The mousey taste may be more or less intense, and wines affected produce a dry feeling in the mouth when they are tasted. If a wine has this taste in a very slight degree it is not noticed immediately; it often happens that after passing judgment on a wine, one's opinion has to be modified by a mousey taste which is not perceived at first. If the defect is pronounced, it is perceived immediately by the nose; the odor and taste too, in this case, are so disgusting as to be sickening.
This taste is easily produced by allowing the cap to become overheated during fermentation, or by heating grapes before crushing them. With time this taste tends to disappear, but when somewhat pronounced it diminishes, leaving the wine with a somewhat acrid taste.
The fine experiments of Dubceuf and J. Bruhl on the action of sulphurous anhydride, or acid, on micro-organisms, have an important bearing here.
They have deduced from their experiments the folio wing conclusions:
Sulphurous acid, when used in excessive quantities, takes away from the quality and color of the wine, and gives it a bitterish, astringent, and displeasing taste. In time the sulphurous acid changes to sulphuric, and then into sulphate of potassium. This is why in many wines is found a certain quantity of this sulphate, which is dangerous to health, and, when sufficient of it is present, would lead to the belief that the wine had been plastered.
In practice it is good to remember that the more alcoholic a wine the more sulphurous acid it will dissolve or absorb.
Nessler, making a comparison of water and wine at 9 per cent of alcohol, filled a barrel quickly with each, after having burned as much sulphur as the air in the barrel would consume, and found that the water absorbed .01035 per cent of sulphurous acid, and the wine .01346 per cent.
The quantity of sulphurous acid which a wine will absorb in process of keeping cannot be exactly stated, as it depends on the number of sulphurings, the amount of sulphur burned, or, when the sulphur is burned directly in the cask, on the amount of oxygen there.
According to Weigert the quantity of oxygen in a cask of one hectolitre is 21 litres or 30 grammes. By burning an equal quantity of sulphur 60 grammes of sulphurous acid are formed. When the cask is filled all this is not dissolved, because part is oxidized immediately, and part escapes into the air as the wine enters the cask; thus, the total amount absorbed by the wine is reduced to about 10 or 11 grammes.
Many high-class and fine wines, in aging, develop characteristic bouquets; but besides bouquet these wines have seve, which artificially perfumed wines lack altogether or have little of in proportion to their fragrance.
Besides the odors which we call good, which have been added artificially, we have also bad odors which are absorbed from the air by the grapes or the wine, such as the odor of tobacco, of grass, etc.
To remove this taste recourse is had to olive oil, lemons, or refermentation with a small quantity of fresh grapes.
Clarifications and rackings with contact of the air will often destroy or notably diminish the stem taste. When it is desired to prolong the contact of the wine with the pomace, stemming is to be recommended.
This defect may be occasioned by the smoke given off by ill-constructed stoves used to heat the ferm en ting-room or cellar; or it may be due to unfavorable climatic conditions during the vintage. It has been stated that musts corrected by the addition of cane sugar will sometimes give wines with this taste.
With the smoky taste a wine loses its brightness, becomes cloudy, and if not cured by sulphuring, changes into a liquid not to be tolerated by even the most uncritical palate.
The same causes which tend to produce hydrogen-sulphide in the wine, not excepting plastering when it is done heavily, tend also to form mercaptan. So far no means have been discovered of removing this taste from wine.
Polacci was the first to observe the formation of these products, which have a fetid and persistent odor, and are due to the action of sulph-hydric acid and sulphur on the components of the must and wine; he believes them to be simply ethylic mercaptan. Konig thinks that this reaction is not very probable, as it has never been known to take place in a dilute acid solution.
He believes, on the contrary, that the aldehyde contained in most wines combines easily and directly in a dilute acid solution with sulph-hydric acid to form thio-aldehyde and trithio-alde- hyde. Now these compounds are endowed with a strong, persistent, and disagreeable odor, resembling closely that acquired by wines containing sulph-hydric acid; it may be, therefore, that the mercaptan ic substance spoken of by Polacci is nothing but thio-aldehyde or trithio- aldehyde.
This taste may also originate in imperfectly ripened grapes, which, through the prolonged action of dampness, have commenced to decay. If the grapes are ripe before they commence to decay, the wine will still have something of this taste, but it will be less disgusting and will tend to disappear with time; the wine will, however, always be insipid, and lack frankness of taste.
