General Considerations.—Wines, from the time of their first fermentation down to the time of their degeneration and decay, are constantly undergoing change. Until they have acquired a certain age, varying in each case with the quality and nature of the liquid, they do not possess those qualities which make them an agreeable, healthful beverage. The care to be bestowed upon them in their general treatment not only includes what is necessary for their preservation, but also what is necessary to age them by developing in them all the good qualities of which they are susceptible, and the means of preventing and remedying their defects and diseases.
A New Wine, when first fermented, is quite different from one even a few months old, in respect to color, flavor, and aroma. But the quality which it may acquire depends upon the proportion of different substances which it contains. Some wines, poor in alcohol and deficient in tannin, will develop their best qualities and begin to degenerate very soon after fermentation. Such should be consumed as soon as their insensible fermentation is completed; it is useless to attempt to age them; while those which are stout, firm and full-bodied must be kept several years to be completely developed.
The Bouquet and Distinctive Flavor of a wine, according to Mr. Boireau, generally, are not perfectly developed until defecation is complete—that is to say, until, after several months’ repose under proper conditions, they have ceased to deposit insoluble matters, and no longer mineral and vegetable salts, ferments, and coloring matter are precipitated.
Old Wine, then, differs from a new wine of the same origin by its color, its aroma, and flavor, and the difference is due to several causes.
The Color of old red wine is less dark on account of the precipitation of a part of the coloring matter, which, rendered insoluble by the formation of different combinations, has been carried down with the lees. The red color becomes tawny in time.
The Aroma of old wine is more agreeable, being largely due to ethers which are formed by a combination of the alcohol with the acids, and because the other aromatic principles are no longer masked by the carbonic acid which is disengaged when the wine has been recently fermented.
The Difference in Flavor is due to several causes, such as the loss of a great part of the mineral and vegetable salts, which have become insoluble by combination with the tartaric, acetic, and malic acid, and their consequent precipitation, and also to the deposit of a portion of the coloring matter.
So that when a wine is old, having been well cared for, it contains less coloring matter, vegetable and mineral salts, acids free and combined, tannin, ferments, mucilage, alcohol, etc., than when first fermented.
Influences which Develop, also Destroy.—Pellicot, quoting Béchamp, says that a wine ages and improves under influences analogous to those which spoil it, and he, himself, carries the idea a little farther, and adds, that the influence which produces the amelioration in a wine—which ages it—will, after having brought about the improvement, cause it to deteriorate, unless its action is opportunely suspended.
It must also be understood that certain influences which will greatly improve a strong, alcoholic, or a sweet wine, might in a short time entirely ruin a weaker one, or a dry wine.
Influence of the Air.—When a wine of ordinary strength, a table wine, comes into immediate contact with the air, a portion of its alcohol evaporates, it loses its bouquet and flavor, and if long exposed, a whitish scum is formed on its surface, called flowers. These have already been described in the chapter on fermentation as micoderma vini and micoderma aceti. A disagreeable flavor is communicated to the wine which the French call goût d’ évent, and the wine is said to be éventé, or flat; and it becomes turbid, and loses its transparency. Sometimes when the wine still contains sugar the flowers are not formed, but a second alcoholic fermentation sets in, and it works. If the wine is not immediately freed from contact with the air, it acidifies, becomes pricked, and by degrees turns to vinegar. (See Acetic Fermentation.) And if still longer exposed, putrid fermentation sets in.
Sweet wines, whose alcoholic strength exceeds 16 per cent., and which contain a good deal of sugar, are not so liable to be injured by the influence of the air. Not only does their high degree of spirit interfere with acetic and putrid fermentation, but an insensible alcoholic fermentation sometimes takes place, and the supply of alcohol is kept up. But in time, as the sugar disappears, the alcohol becomes enfeebled by evaporation, and then acetic fermentation sets in, as in the weaker wines.
In the sherry countries it is considered necessary that the wine should be exposed to the action of the air, and therefore the casks are not kept full, and flowers are considered a good sign. In a few instances, where the wines are strong enough to bear it, aging may be hastened by some exposure to the air, but great care must be taken that they are not left too long under its influence, or disorganization may ensue. It must, however, be laid down as an almost universal rule, that the casks must be kept full and well bunged. (See Ulling.)
