vinegar, sour liquid consisting mainly of acetic acid and water, produced by the action of bacteria on dilute solutions of ethyl alcohol derived from previous yeast fermentation. The coloring and flavoring are characteristic of the alcoholic liquor (as cider, beer, wine, fermented fruit juices, solutions of barley malt, hydrolyzed cereals, starches, or sugars) from which the vinegar is made. Vinegar is used as a salad dressing, a preservative, a household remedy to allay irritations, a mild disinfectant, and, in cooking, as a fiber softener. Vinegar has been known from antiquity as a natural byproduct of wine; the name is derived from the French vin aigre [sour wine]. The manufacture as a separate industry began in France in the 17th cent. The wasteful, slow, or natural, process, a spontaneous fermentation in casks half full of beechwood shavings exposed to the atmosphere by bung holes, was superseded in the early 19th cent. by the quick, or generator, method. The generator used in present-day commercial manufacture is usually a tall, truncated cone or vertical, wood tank with a false bottom perforated to admit air that is generally forced through by a blower. The alcoholic solution is allowed to drip through a filling of hard-wood shavings or other material presenting a large surface area. Vinegar made by this method must be aged to remove a natural harshness. It is generally clarified, then pasteurized. Some vinegars are subjected to distillation which removes most of the flavorings other than acetic acid. In another process, the solution is aerated directly by a spinning rotor. The wood shavings are not needed in this case, and the process runs continuously. Acetic fermentation may be impeded by an excessive growth of mother of vinegar, a slimy mass of bacteria, or of the parasitic vinegar eel, a minute, threadlike worm.
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