The French distinguish these two maladies, calling the first " la maladie de la pousse — vin pousse;" in Italian, "malattia del subbollimento;" and the second, "maladie de la tourne — vins tournes;" in Italian, "cercone."
"Maladie de la pousse." — This disease is recognized by the wine spurting out when the vessel in which it has been confined is opened; the wine exercises a strong pressure on the staves of the cask on account of the carbonic acid which is formed; it is from this that comes the term " pousse."
In the glass the wine shows a persistent ring of small gaseous bubbles of a whitish color. If the wine is left exposed to the air it becomes turbid; its color becomes dull with a tendency to yellowish.
The wine has lost its primary flavor, and as the disease progresses, becomes more and more insipid; if it is shaken there is an appearance of silky waves at the surface, caused by the lees which has risen up.
Balard was the first to show the presence in " vins pousses " of a ferment which, according to him, resembles the lactic ferment. He has further shown that in these wines the quantity of volatile acids is increased, the one found in largest quantity being acetic acid.
Bechamp and Stenard have shown that propionic acid is formed in these wines from the tartar and the glycerine. Nickles, on the contrary, is of the opinion that metacetic acid is produced.
Duclaux, who has given much attention to this malady, seems to have proved: (1) That the amount of free acids augments with the progress of the malady; (2) that this increase is made at the expense of the fixed acids of the wine, particularly of the tartaric acid; (3) that the acids formed are propionic and acetic. After having shown this he concludes by saying that all fermentation of the tartar that takes place with the evolution of pure carbonic acid and production of propionic and acetic acids should be called " maladie de la pousse."
Cercone, vin girato, mercuriella, It.; Tourne, vin tourne, vin qui a donne le tour, Fr.). — At this word in an Italian dictionary is written: Cercone — a distiller's term — is said of a spoiled wine, because in becoming thus it works and turns; vappa, lora of the Latins. The lora of the Latins is certainly not the cercone, but family wine, piquette; neither is vappa, since that, according to the dictionaries, should indicate a flat, vapid wine. Vappa vinum insipidum et nullino virtutis, postquam omnino odor saporque optimus evaporavit.
Vin tourne has this peculiarity, that when first poured out it appears sound, but after a short time it tends to become turbid and iridescent.
Under the influence of the oxygen of the air the coloring matter becomes purplish, and precipitates, and the wine acquires a yellowish tint, a sour taste, and a forbidding bitterness.
Wines of this kind when distilled give a brandy having a bitter taste, caused probably by ammoniacal compounds. The alcohol made from them has not always, but often, a strong and pungent odor, and cannot, without being well rectified, be put to the ordinary uses of wine alcohol, that is, the manufacture of vermouth, etc. This odor is sometimes so pungent as to bring tears to the eyes, and, by fractional distillations, it is possible to isolate a certain quantity of croton-aldehyde. (4)This compound is formed, very probably, during the distillation by the condensation of the aldehyde with diminution of water
Balard has found lactic acid in " vins tournes; " Glenard, on the other hand, has found potassic acetate. In the secondary fermentation of " vins tournes," there is a formation of acetic acid, and more especially of lactic and tartronic acids.
"Fat" wines are indigestible, and hard to keep during the hot season, as they are extremely liable to secondary fermentations. The wines in which this defect is usually found, are those grown on moist plains, which are naturally fertile, or made so by the addition of nitrogenous manures, as, for instance, young vineyards where the effect of manuring at the planting of the vines has not worn off. This defect may be avoided entirely, or to a great extent, by a thorough and prolonged aeration of the must, or by the addition of alcohol or tannin(5) to the wine.
Sometimes this defect, when not too pronounced, will partly or wholly disappear after the wine has gone through its slow spring fermentation.
This malady is caused by a micro-organism. A greasy wine, as the malady progresses, loses its fragrance and becomes bitterish; its color becomes dull and tends to turn brown; finally, it loses its natural transparency and brightness. At first it is flat, vapid, and distasteful; and finally, rancid and sour by the formation of lactic acid.
