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FERMENTATION VELOCITY OF YEASTS II. A STUDY OF THE FERMENTATION VELOCITIES OF A SERIES OF BOTTOM AND TOP FERMENTATION BREWERY YEASTS
Author(s) -
Thorne R. S. W.
Publication year - 1954
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.2050-0416.1954.tb06230.x
Subject(s) - fermentation , yeast , strain (injury) , saccharomyces cerevisiae , nitrogen , food science , biology , saccharomyces , chemistry , biochemistry , organic chemistry , anatomy
The fermentation velocities of 20 strains of brewery bottom yeasts ( Saccharomyces carlsbergensis ) and 10 strains of brewery top yeasts ( Sacch. cerevisiae ) were estimated, five separate cultures of each strain being examined. It was found that fermentation velocity is an extremely inconstant property of yeasts; not only may it vary greatly from one strain to another, but even different cultures of a particular strain can give very different results. It is shown, however, that the fermentation velocity of a yeast is a function almost solely of its nitrogen content, the relation between mean fermentation velocity, φ, and nitrogen content, N , being of the form: φ = c ( N — N o ), where N o is a threshold value of nitrogen content which appears to be constant for all yeasts, while c is a factor characteristic of the strain. For a given nitrogen content, bottom yeasts are, in general, much faster fermenters than top yeasts. Other factors can play no more than a very minor part in determining fermentation velocity; in particular, fermentation velocity appears to be quite unrelated to the flocculence of the yeast concerned.