Program Book - Master Brewers Association of the Americas

P-218
Detection of yeast in brewery rinse water
CHRIS POWELL (1), Felix Schnarwiler (1), Melanie Miller (2), Fred
Strachan (2)
(1) Lallemand, Montreal, QC, Canada; (2) Sierra Nevada Brewing
Co., Chico, CA
Typically, vessels utilized within the brewing industry are
sterilized or sanitized after use to prevent contamination from
unwanted particulate matter, chemicals or microbes. The type
and composition of cleaning agents can vary significantly between
breweries but typically include hot caustic soda, steam, chlorine
based sanitizers or acid agents such as peracetic acid. While the
efficiency of such cleaning agents is typically good, it is common
practice to perform tests to ensure that vessels are microbiologically
clean. Analysis of water used to rinse vessels after sanitation can be
performed to indicate whether any microbial contamination remains
in the vessel and to ensure that hygiene standards are met. Although
traditional methods based on cultivation are still employed in many
breweries, these techniques are typically slow and only provide a
result after a delay of several days or weeks. Recently there has been
a growing trend toward the implementation of quick and reliable
PCR-based methods for the detection/identification of bacteria
or wild yeast contaminants in beer or process samples. However,
in many instances pre-enrichment for 16–72 h is required prior to
analysis and the level of differentiation provided is excessive for
basic hygiene assessment. Here we describe a simple Q-PCR based
method for the detection of yeast in rinse water samples as a means
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of assessing vessel hygiene. The method described includes the
use of PCR primers designed to detect and identify Saccharomyces
cerevisiae yeast. In addition, we demonstrate the application of a
novel hollow fiber filtration module (Elutrasep) which allows the
accurate recovery of cells from a large sample volume. As such,
pre-enrichment of process samples is not necessary, leading to
a significantly faster response time. Here we demonstrate that
the PCR protocol described may be used to routinely detect yeast
present in rinse water samples. Consequently, a rapid assessment of
microbial loading can be performed, aiding the implementation of
effective HACCP monitoring and allowing proactive decisions to be
made regarding vessel hygiene.
Chris Powell obtained a B.S. degree in biology and environmental
biology in 1996. Subsequently, he occupied a variety of research
positions investigating aspects of heavy-metal toxicity in fission yeast
and oxidative stress in brewing yeast strains. In 1997 Chris moved
to Bass Brewers (now Coors Brewers) to work as part of the research
and development team. Chris began his Ph.D. studies later in the
same year at Oxford Brookes University, in conjunction with Bass
Brewers, and received his doctorate in 2001 on the subject of yeast
cellular aging and fermentation performance. Subsequently, Chris
became involved in a project funded by the European Commission,
exploring mechanisms for the rapid detection of microbial
contaminants within breweries. Chris joined Lallemand in 2004
and is currently in charge of genetic R&D for the identification and
characterization of microorganisms utilized within the food and
beverage industries, in addition to research focused on brewing yeast.