Variations of Temperature affect wines like other liquids by contraction and expansion. When a full cask is put in a cold place, the wine contracts and leaves a vacant space; then it must be filled up or the wine drawn into a smaller cask. If the temperature of the wine in a full cask is raised, the liquid expands, and is apt to cause leaks; the sediment is liable to rise and give the wine a flavor of the lees.
Influence of Heat.—Guyot says that the higher the degree of heat to which wines are exposed, the greater their internal activity. Those subjected to 15, 20, 30 degrees, Celsius, (59°, 68°, 86° F.), sooner arrive at maturity, if young, at old age, if ripe, and at decrepitude, if old, than they would at a temperature of 10° C. (50° F.) From which the conclusion is drawn, that wines which have nearly or quite reached their maturity must be protected from heat, or at least from that of an elevated temperature, and that old wines should be kept in as cool a place as possible.
Aging by Heat.—On the other hand, if we wish to hasten the maturity of our wines, we can do so by keeping them in a warm place rather than in a cool cellar. The younger the wines, and the more sugar and alcohol they contain, the more they will gain, and the less risk will they run if subjected to a temperature of from 60° to 86° F. For example, sweet wines which are only ripe at thirty or forty years will mature in fifteen or twenty years, at 68° of heat, and in five or ten years, at 86°; a Bordeaux or a Hermitage wine which at 50° would be made in eight or ten years, would certainly be made in four or five years at from 59° to 68°, and in two or three years at 77° or 86° of heat. He says that a temperature between 40° and 90° C. (104° and 194° F.) will disorganize many kinds of wine, particularly red wines and those which have remained long in the fermenting vat, though it will not have that effect upon all wines.
It is well known that the inhabitants of many southern countries are accustomed to expose their wines to a considerable degree of heat to hasten their maturity, and different methods are employed for the purpose, and it is important to know what kind of wine will be improved and what injured by the practice. On this subject Boireau says, that after many experiments, he can affirm that if the heat exceeds 30° C. (86° F.), it is injurious to the grand mellow wines of the Gironde; also to wines of a delicate bouquet whose alcoholic strength does not exceed 12 per cent. Fine wines which possess both an aromatic taste and bouquet, a fruity flavor, and a pronounced mellowness, by heat take on a certain tawny flavor of worn out wine; but they become dry, lose their mellowness, and coolness, and acquire a cooked flavor, which changes their nature and gives them an analogy with the wines of the south of France. This taste covers their natural flavor and renders them common.
He goes on to say that wines subjected to the action of heat in direct contact with the air, loss by evaporation a part of their alcohol; the oxygen deprives them of a part of their color, and if the influence is prolonged, they become weak and greatly deteriorated. Exposed to heat in imperfectly closed vessels, they deposit, and take the tawny flavor (goût de rancio) if their alcoholic strength exceeds 16 per cent.; but if feeble in spirit, and they remain long in this condition, the oxygen transforms a part of their alcohol into vinegar. In receptacles kept full and well stopped, they undergo but few constitutional changes, if the heat does not exceed 158° F.; but, nevertheless, a small part of their coloring matter is precipitated, and their taste is sensibly changed. A flavor of cooked wine is found, and a slight odor of the lees, no matter how quick the heating.
Whatever the kind of wine operated upon, care must be taken not to carry the heat too high, for it will decompose and precipitate certain principles in dissolution in the wine, and change its natural flavor. After cooling, voluminous deposits will be found, and the cooking will give the wine a disagreeable flavor and an odor of the residue of a still. The extreme limits of from 113° to 158° F. should not be exceeded, and the greater the heat the shorter should be the exposure to it.
Generally speaking, the wines which gain the most by heating, either by artificial means or by leaving them in casks well bunged, but in ullage, in warm store rooms, are strongly fortified liqueur wines. And in order that they be not injured under those conditions, they should contain at least 18 per cent. of pure alcohol. And as they will gradually lose a little of their spirit by evaporation, their alcoholic strength should be taken from time to time, and they should be kept up to the indicated degree by fortifying.
