Gudrun J Vogeser, PIKA Weihenstephan GmbH, Bavaria, Germany
ABSTRACT: Microbiological analyses are well established in breweries’ routine control, but mostly are not relevant to make a decision—the results either come out too late or they are too indifferent to be of practical use, in the worst case they are both. Fast detection methods including polymerase chain reaction (PCR) are continuously being devised. With improvements in instrumentation and sample handling for PCR analysis, this method is spreading into laboratories for daily production control. The basic thought behind use of PCR is to gain better and earlier knowledge about microbial process contamination due to the considerably lower detection limits of PCR compared with conventional enrichment methods. Beginners in using PCR in microbiology keep their focus on the gain of time due to the shorter duration of pre-enrichment. This study shows applications of PCR and results from routine brewery analyses comparing traditional enrichment methods with results from PCR. Based on case studies it is demonstrated that not only the detection limit factor is important—especially for troubleshooting the precision and specificity of this method is unbeatable. Some contaminations were only detected due to PCR, remaining invisible with the traditional enrichment methods. A major benefit can be drawn from PCR results if sampling within the process line is rethought and adjusted to the new method; fewer samples taken at other time points in the process line resulted in the most effective output.
Gudrun Vogeser received a diploma in microbiology from Eberhard Karls University in Tuebingen, Germany. Her first job was at the Technical University of Munich, Germany, where she finished her Ph.D. thesis in 1992. She was then employed as a scientist at the Chair of Brewing Technology at TU Munich-Weihenstephan, where she examined the use of molecular biology methods, mainly PCR, to detect and analyze beer spoiling microorganisms. In 2000 she founded PIKA Weihenstephan, Pfaffenhofen, Germany, a company that specializes in brewery and beverage microbiology, where she is working as managing partner. Gudrun is a founding member and since 2009 chair of the European Brewery Convention (EBC) Microbiology Sub-committee and an ASBC member.