Wine has been made for several thousand years by fermentation of the juice of the grapes. Like other fermentations, many primitive procedures have been supplanted by improved science and engineering to reduce costs and to make more uniform products. But now, as always, the quality of the product is largely related to grape, soil and sun, resulting in a variation in flavor, bouquet, and aroma. The color depends largely upon the nature of the grapes and whether the skins are pressed out before fermentation. Wines are classified as natural (alcohol 7 to 14%), fortified (alcohol 14 to 30%), sweet or dry, still or sparkling. Fortified wines have alcohol or brandy added. In the sweet wines some of the sugar remains unfermented.
For the manufacture of dry red wine, red or black grapes are necessary. The grapes are run through a crusher, which macerates them but do not crush the seeds, and also removes part of the stems. The resulting pulp, or must, is pumped into 11,000 to 38,000 L tanks, where sulfurous acid is added to check the growth of wild yeast. An active culture of selected and cultivated yeast equal to 3 to 5 percent of volume of juice is added. During fermentation, the temperature rises, so that cooling coils are necessary to maintain a temperature below 30oC. The carbon dioxide evolve carries the stems and seed to the top, which is partly prevented by a grating floated in the vat. This allows extraction of the color and the tannin from the skins and seeds. When the fermentation slow up, the juice is pumped out of the bottom of the vat and back over the top. The wine is finally run into closed tanks in the storage cellar, where, during a period of 2 or 3 weeks, the yeast ferments the remainder of the sugar. The wine is given a cellar treatment to clear it, improve the taste, and decrease the time of aging. During this treatment the wine is first allowed to remain quite for 6 week to remove part of the matter in suspension, and then racked for clarification. Bentonite or other diatomaceous earth, may be used for clearing, 20 to 185 g being stirred into every 100 L of wine. An insoluble precipitate with the tannin is also formed. Extra tannin may also be added, and the wine racked and filtered through diatomaceous earth, asbestos, or paper pulp.
The wine is corrected to commercial standards by blending it with other wine and by the addition of sugar, acids, or tannins. It is standard procedure to chill some wine for the removal of argols or crude potassium acid tartate, which constitute the commercial source of tartaric acid and its compounds. This treatment also gives a more stable finished wine. By quick aging methods it is possible to produce a good sweet wine in 4 months. These methods include pasteurization, refrigeration, sunlight, ultraviolet light, ozone, agitation, and aeration.
The wine may be held at about freezing for 3 weeks, to a month, and a small amount of oxygen gas bubbled in. Then the wine is racked, clarified, and further filtered in the usual manner. The wine trade is large and growing rapidly in the United States.
For the manufacture of dry red wine, red or black grapes are necessary. The grapes are run through a crusher, which macerates them but do not crush the seeds, and also removes part of the stems. The resulting pulp, or must, is pumped into 11,000 to 38,000 L tanks, where sulfurous acid is added to check the growth of wild yeast. An active culture of selected and cultivated yeast equal to 3 to 5 percent of volume of juice is added. During fermentation, the temperature rises, so that cooling coils are necessary to maintain a temperature below 30oC. The carbon dioxide evolve carries the stems and seed to the top, which is partly prevented by a grating floated in the vat. This allows extraction of the color and the tannin from the skins and seeds. When the fermentation slow up, the juice is pumped out of the bottom of the vat and back over the top. The wine is finally run into closed tanks in the storage cellar, where, during a period of 2 or 3 weeks, the yeast ferments the remainder of the sugar. The wine is given a cellar treatment to clear it, improve the taste, and decrease the time of aging. During this treatment the wine is first allowed to remain quite for 6 week to remove part of the matter in suspension, and then racked for clarification. Bentonite or other diatomaceous earth, may be used for clearing, 20 to 185 g being stirred into every 100 L of wine. An insoluble precipitate with the tannin is also formed. Extra tannin may also be added, and the wine racked and filtered through diatomaceous earth, asbestos, or paper pulp.
The wine is corrected to commercial standards by blending it with other wine and by the addition of sugar, acids, or tannins. It is standard procedure to chill some wine for the removal of argols or crude potassium acid tartate, which constitute the commercial source of tartaric acid and its compounds. This treatment also gives a more stable finished wine. By quick aging methods it is possible to produce a good sweet wine in 4 months. These methods include pasteurization, refrigeration, sunlight, ultraviolet light, ozone, agitation, and aeration.
The wine may be held at about freezing for 3 weeks, to a month, and a small amount of oxygen gas bubbled in. Then the wine is racked, clarified, and further filtered in the usual manner. The wine trade is large and growing rapidly in the United States.
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