Preserving Wine by Heat.—Aside from the question of aging wine by the effect of heat, Pasteur has attempted to show that wines can be kept without change, if the temperature is raised for a short time to 130° or 140° F. This is on the theory that wines become flat, pricked, turned, or rotten, owing to secondary fermentations, and that each change is due to the action of a particular ferment, as stated in the chapter on fermentation; and that this degree of heat destroys the action of these ferments—in fact, kills them. It is owing to the presence of the alcohol, that they are destroyed by this degree of heat, for a must which has been raised to the boiling point still ferments according to the experience of Boireau and of Pellicot. The first named gives the results of his experiments in heating wines according to Pasteur’s plan. The wine was in bottles, and the heat was gradually raised to 52° C. (125.6° F.) In comparing the wines treated with unheated wines kept under the same conditions, he found that the wine which had been heated could support contact with the air with less injury than the unheated, but that nevertheless it became flat, covered with flowers, and acidified even in closed vessels which were not completely full; also that fine wines generally are injured by the process. The wines experimented upon had from 10 to 10½ per cent. of alcohol.
It is a costly process to subject wine to a high artificial heat, and owing to the doubt which yet seems to attend the matter, but few are likely to go to the expense.
Influence of Cold.—Most authors have something to say on the subject of congealed wines, and undoubtedly the liquid may be concentrated by freezing a portion of the water, and drawing off the remaining liquid. Those living in cold countries can try the experiment, but it will certainly not be practiced in California.
Mr. Boireau says that the liquid remaining acquires a flavor similar to that possessed by wines which have been heated; that fine wines of a delicate bouquet and flavor acquire a commoner flavor than those in their normal state.
Treatment of Frozen Wines.—It may not be amiss to indicate what treatment a wine should receive in case it has been frozen and has thawed again. It becomes turbid, loses part of its color, and several matters are precipitated, or remain in suspension, and it is liable to ferment when the temperature rises. The last named author says that it should be put in a place of even temperature, and if necessary, it should be fined; in which case it should be fortified with a strong wine of the same nature, or a small amount of brandy.
Influence of Light.—Guyot says that the direct light of the sun causes wine to work, especially red wine, and that it has an injurious effect upon its composition and color; and the coloring matter being decomposed, or modified, acts upon the other elements and makes the wine turn. And hence the wisdom of putting wine in colored bottles. It is only the direct light of the sun, however, that is to be avoided, for a dim light, light reflected or polarized, and moonlight and artificial light are not sufficiently powerful to produce a sensible effect.
Aging by Sunlight.—Exposure to the rays of the sun has been resorted to for the purpose of aging wine, but Boireau says that it is not favorable to all, and is least suited to those whose alcoholic strength does not exceed 15 per cent. He says that the direct rays of the sun falling upon bottled wines will promptly precipitate the coloring matter, and that the effect is greater where the bottles are not completely filled and corked with the needle. If the bottles are wrapped in paper, or if the wine is in casks, the aging is less rapid. He shows by experiment that insolation is advantageous only to wines of more than 15 per cent. of alcohol, to sweet wines, and wines fortified up to 18°, intended to be treated as the wines of Madeira, i. e., baked. But wines of about 10 per cent. of spirit will not endure this method of aging without more or less deterioration by souring.
Effect of the Motion of Voyages.—Wines age more rapidly if kept in motion, and hence, in part, the good effect of a long voyage. Strong, sweet wines, are undoubtedly greatly improved by the motion consequent on transportation, as well as by the heat, but constant agitation will cause weak ones to go rapidly through the periods of their existence, and degenerate.
Wines Suitable for Shipment.—And Dr. Guyot adds that a wine which does not contain 12 per cent. of alcohol and 6 per cent. of sugar, crosses the equator with great difficulty, even in bottles. In wood it should be young and contain 20 per cent. of spirit, or sufficient sugar to make up that amount. For a voyage in Europe, or to America direct, he says that the wines of Bordeaux, Burgundy, and of Champagne, of 10 to 12 per cent. of spirit and 2 to 4 per cent. of sugar, behave well if young or in bottles.
