THI: PREPARATION OF FARM PRODUCTS. 28/ 



would be obtained by the use of a single type of the bacterium, 

 and by the maintenance of the conditions under which this 

 type could grow the best. When there is in the " mother" a 

 miscellaneous mixture of the various forms, of a wholly un- 

 known nature, it is evident that no conditions can be main- 

 tained which will produce the best results. 



THE USE OF PURE CULTURES. 



In the manufacture of vinegar, by the processes now in use, 

 there is always a considerable loss of alcohol and a smaller 

 yield of acetic acid than there should be from the quantity of 

 alcohol used. It is well recognized that this is to be accounted 

 for largely by the fact that the fermenting organisms are not all 

 of one species, and that the " mother " is commonly a mixture 

 of several varieties, each demanding different conditions for its 

 proper and most efficient action. It is inevitable that such 

 chance methods should not result most efficiently. 



For some time the bacteriologists have been insisting that 

 the adoption of pure cultures in vinegar-making would bring 

 about a considerable improvement in the results. Every one 

 recognizes what a revolution has been brought about in the 

 brewing industry by the introduction of pure cultures of yeasts 

 into that fermentative process. It is perfectly possible that a 

 similar application of pure cultures of acetic bacteria should be 

 made in the vinegar industry, and it is quite probable that 

 such an introduction would result in an improvement in the 

 manufacture and in a considerable saving of the material now 

 lost. 



But hitherto there has been no considerable application of 

 pure cultures to vinegar-making. To obtain absolutely pure 

 cultures is a difficult matter, and to keep them pure from sub- 

 sequent contamination is more difficult still. Vinegar-makers 

 have not found the advantages derived from such methods 

 sufficient to pay for the labor and trouble of applying them, 



