VINEGAR (OF., Fr. vinaigre, from tin, from Lat. rinum, wine aigrc, sour, sharp, keen, from Lat. aecr, sharp, keen). A sour liquid ob tained by acetic fermentation of alcoholic prod ucts, usually wine, cider, or malt, used chiefly for culinary purposes and for preserving. The active principle of vinegar is acetic acid. which varies in amount from 2 per cent, to 10 per cent. and even more the distinctive flavor and aroma are derived from the materials from which it is made or, in artificial products, from added sub stances. Small amounts of alcohol, and inciden tal products of fermentation, are usually present. together with extractive matters depending upon the nature of the materials from which it is made. Cider vinegar contains traces of =lie acid, the acid of the apple. Formerly some min eral acid, usually sulphuric, was added to vin egar as a preservative and to reinforce it, but this practice is now regarded as an adulteration. In Europe wine and spirit vinegars are most commonly used, that from white wine being most highly esteemed; in Great Britain malt vinegar is extensively used; in the United States eider vinegar is preferred.
There are two methods of making vinegar—the slow or natural fermentation and the "quick process." In both of these the production of acetic acid from the alcohol is effected through oxidation by the agency of micro-organisms, which are supplied in the lees or the 'mother of vinegar.' The latter is a soft, felted mass, commonly forming a scum on the surface of the fermenting liquid. Tt contains an aggregation of microorganisms, the essential ones being formerly supposed to belong to one species, known as Mycoderma aced. They are now known to belong to the general group Bacteria and to include sonic half dozen or more species. These vary in their growth. some producing their max imum effect more quickly than others. The process as ordinarily carried on in casks or bar rels is quite slow, requiring several weeks al a favorable temperature; but in the quick vin egar process the change is accomplished in a few hours.
The quick process consists in bringing tloi al coholic liquid into intimate contact with the air by means of beechwood shavings, which are placed in a tall vessel called a generator. and inoculated with warm vinegar to furnish the micro-organisms and to start the process. The generator is usually a tall ssooden cask. smaller at the top than at the bottom, and divided into three horizontal sect ions. one of the dividing disks being near the top, and the other a false bottom. Several tubes that serve as air through the upper disk, which is also perforated with numerous small holes, through which pack threads extend. The central or mail] part of the generator is filled with beech-shavings. The alcoholic liquid, first heated to about C. F.), and introduced at the upper part of the apparatus, trickles slowly down the threads, diffuses over the chips, coining in con tact with the rising current of air, and collects in the bottom of the cask, where it is drawn off by a siphon pipe. It is necessary for the
liquid to pass through the cask several times, or through several casks, before acetification is completed, the entire operation requiring from 24 to 36 hours.
In the preparation of wine vinegar full-bodied wines are chosen, and if they contain more than 10 per cent. of alcohol they are usually diluted or mixed with weaker wines. They are then treated by the quick process or fermented in scalded casks filled partly full, for a period of about two weeks, by the slow process, when a portion of the vinegar is drawn off and more wine added, this being repeated periodically. Spirit vinegar is made by distilling a fermented mash of grain so as to obtain a very dilute al cohol, and converting this without rectification into vinegar by the quick method. It is often colored with caramel to simulate cider or wine vinegar. In the preparation of malt vin egar an infusion of malt with a suitable quan tity of yeast is fermented briskly for about 40 hours, to change the sugar into alcohol. The ex tract is then filtered and allowed to settle, after which it may be treated by the quick vinegar process, or acetified in large casks lying on their sides in a room at a temperature of about C. F.). The bung-holes of the casks are left open, and at each end near the top an opening is made so as to permit the circulation of air. The operation is begun in the spring and finished in about three months. Cider vinegar is prepared by allowing fresh cider to ferment in barrels or casks until the proper percentage of alcohol has been formed. IT is then acetified, usually by the slow process, in a warm room.
The employment of the quick process in vin egar-making enables a more uniform article to be produced with certainty Ilan by the slow fer mentation. The latter is more or less haphazard, depending upon the exact kinds of organisms present. and results in considerable loss of al cohol as well as a smaller yield of acetic acid. This has suggested the use of pure cultures of vinegar bacteria for the fermentation, as is done in beer and wine making; but the difficulties in procuring these pure cultures and in managing the process have been found to outweigh the ad vantages from their use. In addition to being a condiment, vinegar is used extensively in pick ling and preserving various kinds of foods, and has an important action in softening the fibres of hard meats and the cellulose of green vegetables. It is also occasionally employed in medicine as a cooling astringent and as a solvent for various drugs, such as lobelia and are called vinegar of lobelia, of opium, etc. The term aromatic vinegar is ap plied to ',reparations of strong acetic acid hold ing in solution various aromatic oils, such as hergauot, di Wes, In Vender, neroli, etc., with eamphor, forming a fragrant and volatile per fume. Consult Cardner, Acetic Acid, Thieriot., Muni, .Intnionia, etc. (Philadelphia, 1885) ; Drannt..1 Practical Treatise on the Ilanuffietare of Vinegar and _Icetatcs, etc. (Philadelphia., 1890). See ACETIC ACID.