Rapid assessment of yeast viability and yeast vitality during alcoholic fermentation

A flow cytometric method based on the measurement of the efflux percentage of carboxyfluorescein after staining of yeast cells with carboxyfluorescein diacetate is reported. This efflux percentage was followed throughout alcoholic fermentations Performed with various pH and temperature conditions. The results obtained show that the efflux percentage is a good indicator of the energetic state of yeast cells and varies through the fermentation in a similar manner to the specific ethanol production rate. These results suggest that this flow cytometric method can be applied to assess viability and to predict vitality of yeast cells in alcoholic fermentations.