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Evaluation and Development of an alternative Analysis Method for rapid Determination of Yeast Vitality
K. Mller-Auffermann, W. Silva, M. Hutzler, and F. Jacob

Brewer's yeast has a significant impact on the taste and quality of beer. It is thus necessary to obtain reliable and operationally useful information of the organisms' vitality. Methods currently used are oftentimes very tedious and involve high expenditure. This research work investigates whether and to what extent it is possible to determine yeast vitality with less effort, using an automated laboratory device that records progression of gas formation online by measuring pressure build-up. To be able to make optimal use of the equipment, ideal test parameters such as test temperature, cell concentration, fermentation medium, headspace volume and system settings were identified and described in detail. Based on the parameters identified, direct comparisons with other established measurement methods for determining yeast vitality followed, such as the Fermentometer Method according to Hlav?cek and ICP measurement. The method developed here was found to provide reliable, reproducible and comparable results that correlated directly with the other methods. Based on these findings, some industrial-scale tests were carried out in order to fully evaluate the potential of this analysis for process optimization.

Descriptors: Yeast, yeast vitality, CO2 evolution, pressure build-up, fermentative capacity, yeast concentration

BrewingScience - Monatsschrift fr Brauwissenschaft, 67 (May/June 2014), pp. 72-80