r^^o 



51 



STATE BOARD OF AGRICULTURE. 



desirable ones Avhich also use sugar as food, and are favored by low 

 temperatures. 



Other 'bacteria may produce injurious changes at the beginning before 

 the vinegar bacteria have taken possession of the liquid. Their action 

 is prevented by either adding 10 per cent of good vinegar, or by prompt 

 starting of the acetic fermentation by means of a vigorous culture of 

 vinegar bacteria. 



Injurious bacteria may also attack the vinegar towards the end of the 

 fermentation, producing putrid odors. These bacteria are prevented 

 from exerting a harmful effect by promptly removing the vinegar to the 

 storage casks as soon as the acetic fermentation is complete, by pasteur- 

 izing it at 140 degrees F., or by running it into barrels in "which a stick 

 of sulphur has been burned. 



Controlling the vinegar fermentation : The vinegar fermentation is 

 usually left to chance by the amateur vinegar maker. The commercial 

 butter-maker nowadays would quickly lose not only his prestige but his 

 income if he went back to the old method of depending on chance for 

 the flavor of his product. Modern commercial butter depends upon its 

 uniform high quality for its market value. This is due to its uniform 

 pleasant acid flavor which is produced by controlling the acid fermenta- 

 tion of the cream by the addition of pure cultures of bacteria selected 

 for this very purpose. 



Fig. 7. Pure Cultures for Vinegar Making. Ttiese pure cultures are growing in eterile cider. 



By adding pure cultures which consist of enormous numbers of the 

 selected germs, so many desirable germs are ad^ed ^h^t they crowd out 



