The Chemistry of Cookery — The Cookery of Wine Part 1

THE COOKERY OF WINE.

IN an unguarded moment I promised to include the above in this work, and will do the best I can to fulfil the rash promise; but the utmost result of this effort can only be a contribution to a subject which is too profoundly mysterious to be fully grasped by any intellect that is not sufficiently clairvoyant to penetrate paving-stones, and see through them to the interiors of the closely-tiled cellars wherein the mysteries are manipulated.

I will first define what I mean by the cookery of wine.

Grape juice in its unfermented state may be described as ‘raw wine,’ or this name may be applied to the juice after fermentation.

I apply it in the latter sense, and shall use it as describing grape juice which has been spontaneously and recently fermented without the addition of any foreign materials, or altered by keeping, or heating, or any other process beyond fermentation.

All such processes and admixture which affect any chemical changes on the raw material I shall describe as cookery, and the result as cooked wine.

When I refer to wine made from other juice than that of the grape it will be named specifically.

At the outset a fallacy, very prevalent in this country, should be controverted.

The high prices charged for the cooked material sold to Englishmen has led to absurdly exaggerated notions of the original value of wine.

I am quite safe in stating that the average market value of rich wine in its raw state, in countries where the grape grows luxuriantly, and where, in consequence, the average quality of the wine is the best, does not exceed sixpence per gallon, or one penny per bottle.

I speak now of the newly-made wine.

Allowing another sixpence per gallon for barrelling and storage, the value of the commodity in portable form becomes twopence per bottle.

I am not speaking of thin, poor wines, produced by a second or third pressing of the grapes, but of the best and richest quality, and, of course, I do not include the fancy wines—those produced in certain vineyards of celebrated châteaux—that are superstitiously venerated by those easily-deluded people who suppose themselves to be connoisseurs of choice wines.

I

refer to ninety-nine per cent.

of the _rich_ wines that actually come into the market.

Wines made from grapes grown in unfavourable climates naturally cost more in proportion to the poorness of the yield.

As some of my readers may be inclined to question this estimate of average cost, a few illustrative facts may be named.

In Sicily and Calabria I usually paid at the roadside or village ‘osterias’ an equivalent to one halfpenny for a glass or tumbler holding nearly half a pint of common wine, thin, but genuine.

This was at the rate of less than one shilling per gallon, or twopence per bottle, and included the cost of barrelling, storage, and innkeeper’s profit on retailing.

In the luxuriant wine-growing regions of Spain, a traveller halting at a railway refreshment station and buying one of the sausage sandwiches that there prevail, is allowed to help himself to wine to drink on the spot without charge, but if he fills his flask to carry away he is subjected to an extra charge of one halfpenny.

It is well known to all concerned that at vintage-time of fairly good seasons, in all countries where the grape grows freely, a good empty cask is worth more than the new wine it contains when filled; that much wine is wasted from lack of vessels, and anybody sending two good empty casks to a vigneron can have one of them filled in exchange for the other.

Those who desire further illustrations and verification should ask their friends—_outside of the trade_—who have travelled in Southern wine countries, and know the language and something more of the country than is to be learned by being simply transferred from one hotel to another under the guidance of couriers, ciceroni, valets de place, &c. Thus the five shillings paid for a bottle of rich port is made up of one penny for the original wine, one penny more for cost of storage, &c. , about sixpence for duty and carriage to this country, and twopence for bottling, making tenpence altogether; the remaining four shillings and twopence is paid for cookery and wine-merchant’s profits.

Under cookery I include those changes which may be obtained by simply exposing the wine to the action of the temperature of an ordinary cellar, or the higher temperature of ‘Pasteuring,’ to be presently described.

In the youthful days of chemistry the first of these methods of cookery was the only one available, and wine was kept by wine-merchants with purely commercial intent for a considerable number of years.

A little reflection will show that this simple and original cookery was very expensive, sufficiently so to legitimately explain the rise in market value from tenpence to five shillings or more per bottle.

Wine-merchants require a respectable profit on the capital they invest in their business—at least ten per cent.

per annum on the prime cost of the wine laid down.

Then there is the rental of cellars and offices, the establishment expenses—such as wages, sampling, sending out, advertising, losses by bad debts, &c. —to be added.

