This section is from the book "The Manufacture Of Liquors, Wines, And Cordials, Without The Aid Of Distillation", by Pierre Lacour. Also available from Amazon: Manufacture of Liquors, Wines, and Cordials, Without the Aid of Distillation.
Wine is the fermented juice of the grape. The juice of sweet grapes consists of a considerable quantity of grape sugar, a peculiar matter of the nature of ferment or yeast, and a small portion of extractive tannic acid, bitartrate of potassa, tartrate of lime, common salt, and sulphate of potassa, the whole dissolved or suspended in a large quantity of water. This grape juice contains all the essentials to the production of vinous fermentation, and requires only the influence of the atmosphere and a proper temperature to convert it into wine.
Preparation of Wine. - When the grapes are ripe they are gathered and trodden under foot, in wooden vessels with perforated bottoms, through which the juice, called the must, runs into a vat placed beneath. The temperature of the air being about 60°, the fermentation gradually takes place in the must, and becomes fully established after a longer or shorter period. In the meantime the must becomes sensibly warmer and emits a large quantity of carbonic acid, which causes the more solid parts to be thrown to the surface in a mass of froth, called the head; the liquor from being sweet becomes vinore, and assumes a deep red color, if the product of red grapes. After a while the fermentation slackens, when it becomes necessary to accelerate it by thoroughly mixing the contents of the vat. When the liquor has acquired a strong vinous taste, and becomes perfectly clear, the wine is considered formed, and is racked off into casks; but even at this stage of the process the fermentation continues for several months. During this period a frothy matter is formed, which, for the first few days, collects round the bung, but afterwards precipitates along with coloring matter and tartar, forming a deposit which constitutes the wine lees.
Division and Nomenclature. - Wines, according to their color, are divided into white and red, and according to their taste and other qualities are either spirituous, sweet, dry, light, sparkling, rough, or acidulous.
Red wines are derived from the must of black grapes, white wines from white grapes, or from the juice of black grapes fermented apart from their husks. The other qualities of wine above enumerated depend on the relative proportions of the constituents of the must, and on the mode in which the fermentation is conducted. The essential ingredients of the must as a fermentable liquid are water and sugar, and a ferment. If the juice be very saccharine and contain sufficient ferment to sustain the fermentation, the conversion of the sugar into alcohol will proceed until checked by the production of a certain amount of the latter, and there will be formed a spirituous or generous wine; if, while the juice is highly saccharine, the ferment be deficient in quantity, the production of alcohol will be less, and the redundancy of sugar proportionally greater, and a sweet wine will be formed. When the sugar and ferment are in considerable quantities, and in proper relative proportions for mutual decomposition, the wine will be strong-bodied and sound without any sweetness or acidity, and of the kind called dry; a small proportion of sugar can give rise to only a small proportion of alcohol; and, consequently, the less saccharine grapes will generate a comparatively weak or light wine, which will be sound and stable in its constitution, in case the ferment is not in excess, but otherwise liable to pass into the acetous fermentation and become acescent. In case the wine is bottled before the fermentation is fully completed, the process will proceed slowly in the bottles, and carbonic acid generated, not having vent, will impregnate the wine, and render it effervescing and sparkling.
The rough, or astringent wines, owe their flavor to a portion of tannic acid derived from the husk of the grape, and the acidulous wines to the presence of carbonic acid, or an unusual proportion of tartar. Several of the above qualities often co-exist; thus a wine may be spirituous and sweet, spirituous and ough, rough and sweet, light and sparkling, etc.
Wines are known in commerce by various names, according to their sources; thus Portugal produces Port and Lisbon; Spain, Sherry, St. Lucar, Malaga, and Tent; France, Champagne, Burgundy, Hermitage, Vin de Grave, Sauterne, and Claret; Germany, Hock and Moselle; Hungary, Tokay; Sicily, Sicily Madei and Lissa; the Cape of Good Hope, Constantly: Madeira and the Canaries, Madeira and Tene-riffe.
Wines prepared from vinous fermentation, or wines prepared from saccharine fermentation, consist of a small portion of saccharine matter, suspended in a large quantity of water, and by the necessary requisites it is fermented, and when in this state it is a pleasantly acidulated liquid, caused by the presence of carbonic acid and alcohol, which is the result of fermentation. The farther progress of fermentation is checked by the addition of alcohol, and the flavoring ingredients are added, which are supposed to add to the fermented liquor a taste and aroma peculiar to wine fermented from the grape. The ingredients consist of aromatics, cane and grape sugar coloring, tannin, alkali, acid, starch, mucilage, perfumes, ethers, etc, with the view to different ends; thus sugar or honey for sour wines, grape sugar for pleasantly sweet wines, aromatics and alcohol for light-bodied wines, tannin for rough wines, and starch mucilage for poor and light wines, etc., etc. The length of time necessary for fermentation, the proportions of water, saccharine, and fermentative matter, and the quantity, quality, and effects of the aromatics, etc, added, are necessary in detail to the end of furnishing a comprehensive view of the manufacturing process generally.
The time of a vinous fermentation commencing is uncertain; much depends on the quality and composition of the liquid to be fermented; on its local situation, and the season or weather - the temperature should be uniform, and of about sixty to seventy degrees, and often the temperature has to be increased.
When fermentation is slow,it is facilitated by agitating or stirring the mass. The commencing of fermentation may be known by the fluid being in a higher temperature than that of the existing atmosphere, and can be distinguished by its taste, smell, and appearance. The length of time necessary for fermentation is from four to ten days. The best plan to ascertain when a fluid has fermented sufficiently, is by that infallible guide, the palate; if the fluid contains carbonic acid, it will be known by the liquid possessing that peculiar, pungent, pleasantly though slightly biting taste to the palate; the fermentation is discontinued by the addition of from five to fifteen per cent, of alcohol, though wines to keep well and prevent acidity should contain from eighteen to twenty-two per cent, of alcohol. Wines that become sour, turbid, or otherwise injured when exposed to the air, is owing to a deficiency of alcohol. Wine thus charged has a fine body, and a pleasant, heating taste to the palate. As a general rule the alcohol should be free from grain oil, as the odor is objectionable, and would tend to the destruction of any other odor that might be added. Alcohol unrectified is only suited for some of the light-bodied wines, where the odor is of no importance; in the cheaper wines, the smell of the grain oil can be concealed by the addition of aromatics.
The aromatics used to give the taste of wine are various; the most prominent are ginger, spice, cloves, calamus; horse-radish, ground mustard, etc., give to wines, liquors, and cordials, a peculiar aromatic, stimulating taste, that is found in pure wine.
Fresh bitter almonds, peach kernels, sweet almonds, give to wines and cordials a rich, nutty flavor. Care should be taken in selecting the fresh almonds, etc., as the rancidity would be clearly perceptible in a clean clear article of wine or cordial.