L. L. Chan (1), A. Wilson (2), K. MCCULLEY (1), B. Belete-Gilbert (1);
(1) Nexcelom Bioscience, Lawrence, MA, U.S.A.; (2) Brew Hub, Lakeland, FL, U.S.A.
In the early fermentation stages, many types of yeast cells may form clusters that can increase the difficulty for both manual counting, as well as automated image-based cell counting. In this work, we demonstrate a simple and cost-effect method for declumping yeast cells in order to facilitate accurate automated cell counting and viability measurement. We examined the Super San Diego Yeast that has high clumping characteristic during fermentation. A beer sample with Super Yeast was collected from the fermentation tank and treated with a small dose of HCl for 10–30 seconds. A control sample was treated with the same dose of H2O for the same duration. Concentrations of both samples were then measured in an Cellometer X2 image cytometer. Results showed that after declumping treatment, the yeast concentration increased due to the single cell suspension that can be accurately counted. The declumping method also improved the accuracy of measuring viability with PI using Cellometer X2. By utilizing the declumping method, clumpy yeast or yeast in early stage of fermentation can be made into a single cell suspension, which can improve the accuracy in cell counting and viability.
As a field applications specialist for Nexcelom Bioscience, Kelsey McCulley has had the pleasure of working with breweries of all sizes from Louisiana to Utah. Nexcelom's Cellometer image cytometry equipment provides a fast, simple, and accurate means to assess yeast viability and vitality for pitching and throughout the fermentation process. She is a member of the Master Brewers Association of the Americas. Kelsey received her B.S. degree in biomedical engineering from the Georgia Institute of Technology and her Ph.D. degree in bioengineering from Rice University in Houston, where she developed a taste for good Texas beer.