This malady occurs oftener in white than in red wines; in late years, however, it has been found often in red wines on account of the unfavorable conditions for the grapes attaining a complete maturity, such, for instance, as the damages done by insects, cryptogams, and bad weather.
Very probably this deterioration is much more complex than is usually supposed.
Peligot was the first to establish the presence of a micro-organism, of a bacterium. Pasteur, later, demonstrated that this bacterium has the property of transforming the sugar that remains in the wine into a mucilaginous or viscid substance.(6)
Bechamp calls the active ferment of this process Micrococcus viscosus, and the gum which is formed viscosio.
Tannin and alcohol, in certain proportions, prevent the development and action of this bacterium; the conclusion, therefore, is that wines poor in alcohol and tannin, and containing sugar, are subject, especially if white, to become "filant." This explains also the use of tannin, as proposed by M. Francois, of Chalons, to arrest or prevent this malady.
Francois attributes this malady to a peculiar nitrogenous substance, gliandin, a kind of glutin, which seems to have the property of being precipitated by tannin. Nessler affirms, however, that we do not know yet how the tannin acts.
I have already remarked on the complex nature of the malady under discussion. Usually it is held to be owing to a lack or deficiency of tannin. This, however, is not invariably true, since Francisco Selmi has found it in wine made from Lambrusca grapes, and therefore rich in tannin. It seems that in this malady the tartaric acid also suffers changes. Probably on account of these changes Bizzari proposes the use of tartaric acid, 200 to 250 grammes per 100 gallons, as a cure or preventive of the malady.
The best means of preventing or arresting the disease consists of the use of tannin, pasteurizing to destroy the bacteria, racking into sulphured casks, and finally the addition of alcohol to the wine.
Pasteurization is inapplicable in the case of white wines which are destined for the fabrication of champagne, because it not only destroys the bacteria, but also the alcoholic ferments, whose action is necessary to produce the carbonic acid, which renders the wine sparkling.
At the beginning of the development of the disease, forcible agitation of the wine will restore its clearness and fluidity by the disassociation of the bacteria and the dispersion of the mucilaginous matter which envelops the parasite.
Agitation, however, must not be looked upon as a curative measure; the results obtained are only temporary, for the cause of the disease, viz.: the bacterium, is neither destroyed nor removed.
Although cases do occur in which generous wines are attacked by the Mycoderma vini, still it has a decided preference for young and feeble wines. In old and well-defecated wines it develops with difficulty, perhaps because in these wines the elements necessary for its nourishment ( nitrogenous bodies and phosphates) are not found.
The practice of some wine makers with regard to ;'wine flowers" is not in accord with that of those who follow a rational system of wine making. They consider only the development of the " flowers," which they look upon almost as a preservative of the wine, whilst the others sustain the necessity of energetically combatting and preventing the increase of the " flowers," because it is not only dangerous in itself, but is almost always accompanied by the Mycoderma aceti, or Diplococcus aceti, which, the moment circumstances become favorable, commence to replace the Mycoderma vini and cause the acetification of the wine.
When it is thoroughly understood how the " flowers " act it is easy to explain the facts put forward by those who do not consider it dangerous, and also the reasons of those who believe that it should be prevented by all means, and destroyed on its first appearance.
The presence of the " flowers " causes such an absorption of oxygen and development of heat and carbonic acid, as to prevent the growth of any other organism.
Ducleaux has calculated that 80 grammes of alcohol contained in a litre of wine of 10 per cent, needs for its transformation into water and carbonic acid more than 160 grammes, or 100 litres of oxygen.
The conclusions to be drawn from this are evident; they are, that when the cast is well closed, so as to prevent the free entry of air, the dimunition of alcohol, caused by the "flowers" is reduced to a mere trifle, and that the presence of the " flowers "- excluded the action of other micro-organisms.
We must not, however, reason from this that the Mycoderma vini i^ really of use, for if exposure to the air should happen, if, instead of remaining white, the " flowers," as Pasteur noticed, should turn red. then, sooner or later, it will cede its place to other organisms, to tlu vinegar diplococcus, which, as I have shown before, is ready immediately to commence action, finding itself in favorable condition for its development, for the "flowers" itself serves for nutriment; and if there should be a considerable rise in temperature, the conditions are the best possible.
The "flowers" may be destroyed by the addition of sulphurous anhydride or a few drops of alcohol.
