The effects of osmotic pressure and ethanol on yeast viability and morphology.

Patricia L. Pratt, James H. Bryce, Graham G. Stewart

    Research output: Contribution to journalArticle

    Abstract

    The selection of a brewing yeast strain with the required fermentation and recycling characteristics is critical. The yeast strain will influence the rate and extent of fermentation, the flavour characteristics and the overall quality and stability of the finished beer, and consequently, the economic viability of the brewery. Since high gravity worts can have a deleterious effect on yeast fermentation performance, it is imperative that the strain selected be suitable for this environment, which includes a capacity to withstand high osmotic pressures and elevated ethanol levels. Under controlled in vitro osmotic and ethanol induced stresses, there was a decline in mean cell volume in both lager and ale yeast strains. Whilst significant reductions in viability were observed in the lager strains, the ale strains studied were not affected. Cell surface investigations revealed shrinkage of the yeast cells and crenation of the outside envelope under both stresses, although exposure to ethanol had a more marked effect on the yeast cell surface than sorbitol-induced elevated osmotic pressure.

    Original languageEnglish
    Pages (from-to)218-228
    Number of pages11
    JournalJournal of the Institute of Brewing
    Volume109
    Issue number3
    Publication statusPublished - 2003

    Fingerprint

    Osmotic Pressure
    Ethanol
    Yeasts
    Fermentation
    Hypergravity
    Erythrocyte Indices
    Sorbitol
    Recycling
    Economics

    Keywords

    • Cell viability
    • Cell volume
    • Ethanol
    • High gravity wort
    • Osmotic pressure

    Cite this

    Pratt, Patricia L. ; Bryce, James H. ; Stewart, Graham G. / The effects of osmotic pressure and ethanol on yeast viability and morphology. In: Journal of the Institute of Brewing. 2003 ; Vol. 109, No. 3. pp. 218-228.
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    Pratt, PL, Bryce, JH & Stewart, GG 2003, 'The effects of osmotic pressure and ethanol on yeast viability and morphology.', Journal of the Institute of Brewing, vol. 109, no. 3, pp. 218-228.

    The effects of osmotic pressure and ethanol on yeast viability and morphology. / Pratt, Patricia L.; Bryce, James H.; Stewart, Graham G.

    In: Journal of the Institute of Brewing, Vol. 109, No. 3, 2003, p. 218-228.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - The effects of osmotic pressure and ethanol on yeast viability and morphology.

    AU - Pratt, Patricia L.

    AU - Bryce, James H.

    AU - Stewart, Graham G.

    PY - 2003

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    AB - The selection of a brewing yeast strain with the required fermentation and recycling characteristics is critical. The yeast strain will influence the rate and extent of fermentation, the flavour characteristics and the overall quality and stability of the finished beer, and consequently, the economic viability of the brewery. Since high gravity worts can have a deleterious effect on yeast fermentation performance, it is imperative that the strain selected be suitable for this environment, which includes a capacity to withstand high osmotic pressures and elevated ethanol levels. Under controlled in vitro osmotic and ethanol induced stresses, there was a decline in mean cell volume in both lager and ale yeast strains. Whilst significant reductions in viability were observed in the lager strains, the ale strains studied were not affected. Cell surface investigations revealed shrinkage of the yeast cells and crenation of the outside envelope under both stresses, although exposure to ethanol had a more marked effect on the yeast cell surface than sorbitol-induced elevated osmotic pressure.

    KW - Cell viability

    KW - Cell volume

    KW - Ethanol

    KW - High gravity wort

    KW - Osmotic pressure

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    EP - 228

    JO - Journal of the Institute of Brewing

    JF - Journal of the Institute of Brewing

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