Turning of Wine and Beer 459 



of the container. Wine thus turned always contains 

 considerable quantities of lactic acid produced by cer- 

 tain lactic-acid ferments. The disease is most liable to 

 occur in wine made from musts that are not, in all 

 respects, normal, particularly from those whose acidity 

 is below the average. 



The turning of beer is characterized by a gradually 

 increasing turbidity and the development of unpleasant 

 tastes and odors. A deposit is also formed in the course 

 of time. An organism isolated from samples of turned 

 beer and named Saccharobacillus 

 pasteurianus has been found to 

 cause the disease when inoculated 

 into sound beer. The alcohol in 

 the beer does not prevent the de- 

 velopment of the organism except 

 when present in amounts greater 

 than 7 per cent. It seems, also, F i g . 70. Lactic-acid bac- 

 that it is affected by the composi- souring^of d'StiiierJ 

 tion of the wort, since a larger pro- ??2,ooo; I1 (6) h x 2,700 

 portion of hop extract either pre- (Emmerimg.) 

 vents or retards its growth in the beer. The brewers 

 guard against the turning of their product by careful 

 refrigeration and resort to pasteurization when the beer 

 is intended for export to warm countries. For certain 

 varieties of beer, the lactic fermentation in beer wort 

 is encouraged, as is done, for instance, in the brewing 

 of "Weissbier" (white beer). 



Ropiness in wine. Another disease that leads to the 

 development of ropiness in wine was investigated by 

 Pasteur in 1861. He and other investigators after him 



