G. VOGESER (1); (1) PIKA Weihenstephan, Pfaffenhofen, Germany
Poster
Microbial stability is an integral part of beer quality. Breweries
implement a variety of monitoring processes, but due to the lack of
specificity in microbiological results, it is usually unclear as to what
decisions need to be made. The use of specific enrichment media,
together with PCR identification, provides broader information about the
spoilage potential of a detected microorganism compared with
conventional methods. Properties of specific spoilage organisms have
unique influences on the final product, ranging from different growth
potentials that influence shelf life to the production of off-flavors
that influence taste. To add another level of complexity to this task,
more and more craft breweries are using lactic acid bacteria, normally
regarded as spoilers in traditional brews, for their specialty products.
These brewers not only need to monitor the composition of their lactic
acid bacteria mixtures, but also must avoid contamination of their other
products with these organisms. Using different optimized media for
alcoholic, non-alcoholic, and mixed beverages improves the detection
limits for spoilers and overall product quality. This holds true for the
challenges faced by the production of other modern specialized
products. The complexity of craft brewing is increasing as breweries are
adding fruit concentrates and various other ingredients and flavorings.
The standard microbiology testing procedures that have worked for more
traditional brews are not always sufficient to handle these new
microbial challenges to quality control. Our work consists of
determining the variation in growth rates and time to detection of
relevant spoilage organisms using different beverage-specific nutrient
media and PCR kits. We can see that the choice of enrichment medium
clearly influences the detection rates for beer spoiling bacteria,
including lactic and acetic acid producers, as well as yeasts. Some
spoilers grow faster in an optimal medium, while some may not grow at
all in certain standard media. Even the differentiation between brewer’s
Saccharomyces yeast and wild Saccharomyces strains can be
reliably achieved by optimizing copper containing selective agar media.
Used in conjunction with PCR, brewers can bring an unparalleled level
of quality control to their operations through use of media optimized to
face the challenges of an increasingly complex craft brewing market.
Gudrun Vogeser is a specialist in microbiology and molecular biology
techniques for the detection of beer and beverage spoilage organisms.
She is a founding member of the European Brewery Convention (EBC)
Microbiology Committee and has held the chair since 2009. She completed
her undergraduate work in microbiology and received her Ph.D. degree in
1992 at the Chair of Brewing Technology in Weihenstephan, Germany. Her
post-doctoral work focused on utilizing molecular biology methods for
the fast detection of beer spoilage bacteria, with a focus on polymerase
chain reaction (PCR). In 2000, after working as a scientist at the
Chair of Brewing Technology for several years, she founded PIKA
Weihenstephan, Pfaffenhofen, Germany, of which she remains the owner.
Her company specializes in serving the brewing industry in
microbiological analytics through diagnostics and products.
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