​Incidence of Saccharomyces cerevisiae var. diastaticus in the Beverage Industry: Cases of Contamination, 2008–2017

MBAA TQ http://dx.doi.org/10.1094/TQ-54-4-1130-01 | VIEW ARTICLE
Tim Meier-Dörnberg, Fritz Jacob, Maximilian Michel, and Mathias Hutzler. Technical University of Munich, Research Center Weihenstephan for Brewing and Food Quality, Freising, Germany.
Saccharomyces cerevisiae var. diastaticus is an obligatory spoilage microorganism in the beverage industry with high spoilage potential owing to its glucoamylase activity. S. cerevisiae var. diastaticus yeast strains can lead to an increase of the carbon dioxide concentration in beverages, with gushing and bottle bursting, caused by their superattenuating ability, as possible consequences. Therefore, the determination of beverage contamination by S. cerevisiae var. diastaticus is of significant interest. This article gives an overview of the incidence of S. cerevisiae var. diastaticus contamination in Europe over the last 9.5 years (2008–2017). The paper is based on analytical data of about 126 S. cerevisiae var. diastaticus instances in 52 companies (anonymous) in Europe recorded by the Research Center Weihenstephan for Brewing and Food Quality of the Technical University of Munich, presented according to their origin (beer, beer-mixed beverages, nonalcoholic beverages, etc.), country, year, and type of contamination. The accredited microbiological laboratory of the Research Center Weihenstephan investigates approximately 15,000 microbiological samples of the beverage industry worldwide per year. Real-time polymerase chain reaction analysis for S. cerevisiae var. diastaticus was conducted and evaluated. About six positive contaminations were detected every year, and 71% of them were caused by contamination events during the filling process of beverages. An increase in contamination incidents and confirmed positive findings can be observed over the last two years. Most problems with S. cerevisiae var. diastaticus contaminations occurred during the third quarter of the year. This analytical evaluation clearly shows the increase in contamination with S. cerevisiae var. diastaticus and the importance of detection in the breweries and the beverage industry in general.

Keywords: Saccharomyces cerevisiae var. diastaticus, Brewing yeasts, Spoilage yeast, Yeast characterization, Superattenuating