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Determinants of flocculence of brewer's yeast during fermentation in wort
Author(s) -
Straver Marika H.,
Aar Paul C. V. D.,
Smit Gerrit,
Kijne Jan W.
Publication year - 1993
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.320090509
Subject(s) - yeast , fermentation , ergosterol , saccharomyces cerevisiae , flocculation , brewing , cell , biology , biochemistry , food science , cell growth , chemistry , organic chemistry
Ability of Saccharomyces cerevisiae MPY3 cells to flocculate during fermentation in wort was found to be triggered after growth limitation by oxygen shortage and to coincide with a sharp increase in cell surface hydrophobicity of the cells. Presence of oxygen in the pitching wort influenced final cell number, flocculence of the cells and cell surface hydrophobicity. Flocculation ability of cells grown in air‐depleted pitching wort was hampered, concomitant with a decrease in final cell number and in final cell surface hydrophobicity. Addition of ergosterol and Tween 80 to air‐depleted wort restored normal growth of the cells as well as flocculation ability and the increase in cell surface hydrophobicity. The same parameters increased in value after addition of ergosterol and Tween 80 to a fermentation with air‐saturated pitching wort. Hydrophobicity of a non‐flocculent mutant of S. cerevisiae strain MPY3, fermenting in air‐saturated pitching wort, did not increase at cell division arrest. These results support the hypothesis that cell surface hydrophobicity is a major determinant for yeast cells to become flocculent, and suggest that shortage of sterols and unsaturated fatty acids precedes flocculence under brewing conditions.