VINEGAR � ACETUM
United States Dispensatory 1926
In the quick German process for making vinegar a mixture of one part of 80 per cent, alcohol, four or six parts of water, and one-thousandth of honey or extract of malt, at a temperature of 24� C. to 35� C., is allowed to percolate through beech shavings, previously steeped in vinegar, and contained in a deep oaken tub, in which is a wooden diaphragm perforated with numerous small holes, loosely filled with packthread about six inches long. It is essential to the success of the process that a current of air shall pass through the tub. In order to establish this current, eight equidistant holes are pierced near the bottom of the tub, forming a horizontal row, and four glass tubes are inserted vertically in the diaphragm, of sufficient length to project above and below it. The air enters by the holes below, and passes out by the tubes. Although the air is necessary for the furnishing of oxygen, acetification consisting chiefly in the oxidation of the alcohol, the beech shavings and similar articles chiefly aid in the process by affording surface upon which the mycoderms can grow. During the process the temperature rises to 37� C. or 40� C., and remains nearly stationary while the process is going on favorably. The liquid is drawn off by a discharge pipe near the bottom, and must be passed three or four times through the tub before the acetification is completed, which generally occupies from twenty-four to thirty-six hours. According to Wimmer, pieces of purified charcoal, about the size of a walnut, may be advantageously substituted for the beech shavings in the process.
In 1862, Pasteur substituted for the German process the sowing of the mycoderm upon the surface of a mixture of wine and vinegar, or of water, alcohol (2 per cent.), and acetic acid (1 per cent.) adding alcohol daily in small quantities after about half that contained in the original liquid had been converted into acetic acid, until a vinegar of sufficient strength was produced. The French process was improved in 1869 by Laugier, and it was subsequently further elaborated by Emanuel Wurm. (For details, see P. J., xi, 133.)
In England, vinegar is made from the infusion of malt. The fermented wort is caused to fall in a shower upon a mass of fagots of birch twigs occupying the upper part of a large vat, and, after trickling down to the bottom, is pumped up repeatedly to the top, to be again allowed to fall, until the acetification is completed. This mode of oxidizing the alcohol in the fermented wort has the advantage of rendering insoluble certain glutinous and albuminous principles, which, if not removed, would cause a muddiness in the vinegar and make it liable to spoil. In the United States, vinegar is largely made by the German method of oxidizing very diluted alcohol, and is called white vinegar; it is often prepared from cider.
Cider vinegar. The cider is placed in barrels (with their bung holes open) which are exposed during the summer to the heat of the sun. The acetification is completed in the course of about two years. The process of the fermentation, however, must be watched, and as soon as perfect vinegar is formed, it should be racked off into clean barrels. Without this precaution, the acetous fermentation would run into, the putrefactive, and the vinegar spoil. Cider vinegar contains no aldehyde. It contains malic acid, and therefore yields a precipitate with lead acetate. The absence of such a precipitate indicates that the alleged cider vinegar is a manufactured substitute, although a fictitious article might yield a similar precipitate. Cider or apple vinegar is also made by the quick process described above. Much commercial vinegar is made from the apple cores, skins and other waste from the dried apple and pectin industry. Vinegar may be clarified, without impairing its aroma, by throwing about a tumblerful of boiling milk into from fifty to sixty gallons of the liquid, and stirring the mixture. This operation also makes red vinegar pale.
The series of changes which occur during the acetous fermentation is called acetification. The following equations represent this change:
C2H6O + O = C2H4O + H2O O = C2H4O2
Vinegar, when good, is of an agreeable, penetrating odor, and a pleasant acid taste. According to Magnes-Lahens, wine vinegar always contains a little aldehyde. The better sorts of vinegar have a grateful aroma, probably due to the presence of an ethereal substance, perhaps acetic ether. The color of vinegar varies from water white to deep red. When long kept, especially if exposed to the air, it becomes ropy, acquires an unpleasant odor, putrefies, and loses its acidity. The essential ingredients of vinegar are acetic acid and water; but, besides these, it contains various other substances, derived from the particular vinous liquor from which it may have been prepared.
Malt Vinegar (Acetum Britannicum) has a brown color, and a sp. gr. from 1.006 to 1.019. The strongest kind, called proof vinegar, contains from 4.6 to 5 per cent, of acetic acid. That of British manufacture usually contains sulphuric acid, which the manufacturer is allowed by law to add in a proportion not exceeding one part in a thousand; but if the vinegar be properly made it does not require to be thus protected. Malt Vinegar is " a liquid of a brown color and peculiar odor. Specific gravity 1.017 to 1.019. 445.4 grains by weight (1 fluidounce) of it require about 402 grain-measures of the volumetric solution of soda for their neutralization, corresponding to 5.41 per cent, of real acetic acid, HC2H3O2. If ten minims of solution of barium chloride be added to a fluidounce. of the vinegar, and the precipitate, if any, be separated by filtration, a further addition of the test should give no precipitate. Sulphuretted hydrogen caused no change of color." Br., 1885.
Wine Vinegar (Acetum Gallicum) is nearly one-sixth stronger than pure malt vinegar. It is of two sorts, the white and the red, according as it has been prepared from white or from red wine. White wine vinegar is usually preferred. Red wine vinegar may be deprived of its color, and rendered limpid, by being passed through animal charcoal. Under the name of wine vinegar or white wine vinegar the so-called distilled vinegar is sometimes sold. This is made, not by distillation of vinegar as the name indicates, but by the distillation of a weak alcoholic liquid produced by the fermentation of molasses with yeast and the subsequent acetification of the weak alcohol by percolation through beech wood shavings impregnated with mycoderma aceti. The best test for the detection of free inorganic acids is a weak solution of methyl violet which turns green in the presence of free inorganic acids, but remains unaffected by organic acids.
Distilled Vinegar (Aceturn Destillatum; Vinaigre distille, Oxeolat simple, Fr.; Destillirter Essig, G.) was official in the U. S. Pharmacopoeia, 1870, and was prepared by obtaining seven pints of distillate from eight pints of vinegar placed in a glass retort, the one pint left in the retort retaining the fixed impurities, salts, etc. One hundred grains should saturate not less than seven and six-tenths grains of potassium bicarbonate. The principal foreign substances which vinegar is liable to contain are sulphuric and sulphurous acids, and copper and lead, derived from improper vessels used in its manufacture. Tin has been found in it after standing a short time in tin vessels. The testing of vinegar for genuineness and purity involves so many complex factors that a work on food analysis, such as that of Leach, should be consulted.
Vinegar is at present used as a medicine only for its local astringent
properties, and in the form of an enema diluted with three times its
bulk of water to kill seat worms. In the dermatitis produced by exposure to
the sun, made into a paste with glycerin, bismuth, and starch, it is very
effective. In hematemesis one ounce to a tumbler of water often acts very
advantageously, and may be taken freely. At one time vinegar was largely
used in pharmacy as a menstruum, but on account of its tendency to undergo
decomposition it has been replaced by diluted acetic acid in both the
American and British Pharmacopoeias.
Aromatic Vinegar (B.P.C. 1934). Acid.
Acet. Aromat.; Gewiirzessig.
Toilet Vinegar (B.P.C. 1934). Acetum
Odoratum; Acetum Profumatum.
Please note that the Martindale�s is a very small extract from the Monograph entitled Organic Acids.
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