210 ' "DISEASES* OF BEER, 



months in the lager cellar, some of the cask sediment from E (Carlsberg 

 bottom yeast No. i and Sacch. Pastorianus /.), of fairly thin consistency, 

 was introduced into three bottles of ordinary lager beer, one drop being 

 added to each. In this case, therefore, the yeast consisted of a growth 

 which had gone through both primary and secondary fermentation under 

 the conditions obtaining in the brewery. Three bottles which were not 

 infected were kept as a control. After standing for sixteen days no 

 effect had resulted from the infection, either as regards taste and odour or 

 stability of the beer. 



VII. Series of Experiments. Sixteen bottles of lager beer were 

 infected, and three uninfected bottles were kept as a control. For the 

 infection the sediment was used which had formed in bottles which had 

 stood for a long time at the ordinary room-temperature. This beer had 

 been fermented in one case with a mixture of Carlsberg bottom yeast 

 No. i and Sacch. Pastorianus /., and in the other case with a mixture of 

 the same brewery yeast with the above-mentioned variety of Sacch. 

 Pastorianus I. These yeasts had not only carried through the primary 

 fermentation in the fermenting cellar and the normal secondary fermenta- 

 tion in the lager cellar, but had also given rise to a new after-fermentation 

 and to a multiplication of the cells after the beer had been drawn off from 

 the lager casks. Eight bottles were infected with each of the two yeast 

 mixtures, three with one drop, three others with two drops, one with four 

 drops, and one with eight drops of the fairly well diluted yeast. 



The bottles to which eight drops had been added became cloudy from 

 suspended yeast after seven days, those to which four drops had been 

 added were affected in the same way after twelve days, whilst those 

 infected with only one and two drops were still mostly faultless after 

 fourteen days, or at most they showed a faint indication of yeast turbidity ; 

 in short, their stability was practically equal to that of the samples kept 

 for control. As regards odour and taste, no difference could be detected 

 between the infected and the uninfected beer. 



Main Result. The disagreeable odour and the unpleasant 

 bitter taste, communicated to lager beer by the disease we 

 have been discussing, exhibits itself not only in the finished 

 stored beer, but also even in the fermenting wort at the end 

 of the primary fermentation. The experiments have shown 

 that this disease is caused by Sacch. Pastorianus /., and by 

 the varieties which I have obtained from the latter. Strictly 

 speaking, the disease only occurred when the infection had 

 taken place at the commencement of the primary fermenta- 

 tion. The disease, germs must be looked for in the pitching 