The capital lying dead in the cellar demands compound interest.

At ten per cent.

the principal doubles in about seven and one-third years.

Calling it seven years, to allow very meagrely for establishment expenses, we get the following result: £ s. d.

When 7 years old the tenpenny wine is worth 0 1 8 per bottle.

” 14 ” ” ” 0 3 4 ” ” 21 ” ” ” 0 6 8 ” ” 28 ” ” ” 0 13 4 ” ” 35 ” ” ” 1 6 8 ” Here, then, we have a fair commercial explanation of the high prices of old-fashioned old wines; or of what I may _now_ call the traditional value of wine.

Of course, this is less when a man lays down his own wine in his own cellar, in obedience to the maxim, ‘Lay down good port in the days of your youth, and when you are old your friends will not forsake you.

’ He may be satisfied with a much smaller rate of interest than the man engaged in business fairly demands.

Still, when wine thus aged was thrown into the market, it competed with commercially cellared wine, and obtained remarkable prices, especially as it has a special value for ‘blending’ purposes, _i.

e. _ for mixing with newer wines and infecting them with its own senility.

But why do I say that _now_ such values are traditional?

Simply because the progress of chemistry has shown us how the changes resulting from years of cellarage may be effected by scientific cookery in a few hours or days.

We are indebted to Pasteur for the most legitimate—I might say the only legitimate—method of doing this.

The process is accordingly called ‘Pasteuring.

’ It consists in simply heating the wine to the temperature of 60° C. = 140° Fahr.

, the temperature at which, as will be remembered, the visible changes in the cookery of animal food commences.

It is worthy of note that this is also the exact temperature at which diastase acts most powerfully in converting starch into dextrin.

Pasteuring is a process demanding considerable skill; no portion of the wine during its cookery must be raised above 140°, yet all must reach it; nor must it be exposed to the air.

The apparatus designed by Rossignol is one of the best suited for this purpose.

It is a large metallic vat or boiler with air-tight cover and a false bottom, from which rises a trumpet-shaped tube through the middle of the vat, and passing through an air-tight fitting in the cover.

The chamber formed by the false bottom is filled with water by means of this tube, the object being to prevent the wine at the lower part from being heated directly by the fire which is below the water chamber.

A thermometer is also inserted air-tight in the lid, with its bulb half-way down the vat.

To allow for expansion a tube is similarly fitted into the lid.

This is bent syphon-like, and its lower end dipped into a flask containing wine or water, so that air or vapour may escape and bubble through, but none enter.

Even in drawing off from the vat the wine is not allowed to flow through the air, but is conveyed by a pipe which bends down, and dips to the bottom of the barrel.

The apparatus is bulky and expensive.

If heated with exposure to air, the wine acquires a flavour easily recognised as the ‘_goût de cuit_,’ or flavour of cooking.

When Pasteur’s method is properly conducted the only changes effected are those which would be otherwise produced by age.

I have heard of many failures made by English wine-merchants in their attempts at Pasteuring, and am not at all surprised, seeing how secretly and clumsily these attempts have been made.

The changes thus produced are somewhat obscure.

One effect is probably that which more decidedly occurs in the maturing of whisky and other spirits distilled from grain, viz.

the reduction of the proportion of amylic alcohol or fusel oil, which, although less abundantly produced in the fermentation of grape juice than in grain or potato spirit, is formed in varying quantities.

Caproic alcohol and caprylic alcohol are also produced by the fermentation of grape juice or the ‘marc’ of grapes—_i.

e. _ the mixture of the whole juice and the skins.

These are acrid, ill-flavoured spirits, more conducive to headache than the ethylic alcohol, which is proper spirit of good wine.

Every wine-drinker knows that the amount of headache obtainable from a given quantity of wine, or a given outlay of cash, varies with the sample, and this variation appears to be due to these supplementary alcohols or ethers.

Another change appears to be the formation of ethers having choice flavours and bouquets; _œnanthic ether_, or the ether of wine, is the most important of these, and it is probably formed by the action of the natural acid salts of the wine upon its alcohol.

Johnston says: ‘So powerful is the odour of this substance, however, that few wines contain more than one forty-thousandth part of their bulk of it.

Yet it is always present, can always be recognised by its smell, and is one of the general characteristics of all grape wines.

