In general grapes are not picked for wine-making until they have reached full maturity thus insuring a higher sugar content, richness of flavor and perfect color. It is customary to determine the composition of the must as to sugar and acid content by various instruments devised for the purpose and if it lack sugar this ingredient is added; if it be too acid water is added; or the composition may be otherwise changed depending upon a number of circumstances though manifestly reputable wine-makers change the natural grape juice as little as possible. Soon after harvesting the grapes are crushed. The ancient method, which still prevails in many parts of Europe, was to tramp the grapes with bare feet or wooden shoes. Tramping is for most part superseded by mechanical crushers which break the skins but do not crush the seeds. For some wines the stems of the grapes are removed; for others it is essential that the grapes be not stemmed. Stemming may be done by hand, by a rake over a screen, or by specially devised machines. If white wine is to be made the juice is separated from skins and pulp at once; if red wine is desired fermentation takes place in the crushed grapes or marc.
Fermentation is carried on in large tanks or vats varying in capacity from 1000 gallons to 10,000 gallons or more. Some wine-makers prefer open vats, others keep them closed. The duration of fermentation depends upon many conditions and varies from two or three to fifteen or twenty days, depending upon the amount of sugar in the must, the temperature, activity of ferments, etc., etc. Wine-makers observe several distinct stages of fermentation which must be closely watched and controlled. A most important influence is exerted on fermentation by temperature. The limits below which and above which fermentation does not take place are 55° and 90°F. In general it is desirable that fermentation take place at temperatures ranging about 70°. When it is found that the sugar is practically all converted into alcohol, or that such conversion has proceeded far enough, the new wine is drawn or pumped from the fermenting vats into casks or barrels where it ages though it may require special treatment for clearing. Before bottling it is usually necessary to rack the wine into new barrels twice or three times to stop secondary fermentations which invariably take place.
Special treatments result in several distinct classes of wine. Thus we can divide wine into red and white as to color. Red wines are produced from colored grapes the color being extracted in the process of fermentation. White wines are made from light colored grapes or if from colored fruit the must is not allowed to ferment on the marc and so extract the color. We may again divide wines into dry and sweet. Dry wines are those in which the sugar is practically all converted into alcohol. Sweet wines are those which retain more or less sugar. These are often fortified by the addition of alcohol. A third division is that of still and sparkling wines. Still wines are those in which the carbonic acid gas formed by fermentation has wholly escaped. Sparkling wines retain a greater or less amount of this carbonic acid gas.
All of the above classes are further divided into well marked types according to their color and taste, their alcoholic content, and the countries in which they are produced. The following are the leading wines made from native grapes: Catawba, Delaware, Concord, Norton’s Virginia, Ives, Scuppernong, Iona, Claret, Port and Champagne. Of these Claret, Norton’s Virginia and Ives are red dry wines. Catawba, Delaware, Iona and Scuppernong may be either dry or sweet white wines. Port is a red sweet wine.
[87] Vol. 22: No. 3:22.
[88] Champagne obtains its name from the fact that it is chiefly produced in the Province of Champagne in France. Its special characteristic is that during fermentation, which is usually brought about in the bottle, the carbonic acid gas generated is absorbed by the wine. When the bottle is opened the gas is disengaged and the wine effervesces or “sparkles”. Good champagne requires grapes of high quality and of special adaptability; the fruit must be well ripened, free from decayed berries, and clean. The first fermentation takes place during a period of several months in the regular receptacles for this purpose after which the wine from several varieties of grapes is blended. Good champagne usually contains some old wine. After bottling, the wine is held at slightly different temperatures for varying lengths of time to secure proper fermentation in the bottle until at the end of several months it is held at a comparatively low temperature in which the bottles remain from three to four years. The bottles must then receive some treatment which will remove the sediment which has been formed by fermentation. This is usually done by placing them in racks cork down at about an angle of 45 degrees or a little more. By dexterously shaking and jarring the bottles the sediment is loosened and deposited in the neck of the bottle. Lastly the sediment is disgorged by skillfully withdrawing the cork, a small portion of the wine being wasted in the operation. The bottles are then filled with a dosage of rock-candy dissolved in an old dry wine, the amount used determining the sweetness of the champagne. The bottles are then corked, wired, capped, labelled and cased, after which the champagne is ready for the market.
[89] Champagne: Decrease in Imports and Increase in Domestic Production, April 25, 1907, p. 427.
[90] Grape juice is made from clean, sound but not over-ripe grapes. The juice is pressed out by machinery in commercial practice but in the home manufacture of the product, the grapes may be pressed by the hands. If a light-colored juice is desired the liquid is extracted without heating the grapes; for a red juice the pulp is heated before pressing and the grapes must be dark in color. In either case the heating is done in a double boiler so that the juice does not come in direct contact with the fire. The proper temperature ranges from 180° F. to 200° F. and must never exceed the 200° mark if the flavor of uncooked grapes is desired. After heating, the juice is allowed to settle for twenty-four hours in a glass, crockery or enameled vessel after which it is carefully drained from the sediment and strained through some sterilized filter. In home practice several thicknesses of flannel, previously boiled, will do for a filter. The liquid is then filled into clean bottles leaving room for expansion in the second heating. The bottled juice is now heated a second time after which it is immediately corked and sealed. The principles involved in making grape juice are the same as those observed in canning fruit and the operation may be varied in the former as it is in the latter if only certain fundamental processes are followed.
[91] A raisin is a dried and cured grape. Raisin-making is a simple process. The grapes are arranged on shallow trays, and placed in the sun to dry, being turned now and then by placing an empty tray on a full one and turning both over after which the top tray is removed. When the grapes are properly dried they are put in bins to sweat preparatory to packing and shipping. The finishing touch in the drying is sometimes given in curing-houses, however, to avoid injury from rain or dust. Seeding, grading, packing and selling are now separate industries from growing and curing. At present all raisins are made from varieties of the Old World grape, no American sort having been found suitable for raisin-making. A variety adapted for making a raisin, something better than simply a “dried grape”, must have a large percentage of sugar and solids, a thin skin, and a high flavor. American grapes lack in sugar content and have a skin so thick and tough that the fruit does not cure properly for a good raisin. The raisin industry in the United States is carried on only in California, the great bulk of the crop coming from the San Joaquin Valley and a few of the southern counties of that State. Formerly the raisins used in this country were wholly imported; now this product of the grape is exported and in increasing quantities. The annual production of raisins is in the neighborhood of 100,000,000 pounds.
[92] According to Bartram, the aborigines of eastern America made raisins from the wild grapes. He describes the process they used as follows: “The Indians gather great quantities of wild grapes which they prepare for keeping, by first sweating them on hurdles over a gentle fire, and afterwards dry them on their bunches in the sun and air, and store them up for provisions.”