With wine in bottles, the development of the " flowers " is prevented by keeping the bottles lying down; if instead the wine is kept in flasks (" fiaschi"), as in Tuscany, or in demijohns, a few drops of the purest olive oil on the surface of the wine will have the same effect.
This defect is recognized by the odor and taste of acetic acid; in tasting, il'.i strongest effect is perceived at the base of the tongue.
If a wine thus affected is not taken in hand immediately (and in truth success is not always sure) and treated with heavy sulphurings or pasteurizing, it soon becomes sour and acetic.
Acetification is due to the action of a micro-organism, the bacterium known under the name of Diplococcus aceti, still commonly called Mycoderma aceti, which increases with a rapidity truly prodigious. Ducleaux tells us that if on a surface of wine a metre square an almost imperceptible amount of these bacteria is allowed to fall, in twenty-four hours the whole surface of the liquid will be covered with a layer of them so closely placed as to be crowded into contact. Thus, there will be three hundred thousand million individuals formed in twenty-four hours.
The rapidity with which the acetic bacterium multiplies explains why a pricked wine, when the temperature is favorable, becomes so quickly completely acetified.
It should be remembered that whilst it is easy to prevent this disease by taking proper precautions in the fermenting-room and cellar, it is difficult, if not impossible, to destroy it when started.
Once a wine has become pricked, instead of trying to effect a cure, it is better to follow the advice of Guyot, who says: "When wine acquires the odor and taste of acetic acid, it is sent to the vingear factory, but is is never attempted to use it as wine.
All the means that have been suggested tor the treatment of a pricked wine may be considered as palliatives only, and not as radical cures. In this regard Carpene writes very justly:
"The neutralization of the acetic acid, which has developed in the wine by the oxidation of the alcohol with potash, soda, lime, magnesia, and their simple or double neutral carbonates and tartrates, seems to be a rational method, but, in reality, is not so. These substances neutralize wholly, or in part, the free, and even the combined acids, and the diminution of the complex acidity of the wine renders the acetic taste less noticeable, but does not completely remove"it. To remove entirely the acetic acid it is necessary to completely neutralize the wine, because the acetic acid combines with the alkaline and earthy-alkaline bases after they have neutralized the tartaric, malic, and succinic acids. Moreover, acetic acid, even when completely combined with a base, gives out, though less strongly, its characteristic odor, so that even after complete neutralization the wine will still have an odor of acetic acid, accompanied besides by a bitter taste, which lingers in the throat, and may be worse than the first fault."
if there is any doubt as to which acid the wine contains, the doubt can be solved by pouring a drop or two of the wine into the palm of one hand, and then rubbing it with the other; if any acetic acid is present its odor will be immediately perceptible on the hands. A milk-sour wine loses some of its fluidity, and its color becomes dull. Sweet, badly defecated wines, especially those rich in albuminoids, are liable to milk-sourness.
The disease appears during the winter or in the spring, and generally in wines poor in acids; it is accompanied by a turbidity of the wL and a change of color. As long as the wine remains in full, well-bu. ged casks, this turbidity and change of color do not occur, but only \v en it is exposed to the air.
Some observers have considered lactic acid as one of the norms I products of alcoholic fermentation, like glycerine, succinic acid, etc.; the truth, however, is, as Pasteur has proved, that whenever the smallest quantity or trace of lactic acid is found in wine it is caused by lactic fermentation.
Whenever the alcoholic fermentation of certain musts, rich in nitrogenous matters, is not well conducted, especially as regards temperature, a certain quantity of lactic acid is very easily formed, which is a bad defect. This happens generally in certain years in warm countries, where the so-called sweet-sour wines are produced.
It is difficult, not to say impossible, to take away the defect of milk- sourness; the different methods proposed, including that of refermenta- tion, do not succeed; consequently, the best thing is to prevent it by a thorough defecation of the must, and a properly regulated fermentation, not allowing the temperature to rise to a point at which the alcoholic ferment becomes inactive, and thus preventing it from reducing all, or the major part, of the glucose contained in the must.
