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FERMENTATION 



CHAPTER I. 



PURE CULTURES OF SYSTEMATICALLY SELECTED 

 YEASTS IN THE FERMENTATION INDUSTRIES. 



i. WHEREIN THE NEW ADVANCE CONSISTS. 



IT will be known to many readers that, in the year 1883 I 

 succeeded in introducing pure cultures of systematically 

 selected yeasts in the brewing industry. My first experiments 

 were carried out in the famous Old Carlsberg Brewery at 

 Copenhagen. When I commenced work in this direction, 

 the yeast question was everywhere a perfect enigma ; it was 

 the weakest point in brewing. When difficulties occurred, a 

 change of yeast was introduced from another brewery, and 

 frequently the yeasts from several breweries were mixed. 

 Sometimes a good result was obtained in this way, some- 

 times also a bad one, and often the result was worse than 

 that which induced the brewer to try a change of yeast. In 

 all cases he was working completely in the dark ; in short, he 

 did not know in the least what he was introducing into the 

 wort. At that time it was not possible to do more than at 

 most detect whether the pitching yeast was contaminated with 

 bacteria and mould fungi ; it was, however, very frequently 

 found that such an examination led to the assumption that a 

 yeast was good, but which nevertheless gave a bad result. I 

 was thus naturally led to the opinion that the secret must 



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