Mr. Boireau, however, says that wines proper for exportation, and which will keep in tropical climates, where good cellars and good care are generally wanting, are those which possess naturally or by addition a high alcoholic title, a solid, but bright and handsome color, a clean taste, and perfect limpidity. Sweet, fortified wines best fulfil these conditions. He says that liqueur wines, for shipping to the tropics, should have at least 18 per cent. of pure alcohol; below that they ferment, their saccharine matter is transformed into alcohol, their strength diminishes, and they end by becoming pricked. Dry wines, to be sent to those countries, should have the same strength, unless the casks are kept full. He adds, however, that these remarks only apply to those wines which on their arrival do not receive the usual care, such as filling the casks, clarifying and racking, and are not kept in suitable places; and that a good firm wine of the south of France, which has naturally at least 12 per cent. of alcohol, can be shipped without fortifying.
The motion and the high temperature to which wines are subjected in transportation also cause a loss of color by precipitation, particularly if they lack tannin. Wines which are sufficiently strong in alcohol, but from lack of tannin want firmness and body, are liable to acidify. Therefore, wines too poor in tannin should not be shipped abroad. The greater part of the wines of the Gironde having plenty of tannin, can be safely shipped if fortified to 11 per cent., and the grand wines of less alcohol are safe if shipped in bottles.
In Shipping a New Wine, whose sensible fermentation is finished, the motion often causes a new disengagement of carbonic acid, and sometimes in sufficient force to burst out a head of the cask, unless vented. Of course, such wine should not be shipped, except under conditions which admit of careful supervision. If transported short distances, a small gimlet hole should be kept open near the bung, in which three or four straws may be placed with the heads or spikes on, or a small tin tube with a button at the top may be placed in the hole and bent inside the stave, having sufficient play to allow the gas to escape. Must is shipped in the same way.
Other Motion, such as Jarring and Trembling, produced by loud noises and bypassing teams and by factories, act injuriously upon wines, causing them to behave badly and to deteriorate. Guyot also says what may be by some deemed fanciful, that musical sounds hasten the development of wine; and that most old wines will turn in a cellar transformed into a music hall.
Fining is also resorted to for the purpose of aging wine, producing results somewhat similar to the effects of time. But it should be performed with the care and subject to the conditions mentioned in the proper place. (See Fining.)
Aging Generally.—Before subjecting a wine to any of the processes for artificial aging, care should be taken, says Mr. Boireau, to precipitate the matters held in suspension, and to render it perfectly limpid.
Grand wines, however, should never be subjected to the treatment, for if a premature development of bouquet is obtained, it is at the expense of that precious quality, mellowness. For to-day, gourmets and consumers of refined taste do not select wines which have a bouquet, if they are also dry and harsh to the palate; such wines are only too plenty. They esteem above all those wines which in aging have kept their fruity flavor, their velvety smoothness, that unctuosity which can only be preserved in keeping them in a place having a regular temperature (averaging 60°), in well closed receptacles, by bringing about the defecation of their lees and the deposit of their ferments by opportune rackings without contact with the air, and by fining them as little as possible.
If, for want of care or suitable places, the wines work, enter into fermentation, their mellowness diminishes, and when neglected they become dry.
The Wines which Gain the Most by the Aging Processes mentioned, are: 1st, Wines excessively rough and overcharged with color; 2d, fortified wines, whose minimum degree of alcohol is 18 per cent.; 3d, sweet wines fortified to 18 or 20 per cent.
Those which remain too harsh should be fined with a strong dose of gelatine; continued agitation after this will make them smoother.
Fortified wines, dry or sweet, age very quickly, if subjected to agitation and afterwards to insolation, if followed by a complete clarification; but it is important to fortify them anew, for the alcohol evaporates, and below 15 per cent. they would sour instead of acquiring bouquet. It is also sometimes necessary to add sugar to sweet wines so treated.