Intracellular glycogen and trehalose contents as predictors of yeast viability

The use of intracellular glycogen content to determine the amount of yeast which must be added to start a brewery fermentation, as suggested by Quain and Tubb in 1982, has met with mixed success. We have studied the changes in cell viability, as determined by methylene blue staining, along with the intracellular concentration of trehalose and acid- and alkali-soluble glycogen, under a number of experimental conditions in the laboratory: different temperatures, acidification of the medium, and addition of cycloheximide to the medium. The results indicate that while there can be a zone of correlation between viability and the acid-soluble glycogen or trehalose content of the cells, this relationship is specific to the experimental conditions and the storage carbohydrate content of cells cannot be used to predict cell viability without knowledge of the conditions of yeast storage.