’ This ether is stated to be the basis of _Hungarian wine oil_, which, according to the same authority, has been sold for flavouring brandy at the rate of sixty-nine dollars per pound.

I am surprised that up to the present time it has not been cheaply produced in large quantities.

Chemical problems that appear far more difficult have been practically solved.

The paternal tenderness with which wine is regarded, both by its producers and consumers, is amusing.

They speak of it as being ‘sick,’ describe its ‘diseases,’ and their remedies as though it were a sentient being; and these diseases, like our own, are now attributed to bacilli, bacteria, or other microbia.

Pasteur, who has worked out this question of the origin of diseases in wine as he is so well known to have done in animals, recommends (in papers read before the French Academy in May and August 1865), that these microbia be ‘killed’ by filling the bottles close up to the cork, which is thrust in just with sufficient firmness to allow the wine on expanding to force it out a little, but not entirely, thus preventing any air from entering the bottle.

The bottles are then placed in a chamber heated to temperatures ranging from 45° to 100° C. (113° to 212° Fahr.

), where they remain for an hour or two.

They are then set aside, allowed to cool, and the cork driven in.

It is said that this treatment kills the microbia, gives to the wine an increased bouquet and improved colour—in fact, ages it considerably.

Both old and new wines may be thus treated.

I simply state this on the authority of Pasteur, having made no direct experiments or observations on these diseases, which he describes as resulting in acetification, ropiness, bitterness, and decay or decomposition.

There is, however, another kind of sickness which I have studied, both experimentally and theoretically.

I refer to the temporary sickness which sometimes occurs to rich wines when they are moved from one cellar to another, and to light wines when newly exported from their native climate to our own.

Genuine wines are the most subject to such sickness;—the natural, unsophisticated wines, those that have not been subjected to ‘fortification,’ to ‘vinage,’ to ‘plastering,’ ‘sulphuring,’ &c. —processes of cookery to be presently described.

This sickness shows itself by the wine becoming turbid, or opalescent, then throwing down either a crust or a loose, troublesome sediment.

Those of my readers who are sufficiently interested in this subject to care to study it practically should make the following experiment: Dissolve in distilled water, or, better, in water slightly acidulated with hydrochloric acid, as much cream of tartar as will saturate it.

This is best done by heating the water, agitating an excess of cream of tartar in it, then allowing the water to cool, the excess of salt to subside, and pouring off the clear solution.

Now add to this solution, while quite clear and bright, a little clear brandy, whisky, or other spirit, and mix them by shaking.

The solution will become ‘sick,’ like the wine.

Why is this?

It depends upon the fact that the bitartrate of potash, or cream of tartar, is soluble to some extent in water, but almost insoluble in alcohol.

In a mixture of alcohol and water its solubility is intermediate—the more alcohol the smaller the quantity that can be held in solution (hydrochloric and most other acids, excepting tartaric, increase its solubility in water).

Thus, if we have a saturated solution of this salt either in pure water or acidulated water, or wine, the addition of alcohol throws some of it down in solid form, and this makes the solution sick or turbid.

When pure water or acidulated water is used, as in the above-described experiment, crystals of the salt are freely formed, and fall down readily; but with a complex liquid like wine, containing saccharine and mucilaginous matter, the precipitation takes place very slowly; the particles are excessively minute, become entangled with the mucilage, &c. , and thus remain suspended for a long time, maintaining the turbidity accordingly.

Now, this bitartrate of potash is the characteristic natural salt of the grape, and its unfermented juice is saturated with it.

As fermentation proceeds, and the sugar of the grape-juice is converted into alcohol, the capacity of the juice for holding the salt in solution diminishes, and it is gradually thrown down.

But it does not fall alone.

It carries with it some of the colouring and extractive matter of the grape-juice.

This precipitate, in its crude state called _argol_, or _roher Weinstein_, is the source from which we obtain the tartaric acid of commerce, the cream of tartar, and other salts of tartaric acid.

Now let us suppose that we have a natural, unsophisticated wine.

It is evident that it is saturated with the tartrate, since only so much argol was thrown down during fermentation as it was unable to retain.

