ACTION OF FUNGI ON CARBOHYDRATES, ETC. 261 



The different action of the Saccharomycetes on the same 

 nutritive liquid (wort or must) under identical conditions, has 

 been further studied by Borgmann, Amthor, and Marx. 



According to Borgmann, the chemical reactions brought 

 about in wort by the two Carlsberg bottom yeasts, No. 1 and 

 No. 2, show a striking difference. These two species which 

 had been in use for some time in the fermenting room, and 

 were still practically pure were employed for pitching two 

 fermenting vessels containing wort from the same brew ; the 

 fermentation took place under conditions which enabled a 

 true comparison to be made, and the resulting beer was stored 

 as usual. The differences in the chemical reaction were 

 especially noticeable in the proportion of free acid. Thus : 



No. 1. No. 2. 



Free acid (calculated as lactic acid), . 0'086 0'144 per 100 c.c. 



Glycerine, 0'109 0'137 



As a result of these experiments, Borgmann pointed out 

 that the ratio between the alcohol and glycerine in these two 

 beers differs from that previously found in beer, the ratio 

 obtained from previous analyses being : 



Alcohol. Glycerine. 



Maximum, 100 5*497 



Minimum, 100 4-140 



Whilst the Carlsberg beers gave the following ratios : 



Alcohol. Glycerine. 



No. 1, 100 2-63 



No. 2 100 3-24 



It must be admitted, as Borgmann observed, that good 

 beer may be produced by a method not open to criticism, in 

 which the ratio of alcohol to glycerine may sink below the 

 previously-admitted minimum. 



A series of the eight different species of Saccharomyces, and 

 amongst them six culture yeasts, all in absolutely pure cultures, 

 were examined by Amthor with reference to their chemical 

 action on beer-wort. The fermentations were conducted in 

 Pasteur flasks of one litre capacity under identical conditions, 

 and formed two series, one corresponding to the primary 

 fermentation in the brewery, and the other to the secondary 



