Browsing by Author "Randall, J. H."

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    Relationship between ergosterol concentrations in wine yeast and sugar fermentation at different temperatures
    (South African Society for Enology and Viticulture, 1989) Venter, J. J.; Van Vuuren, H. J. J.; Tromp, A.; Randall, J. H.
    The effect of cellular ergosterol on the fermentation ability of four different Saccharomyces cerevisiae wine yeast strains was studied. F~rmentations were carried out at three temperatures and ergosterol concentrations determined at six fermentation stages. The lower ergosterol concentrations at the higher temperatures are ascribed to the higher growth rate of the yeast cells resulting in a more rapid dilution of the ergosterol. Growth of yeast during fermentation was linked with the ergosterol content of the cells. The ergosterol concentration of the yeast cells was not directly correlated to specific fermentation rates.
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    Relationship between fatty acid concentrations in wine yeasts and sugar fermentation at different temperatures
    (South African Society for Enology and Viticulture, 1989) Venter, J. J.; Van Vuuren, H. J. J.; Tromp, A.; Randall, J. H.
    The effects of temperature and fermentation stage on the cellular concentrations of unsaturated and saturated fatty acids on the fermentation abilities of four different Saccharomyces cerevisiae wine yeasts were studied at three temperatures. The total unsaturated and saturated fatty acid concentrations were determined at six fermentation stages. Unsaturated fatty acid concentration decreased and the concentration of saturated fatty acids increased as fermentation proceeded. Saturated fatty acid concentration of the yeast cells correlated positively with high specific fermentation rates during the later stages of fermentation in contrast to the belief that fluid membranes with high unsaturated fatty acid concentrations enhance ethanol tolerance and, therefore, fermentation performance.