It is further evident that if such a wine has not been exhaustively fermented, _i.

e. _ if it still contains some of the original grape-sugar, and if any further fermentation of this sugar takes place, the capacity of the mixture for holding the tartrate in solution becomes diminished, and a further precipitation must occur.

This precipitation will come down very slowly, will consist not merely of pure crystals of cream of tartar, but of minute particles carrying with it some colouring matter, extractives, &c. , and thus spoiling the brilliancy of the wine, making it more or less turbid.

But this is not all.

Boiling water dissolves ⅙th of its weight of cream of tartar, cold water only 1/180th, and, at intermediate temperatures, intermediate quantities.

Therefore, if we lower the temperature of a saturated solution, precipitation occurs.

Hence, the sickening of wine due to change of cellars or change of climate, even when no further fermentation occurs.

The lighter the wine, _i.

e. _ the less alcohol it contains naturally, the more tartrate it contains, and the greater the liability to this source of sickness.

This, then, is the temporary sickness to which I have referred.

I

have proved the truth of this theory by filtering such sickened wine through laboratory filtering paper, thereby rendering it transparent, and obtaining on the paper all the guilty disturbing matter.

I found it to be a kind of argol, but containing a much larger proportion of extractive and colouring matter, and a smaller proportion of tartrate than the argol of commerce.

I operated upon rich new Catalan wine.

This brings me at once to the source or origin of a sort of wine-cookery by no means so legitimate as the Pasteuring already described, as it frequently amounts to serious adulteration.

The wine-merchants are here the victims of their customers, who demand an amount of transparency that is simply impossible as a permanent condition of unsophisticated grape-wine.

To anybody who has any knowledge of the chemistry of wine, nothing can be more ludicrous than the antics of the pretending connoisseur of wine who holds his glass up to the light, shuts one eye (even at the stage before double vision commences), and admires the brilliancy of the liquid, this very brilliancy being, in nineteen samples out of twenty, the evidence of adulteration, cookery, or sophistication of some kind.

Genuine wine made from pure grape-juice without chemical manipulation is a liquid that is never reliably clear, for the reasons above stated.

Partial precipitation, sufficient to produce opalescence, is continually taking place, and therefore the unnatural brilliancy demanded is obtained by substituting the natural and wholesome tartrate by salts of mineral acids, and even by the free mineral acid itself.

At one time I deemed this latter adulteration impossible, but have been convinced by direct examination of samples of _high-priced_ (mark this, not _cheap_) dry sherries that they contained free sulphuric and sulphurous acid.

The action of this free mineral acid on the wine will be understood by what I have already explained concerning the solubility of the bitartrate of potash.

This solubility is greatly increased by a little of such acid, and therefore the transparency of the wine is by such addition rendered stable, unaffected by changes of temperature.

But what is the effect of such free mineral acid on the drinker of the wine?

If he is in any degree pre-disposed to gout, rheumatism, stone, or any of the lithic acid diseases, his life is sacrificed, with preceding tortures of the most horrible kind.

It has been stated, and probably with truth, that the late Emperor Napoleon III.

drank dry sherry, and was a martyr of this kind.

I repeat emphatically that, generally speaking, high-priced dry sherries are far worse than cheap Marsala, both as regards the quantity they contain of sulphates and free acid.

Anybody who doubts this may convince himself by simply purchasing a little chloride of barium, dissolving it in distilled water, and adding to the sample of wine to be tested a few drops of this solution.

Pure wine, containing its full supply of natural tartrate, will become cloudy to a small extent, and gradually.

A small precipitate will be formed by the tartrate.

The wine that contains either free sulphuric acid or any of its compounds will yield _immediately_ a copious white precipitate like chalk, but much more dense.

This is sulphate of baryta.

The experiment may be made in a common wine-glass, but better in a cylindrical test-tube, as, by using in this a fixed quantity in each experiment, a rough notion of the relative quantity of sulphate may be formed by the depth of the white layer after all has come down.

To determine this _accurately_, the wine, after applying the test, should be filtered through proper filtering paper, and the precipitate and paper burnt in a platinum or porcelain crucible and then weighed;

but this demands apparatus not always available, and some technical skill.

The simple demonstration of the copious precipitation is instructive, and those of my readers who are practical chemists, but have not yet applied this test to such wines, will be astonished, as I was, at the amount of precipitation.

