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P 036
From wort to beer: The evolution
of hoppy aroma of single hopped
beers produced by early kettle
hopping, late kettle hopping and dry
hopping
P 037
A simple concept to predict beer
aging by use of statistical tools
P 038
Different influences on generation
of aging compounds and the improvement
of the oxidative beer flavour
stability using active packing material
versus SO 2 -additon
Michael Dresel 1 , Tatiana Praet 1 , Filip
Van Opstaele 1 , Ann Van Holle 2 , Jan Van
Nieuwenhove 2 , Dirk Naudts 2 , Denis De
Keukeleire 3 , Guido Aerts 1 , Luc De Cooman 1
1KAHO Sint-Lieven University College, KU Leuven Association,
Laboratory of Enzyme, Fermentation and Brewing
Technology, Ghent, Belgium, 2 De ‚proef‘brouwerij, R&D
Department, Lochristi, Belgium, 3 Em. Prof., Ghent University,
Ghent, Belgium
Annika Lagemann 1 , Betina Kessler 2 ,
Waltraud Kessler 3 , Georg Stettner 1
1Bitburger Braugruppe GmbH, Bitburg, Germany, 2 Technische
Universität München, Center of Life Sciences Weihenstephan,
Freising, Germany, 3 Reutlingen-University, Faculty of Applied
Chemistry, Reutlingen, Germany
Constanze Ruff 1 , Thomas Kunz 1 ,
Frank-Jürgen Methner 1
1Technische Universität Berlin, Lab of Brewing Science,
Berlin, Germany
DESCRIPTION OF TOPIC:
Knowledge of the impact of early kettle, late
kettle and dry hopping on the final flavour
sensation of beers is rather fragmentary. To
gain insights into the way hoppy aroma develops,
samples were taken at different stages
along the brewing process of single-hopped
beers and analysed, thereby focussing on accurate
determination of the full spectrum of
hop oil-derived components. This study pinpoints
analytical and sensory changes induced
by the boiling and fermentation process,
lagering, beer clarification and pasteurisation.
Our data shows both qualitative and quantitative
changes of hop oil-derived volatiles at
the former mentioned production stages and
reveals that individual analytes greatly differ
in their behaviour, e.g. clarification caused a
crucial decrease of volatiles associated with
the so-called ‚noble/spicy‘ aroma. Furthermore,
the choice of the hop variety used for
dry hopping, contributes significantly to the
overall perceivable aroma by boosting individual
volatiles.
DESCRIPTION OF TOPIC:
There are numerous volatile flavoring substances
whose influence on the flavor of
aged beer is widely discussed in literature.
For practical reasons, the complete analysis
of all of those compounds could not be incorporated
into everyday laboratory routines. For
this reason, we made a selection of 37 volatile
compounds which were measured in fresh
Pils and beer that had been stored for six
months via GC-MS/MS. Measurements were
carried out monthly over a time course of two
years. By use of the principal component analysis
on this dataset, we were able to identify
nine key substances which allow a classification
as either fresh or stored beer, with an
accuracy of 90%. The validity of this data was
confirmed by sensory recombination experiments.
Due to its reliability and the largely automated
instrumental detection, this simple
tool marks a noticeable facilitation regarding
prediction capabilities of beer aging, which
otherwise would only be possible by means
of human sensory analysis.
DESCRIPTION OF TOPIC:
Beer off flavour caused by oxidation has
been attributed to the formation of specific
aging compounds. The mechanisms may
differ but they all involve activated oxygen
species, highlighting the importance to avoid
oxygen entry during the brewing process
and storage. The technique combination of
EPR-spectroscopy and the ascertain of specific
aging compounds as oxygen indicator via
GC-MS is predestined to get a deeper inside in
influences of SO 2 -additon in comparison and
in combination to different crown liners with
O 2 -scavenger properties on the oxidative beer
stability. As expected beer with SO 2 -additon
and different O 2 -scavenger exhibited higher
flavour stability. A remarkable and for the
mechanism important point is that a comparable
increase in oxidative stability with SO 2 -
additon or O 2 -scavenger leads to a different
positive effect on the formation of aging compounds
during storage. The results offer a
useful knowledge about the right proceeding
to increase oxidative beer stability.
Michael Dresel
Annika Lagemann
Constanze Ruff
Michael Dresel studied Food Chemistry (2003-
2007) and became „State Certified Food Chemist“
after 1 year at the bavarian state (2008).
2009-2012, he worked on his PhD thesis on
hops hard resin (T. Hofmann, TU Munich) and
completed a 2 month exchange program
under the supervision of J.F. Stevens (Linus
Pauling Institute, Oregon State University) in
2012. Since Nov. 2012 he works in Belgium as
a Post-Doc at KAHO Sint-Lieven. His research
focuses on sensory-active compounds of
hops and beer.
Laboratory manager, Bitburger Braugruppe
GmbH, Bitburg, Germany (July 2011 to present)
Flavour scientist, Bitburger Braugruppe
GmbH, Bitburg, Germany (September 2008 to
June 2011) Scientific assistant, Chair of Food
Chemistry and Molecular Sensory Science,
TUM, Freising, Germany (Oktober 2007 to July
2008) Scientific assistant, Institute of Food
Chemistry, WWU, Münster, Germany (May
2005 to September 2007) Study of Food Chemistry,
University of Bonn and CVUA Münster
(1998-2005)
Constanze Ruff has started her scientific career
with having a chemistry summer school
at the FU Berlin. After finishing school she joined
an internship at Herbstreith & Fox Company.
She started studying chemistry at the
Freie Universität Berlin. In March 2011 she
switched to the TU Berlin to the compartement
of Food Chemistry. At the moment she
is working at her pre-Diploma. Her research
work began in Nov. 2010 as a student research
assistant at the TU Berlin Lab of Brewing
Science.
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