The Yeast Vacuole – A Scanning Electron Microscopy Study During High Gravity Wort Fermentations
Patricia L. Pratt1,2, James H. Bryce2 and Graham G. Stewart2,3
1 Molson Coors Brewing Company, Golden, CO 80401.
2 International Centre for Brewing and Distilling, School of Life Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, Scotland.
3 Corresponding author. E-mail: g.g.stewart@hw.ac.uk
J. Inst. Brew. 113(1), 55–60, 2007 | VIEW ARTICLE
ABSTRACT
The yeast vacuole has been shown to exhibit morphological responses to environmental conditions when exposed to worts of different gravity during fermentation. Marked effects of high gravity wort (20° Plato) on yeast morphology compared to more conventional wort gravity (12° Plato) were observed. High gravity worts caused vacuolar enlargement compared to conventional gravity wort. These results suggested that yeast cells experienced severe alterations with the vacuolar tonoplast when exposed to high osmotic pressure and elevated levels of ethanol.
Key words:
High gravity wort, ethanol, morphology, osmotic pressure, vacuole, yeast stress.
Publication no. G-2007-0416-467 ©2007 The Institute & Guild of Brewing