I may add that my first experience was upon a sample of dry sherry, brought to me by a friend who bought his wine of a respectable wine-merchant, and paid a high price for it, but found that it disagreed with him; it contained an alarming quantity of free sulphuric acid.

Since that I have tested scores of samples, some of the finest in the market, sent to me by a conscientious importer as the best he could obtain, and these contained sulphate of potash instead of bitartrate.

My friend, the sherry-merchant, could not account for it, though he was most anxious to do so.

This was about three years ago.

By dint of inquiry and cross-examination of experts in the wine trade, I have, I believe, discovered the origin of the sulphate of potash that is contained in the samples that the British wine-merchant sells as he buys, and conscientiously believes to be pure.

At first I hunted up all the information I could obtain from books concerning the manufacture of sherry; learned that the grapes are usually sprinkled with a little powdered sulphur as they are placed in the vats prior to stamping.

The quantity thus added, however, is quite insufficient to account for the sulphur compounds in the samples of wine I examined.

Another source is described in the books—that from sulphuring the casks.

This process consists simply of burning sulphur inside a partially-filled or empty cask, until the exhaustion of free oxygen and its replacement by sulphurous acid renders further combustion impossible.

The cask is then filled with the wine.

This would add a little of sulphurous acid, but still not sufficient.

Then comes the ‘plastering,’ or intentional addition of gypsum (plaster of Paris).

This, if largely carried out, is sufficient to explain the complete conversion of the natural tartrates into sulphates of potash, and such plastering is admitted to be an adulteration or sophistication.

I obtained samples of sherry from a reliable source, which I have no doubt the shipper honestly believed to have been subjected to no such deliberate plastering; still,from these came down an extravagantly excessive precipitate on the addition of chloride of barium solution.

I afterwards learned that ‘Spanish earth’ was used in the fining.

Why Spanish earth in preference to isinglass or white of egg, which are quite unobjectionable and very efficient?

To this question I could get no satisfactory answer directly, but learned vaguely that the fining produced by the white of egg, though complete at the time, was not permanent, while that effected by Spanish earth, containing much sulphate of lime, is permanent.

The brilliancy thus obtained is not lost by age or variations of temperature, and the dry sherries thus cooked are preferred by English wine-drinkers.

The sulphate of potash which, by the action of sulphate of lime, is made to replace bitartrate, is so readily soluble that neither changes of temperature nor increase of alcohol, due to further fermentation, will throw it down; and thus the wine-maker and wine-merchant, without any guilty intent, and ignorant of what he is really doing, sophisticates the wine, alters its essential composition, and adds an impurity in doing what he supposes to be a mere clarification or removal of impurities.

I have heard of genuine sherries being returned as bad to the shipper because they were genuine, and had been fined without sophistication.

My own experience of genuine wines in wine-growing countries teaches me that such wines are rarely brilliant; and the variations of solubility of the natural salt of the grape, which I have already explained, shows why this is the case.

If the drinkers of sherry and other white and golden wines would cease to demand the conventional brilliancy, they would soon be supplied with the genuine article, which really costs the wine-merchant less than the cooked product they now insist upon having.

This foolish demand of his customers merely gives him a large amount of unnecessary trouble and annoyance.

So far, the wine-merchant; but how about the consumer?

Simply that the substitution of a mineral acid—the sulphuric for a vegetable acid (the tartaric)—supplies him with a precipitant of lithic acid in his own body; that is, provides him with the source of gout, rheumatism, gravel, stone, &c. , with which _English_ wine-drinkers are proverbially tortured.

I am the more urgent in propounding this view of the subject, because I see plainly that not only the patients, but too commonly their medical advisers, do not understand it.

When I was in the midst of these experiments I called upon a clerical neighbour, and found him in his study with his foot on a pillow, and groaning with gout.

A decanter of pale, choice, very dry sherry was on the table.

He poured out a glass for me and another for himself.

I tasted it, and then perpetrated the unheard-of rudeness of denouncing the wine for which my host had paid so high a price.

He knew a little chemistry, and I accordingly went home forthwith, brought back some chloride of barium, added it to his choice sherry, and showed him a precipitate which made him shudder.

He drank no more dry sherry, and has had no serious relapse of gout.