THE MANUFACTURE OF VINEGAR 549 



These methods make use of a barrel filled partially or wholly with 

 beech chips and half filled with the liquid to be acetified. By rotating 

 the barrel at short intervals the liquid trickles repeatedly over the chips 

 and, with proper aeration, the acetification is rapid and complete. 



After-treatment. — Alcohol vinegars require little treatment. 

 They should be filtered and are usually colored slightly with caramel. 

 Being Uttle more than dilute solutions of acetic acid without ethers or 

 bouquet, there is no object in aging them. 



Wine and cider vinegars, for the best results, require aging and 

 careful treatment. They should be filtered and pasteurized as soon as 

 made and stored in clean casks which are well bunged and kept con- 

 stantly full in a cool place of even temperature. If too dark in color, 

 they may be decolorized with pure animal charcoal carefully extracted 

 with acids and water. 



Before using or bottling, the vinegar should be fined with isinglass 

 (see page 523). 



Diseases 



The most troublesome pest of vinegar factories is a minute nema- 

 tode, the Anguillula aceti or vinegar eel. It often develops around the 

 edges of the surface of the liquid in vinegar barrels and in the acetify^ 

 ing columns and, if neglected, may cause putrefaction and spoiling of 

 the vinegar. Frequent and thorough cleaning of all apparatus, pasteur- 

 ization of hquids and light sulphuring of empty casks will prevent its 

 development. The vinegar eels are easily killed by heating the vinegar 

 to 50°. They "may be removed by filtration or fining. 



Microscopic mites are sometimes troublesome in neglected factories. 

 They can be reduced by the methods recommended for vinegar eels 

 and their entrance into the barrels or acetifying columns prevented by 

 painting a ring of turpentine or some viscid substance around each air 

 hole. 



Vinegar flies (Drosophylla cellaris) are often troublesome, but can be 

 excluded by proper screening of buildings and barrels. 



Bacteria other than acetic may develop in vinegar and some of 

 them may depreciate its quality. These have been httle studied but 

 the most harmful seem to be anaerobic forms which develop in the 

 lower parts of the liquid protected from oxygen by the screening film 



