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​​​​​​​Stresses Imposed on Yeast During Brewing Fermentations and Their Effect on Cellular Activity​​​​

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​MBAA TQ https://doi.org/10.1094/TQ-57-1-0131-01​  | VIEW ARTICLE

 

Graham G. Stewart. International Centre for Brewing and Distilling, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, Scotland (Retired) ​

 

Abstract
Brewer's yeast strains are exposed to a spectrum of threats and "insults" that cultures encounter during wort fermentation. Culture storage (including acid washing) and their propagation can also stress yeast systems. Stresses are a plethora of parameters that a yeast culture tolerates during its propagation, storage, and throughout and between wort fermentations. Stress can result in a number of effects on a yeast culture. These include decreases in yeast viability and vitality, depletion of intracellular glycogen, increases in trehalose, and excretion of intraellular proteinase A and other proteinases, with effects on beer foam stability. Shear of cell wall components will also occur. In addition, modification of a culture's flocculation characteristics can result, together with the formation of unfilterable mannanprotein beer hazes. Finally, increases in respiratory deficient (petite) and other yeast mutants have been reported.  

Keywords: acid washing, brewer's yeast, centrifuges, glycogen, propagation, storage, stress, trehalose​


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