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STRAINS OF YEAST LETHAL TO BREWERY YEASTS
Author(s) -
Maule A. P.,
Thomas P. D.
Publication year - 1973
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1973.tb03515.x
Subject(s) - yeast , fermentation , biology , sugar , saccharomyces cerevisiae , microbiology and biotechnology , food science , chemistry , biochemistry
Strains of yeast that are lethal to brewery ale and lager yeasts have been isolated from production‐scale two‐stage stirred continuous fermentors. These strains release a “killer” factor which is highly active in the pH range 3.8–4.2. When the level of infection reaches 2% the concentration of killer factor is sufficient to give a selective advantage in continuous fermentation, whereupon the proportion of killer yeasts rises and the brewery yeast is rapidly killed. The beer acquires a characteristic off‐flavour which has been described as “herbal/phenolic”. Both flocculent and non‐flocculent killer strains have been found and these show the characteristics of Saccharomyces cerevisiae but appear to ferment additional wort sugar(s), have an abormally small cell‐size and are pleomorphic in mixed culture.