ACTION OF FUNGI ON CARBOHYDRATES, ETC. 2(55 



Both the percentage of nitrogen and of ash proved to 

 be different in wines fermented with the three kinds of 

 yeast. 



The acid content was highest in the wines fermented with 

 Wiirzburger yeast, and practically equal for the other two 

 kinds. 



In accurate comparative experiments, a large number of 

 species differed widely with respect to the amount of alcohol 

 produced in the liquid ; those yeasts having the shortest 

 fermentation period yielded the smallest percentage of alcohol, 

 and conversely. 



With regard to the bouquet in wine, Wortmann and Miiller- 

 Thurgau distinguished between that which originates in the 

 grape " grape bouquet " and that which is produced as a 

 result of the activity of yeast " fermentation bouquet." In 

 some wines the grape bouquet is so strongly developed that 

 the fresh bouquet formed by the action of yeast on some of 

 the substances present in the grape plays only a subordinate 

 part in determining the character of the wine. In other wines 

 where the grape bouquet is not so strongly developed the 

 fermentation bouquet may have a great influence on its 

 character. The result of applying a pure culture of a wine 

 yeast will, therefore, differ with different wines. In the first 

 group of wines the influence must be regarded as an indirect 

 one in that the pure culture suppresses foreign organisms, 

 which might mask the true grape bouquet, whereas the fer- 

 mentation bouquet will have but little influence on the wine. 

 In the fermentation of such wines the best results will be 

 obtained by using yeasts from the locality. It is quite other- 

 wise with the second group of wines. With such musts 

 possessing no outstanding characteristics, the application of 

 specially selected yeasts will exercise a directly favourable 

 influence on the flavour and on the whole character of 

 the wine. The long experience of the author has fully 

 established the fact that both the quantity and the variety 

 of the fermentation bouquet may be increased by such 

 means. 



The fermentation bouquet differs with each yeast species, 

 but neither its quality nor quantity stands in direct relation- 



