highest refinements of modern practical chemistry and physiology have proved to be exactly what are required to supplement the casein and constitute a complete dietary. By selecting the cheapest form of casein and the cheapest sources of the other constituents, he succeeded in supplying the beggars with good hot dinners daily at the cost of one halfpenny each. The cost of the mess for the Bavarian soldiers under his command was rather more, viz., twopence daily, three farthings of this being devoted to pure luxuries, such as beer, etc. The details of the means by which he achieved these notable results will be stated in my next.