184 



WINE, CIDER AND VINEGAR 



Fig. 268. The cutting or 

 grinding mechanism of 

 a cider mill. 



organisms which are abundant in the soil and on 

 the surfaces of the fruits themselves. 



For certain uses, or when only the acidity char- 

 acteristic of the acetic acid is desired, " vinegar 

 essence," containing high percentages of acetic 

 acid in a relatively pure 

 state, may be made from 

 certain kinds of wood by 

 a process of distillation. 

 Undoubtedly much of the 

 cheaper grades of vinegar 

 for table use has its origin 

 in this way. It is cheaper 

 than the production of the 

 acetic acid by fermenta- 

 tion. By a proper admix- 

 ture of ethers and flavor- 

 giving bodies a solution 

 may be made which simu- 

 lates the product of the 

 fermentation process, but never has the " bouquet " 

 and the fine quality which characterizes the latter 

 kind. 



Fermentation vinegar. 



Fermentation vinegar, or that properly used as 

 a condiment, may be prepared from numerous 

 kinds of alcoholic solutions, but especially from 

 cider, wine or beer, through the agency of a class 

 of bacteria generally known as the acetic bacteria. 

 These little organisms have the power, under 

 proper conditions of temperature and aeration, of 

 oxidizing the alcohol to acetic acid and water in 

 accordance with the chemical equation 



C2H5OH + 02 = CH3.COOH + H2O 



Probably an intermediate substance, aldehyde, is 

 formed sometimes, although it is not certain that 

 this is always the case. 



In order to have this reaction proceed it is 

 necessary to have (1) a lively and suitable micro- 

 organism ; (2) solutions of relatively weak alcohol, 

 as the organisms are poisoned by amounts much 

 over 10 per cent, and, indeed, will not work rapidly 

 in solutions approaching this concentration ; (3) 

 an abundance of air ; and (4) a well-regulated and 

 favorable temperature. 



The acetic group of bacteria comprises a number 

 of species, perhaps twenty of which have been iso- 

 lated and described, all characterized by their power 

 of oxidizing alcohol to acetic acid almost in accor- 

 dance with the chemical equation given above. 

 They are also to be recognized by the fact that they 

 require air for development and form large masses 

 or scums of gelatinous character (zooglcea), the so- 

 called " mother of vinegar." The formation of these 

 masses is progressive, and goes on so long as the 

 food and other conditions remain suitable for the 

 organisms. The cell wall of each individual swells 

 to a large size and becomes practically fused with 

 the cell wall of its neighbor, until huge masses of 

 jelly-like consistency, and containing millions of 

 bacterial cells, are produced. 



The upper temperature limit of growth of the 

 organisms is about 42° C, the lower limit about 



5° to 6° C, while the action is manifested most 

 strongly at about 34° C, a fact that is of great 

 importance in the production of vinegar. 



Methods of making vinegar. 



Two distinct methods of vinegar manufacture 

 have been developed. One of these is practically 

 an imitation of what might be called the natural 

 acetic fermentation, while the other is a fermenta- 

 tion carried out under forced draught. The former 

 is generally called the French or Orleans method 

 because it was and still is used in making vinegar 

 from wine ; while the latter is known as the 

 "quick process " or the German process. 



The custom prevailing among farmers in this 

 country is, in many respects, similar to the Orleans 

 method. It is well known that if a barrel of cider 

 be freely opened so that air comes in intimate con- 

 tact with the cider it " turns," especially if kept 

 at a moderately warm temperature. The explana- 

 tion of this is that the organisms, which were 

 present in large numbers on the skins of the fruit, 

 gain entrance to the cider, but so long as there is 

 no free access of air they develop but slowly, if at 

 all. Given access to air and a favorable tempera- 

 ture, they immediately begin the oxidation of the 

 alcohol to acetic acid, and the cider turns slowly 

 to vinegar. 



In the Orleans method this process is varied 

 somewhat. Vats or barrels having free access of 

 air are filled about a quarter full of good vinegar. 

 This supplies the "culture." An equal amount of 

 wine is then added and the alcohol oxidized. At 

 the end of a few days another quantity of wine is 

 added and finally a third. The vat is now full, and 

 after the oxidation of the alcohol has become essen- 

 tially complete, three-quarters of the vinegar is 

 removed and the process re- 

 peated over and over. " 

 method ex- 

 cellent vine- 

 gar may be 

 made, but with con- 

 siderable expenditure 

 of time. 



The "quick pro- 

 cess " is based on the 

 facts previously 

 noted, — namely, the 

 rapid oxidation at the 

 optimum temperature 

 of 34° G. and neces- 

 sity for large amount 

 of air. In the " quick 

 process " large tanks, 

 technically known as 

 "generators," are em- 

 ployed. These are in 

 the form of truncated 

 cones, six to twenty feet high, with a false bottom 

 near the lower end and a perforated horizontal 

 disk or false head near the upper end. The space 

 between is filled with some substance which is 

 without action on either solution or bacteria and 

 which will supply a large amount of surface to the 



Fig. 269. Farm cider press. 



