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SOME CONSIDERATIONS OF THE FLOCCULATION CHARACTERISTICS OF ALE AND LAGER YEAST STRAINS *
Author(s) -
Stewart G. G.,
Russell I.,
Garrison I. F.
Publication year - 1975
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.2050-0416.1975.tb03686.x
Subject(s) - flocculation , yeast , inducer , biochemistry , yeast extract , chemistry , agglutination (biology) , cell wall , ammonium , chromatography , saccharomyces cerevisiae , biology , fermentation , organic chemistry , genetics , antigen , gene
While some ale yeast strains are able to flocculate when cultured in a defined medium of glucose, ammonium salts, vitamins and ions, others require the presence of a nitrogen‐containing inducer in the growth medium. On the other hand, all flocculent lager strains examined to date are able to flocculate after being cultured in a defined medium and do not appear to require the addition of inducer material to the growth medium. The inducer material present in wort has been identified as peptide. By the use of ion exchange chromatography the peptide fraction that induces flocculation has been found to contain a high level of acidic amino acid residues with a very similar structure to that reported for the α‐factor involved in sexual agglutination of haploid α and a cells of Sacch. cerevisiae . Studies on the adsorption of Ca ++ ion by the cell wall failed to reveal any significant differences in total uptake between flocculent and non‐flocculent cultures. It would appear that Ca ++ ions are bound less tightly by non‐flocculent cells than by flocculent cells. The contribution of calcium to flocculation is not the absolute amount of this ion adsorbed by the yeast cell wall but rather the stereo‐specific manner by which it is bound, i.e ., its position relative to the three‐dimensional structure of the yeast cell wall.