here - the 34th European Brewery Convention

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 oilderived
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 socalled
'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.
P37
A simple concept to predict beer aging by use of statistical tools
Annika Lagemann 1 , Betina Kessler 2 , Waltraud Kessler 3 , Georg Stettner 1
1 Bitburger Braugruppe GmbH, Bitburg, Germany, 2 Technische Universität München, Center of Life
Sciences Weihenstephan, Freising, Germany, 3 Reutlingen-University, Faculty of Applied Chemistry,
Reutlingen, Germany
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.
P38
Different influences on generation of aging compounds and the improvement of the oxidative
beer flavour stability using active packing material versus SO2-additon
Constanze Ruff 1 , Thomas Kunz 1 , Frank-Jürgen Methner 1
1 Technische Universität Berlin, Lab of Brewing Science, Berlin, Germany
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 EPRspectroscopy
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.
P39