URS WELLHOENER (1), Annette Fritsch (1)
(1) Boston Beer Company, Boston, MA
During storage, there are different ways to determine the right
maturation time for a beer. From the analytical perspective, parameters
like diacetyl or acetaldehyde are the main focus. Additionally, beers
are tasted at certain times to evaluate for the presence of typical
“green beer” flavors. This is used to indicate if maturation has been
achieved. For breweries without a GC, sensory is the only tool to
determine if the beer is ready for packaging. However, both evaluating
techniques do not focus primarily on the changes in dry hops aroma and
flavor. Our goal was to identify the best “dry hop maturation time” for a
lager beer. If the amount of time on dry hops is inadequate, there will
be a poor release of valuable hop oils; yet, too long dry hopping times
can result in “cheesy” beers. However, to make this applicable, a
compromise must be considered for the right maturation time between the
typical maturation parameters and the optimal time for dry hopping. This
research evaluated the differences over time of hop impact due to the
changes in a lager beer’s composition throughout fermentation. Hops were
steeped for 28 days, and data was collected at 5-day intervals. A
variety of hop aroma compounds, including myrcene, linalool, and
limonene, and the hop acids were monitored. In addition to analytics,
the product was also evaluated sensorially. The aromatic and bitterness
impact of the liquid was rated by a panel of experts. Data were
collected in replicate, and a principle components analysis was
performed to evaluate how the liquid changed during fermentation.
Additional comparisons of the analytics were completed to assess optimum
extraction times and overall hop impact on the product. A compilation
of chemical and sensory results was used to evaluate the change-rates in
hop impact during lager beer fermentation.
Urs Wellhoener is the corporate manager for yeast and fermentation
for the Boston Beer Company, having joined the company in 2007. His
focuses are yeast management and microbiology. He is a technical
graduate as brewer and maltster (1991–1993) and received a Dipl.-Ing.
degree from the Faculty of Brewing and Food Technology of the Technische
Universität München-Weihenstephan (TUM) in 1999. After graduation in
1999, he was a project manager on a yeast project at Veltins Brewery,
Meschede-Grevenstein (1999–2000). Between 2000 and 2007 Urs was a
scientific assistant and doctorate at the Chair of Brewing Technology II
at the Weihenstephan Center of Food and Life Sciences, TUM. Urs
received his Ph.D. degree for his studies on yeast physiology during
fermentation and propagation. During this time he also worked for
Muellerbraeu, Pfaffenhofen, Germany, as QC manager.
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