To these causes, most probably, should be added another, that of the reduction of s\il- phates by micro-organisms, a reduction first noticed bv Planchud, who attributed it to vital action. This action has been found by Etard and Olivier to be due to algae of the group of oscillators, called Beggiatoa (B. roseo-persicina, B. mirabilis, B. alba). Other algce of the genus Ulothrix have the same property.
Is it not possible that micro-organisms might be found in wine resembling and acting the same way as those algae found in sulphurous waters?
(2)It may perhaps be useful to note that the lees may become the seat of a bacteroid fermentation Independently of any anterior disease in the wine. Thus, according to the experiments of Ravizza; the wine and lees may become the prey of bacteria without the aid of molds or other micro-organisms that destroy the acids. The temperature most favorable to the development of bacteria in the lees seems to be from 77° F. to 86° F. Below 77° F. the phenomena accompanying the life of these bacteria decrease, and towards 50° F. cease altogether. The practice, then, in racking, of separating the last layers of wine, that is, the part lying in contact with the lees, from the rest is a good one, and this wine may be considered of inferior quality, either because it lacks a clean, fresh taste, or because it is sometimes cloudy.
(3) Fruity is very often used in English with the inappropriate meaning of somewhat sweet - Trans.
(4)Recently, Professor Comboni, in distilling a wine made by blending Marzemino and Black Pniot, which had been attacked by the bitter fermentation, found in the distillate a considerable amount of aldehyde and formic acid. These products are certainly formed during the progress of the secondary fermentation, for they are not found at all in the same wine when sound.
(5)The addition of a little tanninized wine is better than the direct addition of tannin. Tanninized wine may be prepared thus: Take a small cask, holding, for example, about25 gallons; fill it with a strong wine, or one made so by the addition of 1 or 1% gallons of alcohol of 94° C.; into the wine put about 35 pounds of grape seeds which have not been fermented. For the first few days the wine should be stirred from time to time, and then left to itself. After about ten days the liquid part is drawn off, and is then a wine heavily charged with tannin, which serves excellently for the purpose above noted; for that purpose a dose of 1 or 2 gallons of the tanninized wine to 100 of the wine to be treated is about the right proportion.
If a tanninized wine is needed for the defecation of the must, it is prepared thus: Take 5 gallons of alcohol and 10 gallons of wine, put in a small cask, and add about 18 or 20 pounds of seeds, and treat as in the former case; 1 or 2 gallons of this is sufficient to thoroughly defecate 100 gallons of must.
(6)The bacterium of "La Graisse" put into a solution of sugar containing albuminoid and mineral substances acts upon the sugar and transforms it into a kind of gum, mannite, water, and carbonic acid. Thus, 100 parts of cane sugar will give 50.09 parts of man- nite, 43.5 of gum, besides water and carbonic acid.
Monoyer proposed to account for this transformation by two chemical equations, the first of which would give mannite and carbonic acid, the second gum and water, as formed from the glucose.
Schmidt-Mulheim is about of the same opinion, he believing that the viscous fermentation consisted of two processes, the first of which gave mannite and carbonic acid, and the second the viscid substance.
Kramer has studied this ferment. He examined three wines afflicted by it, and besides Saccharomyces ellipsoideus, Saccharomyces micoderma, etc., he found an extremely minute bacillus 2 to 6 n long, and .6 to .8 ft thick. He failed to cultivate this bacillus on potato, agar agar, etc., but by putting a little of the infected wine into a new (three months) white sterilized wine and with 3 per cent of glucose, he found that the bacillus developed well and rendered the wine " filant," but only when the air was completely excluded by covering the wine with a layer of oil. With access of air there was very little development of the bacillus, and instead ail increase of the other ferments of the wine. Kramer has called this ferment Bacillus viscus vini.
The peculiar kind of gum produced by the viscous fermentation of the sugar renders the wine viscid and glutinous. In its properties it resembles dextrine more than it does gum arabic.
The viscid substance, according to Kramer, appears to be a product of assimilation of the organism, whilst the carbonic acid and mannite, which are formed contemporaneously, are products of the fermentation; a constant proportion between the first and the last substances does not exist.
The gum can be isolated and purified by precipitation with alcohopl, dissolving the precipitation with water, and re-precipitating with alcohol. Dried at 100 C, it forms a brown, amorphous body, which in water, without being dissolved, swells up greatly and forms a kind of glue. It has no acid reaction.