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P 027
A scientific look at the flavour
evolution of specialty beers
P 028
Volatile compounds screening of
14 commercial Alsatian beers by
SBSE-LD-GC-MS
P 029
Addition of fermentable and non
fermentable carbohydrates - impact
on the yeast metabolism, sweetness,
palate fullness and SO 2 -content
in beer
Barbara Jaskula-Goiris 1 , Brecht De
Causmaecker 1 , Tom Mertens 2 , Luc De
Cooman 1 , Freddy Delvaux 2 , Guido Aerts 1
1KAHO St.-Lieven, Laboratory of Enzyme, Fermentation,
and Brewing Technology (EFBT), Department Chemistry/
Biochemistry - LFoRCe, Department M2S, KU Leuven, Gent,
Belgium, 2 KULeuven, Centre for Malting and Brewing Science,
Department M2S, KU Leuven, Heverlee, Belgium
Damien Steyer 1,2
1TWISTAROMA, Colmar, France, 2 INRA Colmar, Colmar, France
Torsten Seewald 1 , Christof Reinhardt 1 ,
Thomas Kunz 1 , Frank-Jürgen Methner 1
1Technische Universität Berlin, Lab of Brewing Science,
Berlin, Germany
DESCRIPTION OF TOPIC:
The flavour of beer alters upon storage. Due
to the complexity of both malt and beer production
as well as the intricate composition
of the beer matrix, a multitude of parameters
may have an effect on the flavour stability of
the finished product. Here we compared flavour
instability of pilsner beers with a wide
variety of specialty beers. An increase in colour,
haze and aldehydes content was observed
independent of the beer style. With regard
to the aldehyde content in the fresh and aged
beers, great variations were observed in the
speciality beers, strongly depending on the
type and quality of the malt used. Pilsner
beers show relatively low aldehyde contents
in both fresh and aged beers when compared
to specialty beers. However, despite of the
low aldehyde contents and somewhat better
bitterness stability, pilsner beers were more
prone to stale flavour perception due to much
lower masking effects of fermentation and
hop derived flavours.
DESCRIPTION OF TOPIC:
Characterization of the volatile profile of commercial
beer is of interest for brewers. It allows
to understand what differentiates their
products from competitor. This can also be
used as a tool for product development where
compounds of interest could be measured
and with appropriate modeling, their concentration
enhanced during the production
phases. Fourteen commercial beers from 3
different breweries (Kronenbourg, Meteor
and Heineken) from Alsace were analyzed in
duplicate by Stir Bar Sorptive Extraction Liquid
Desorption-GC-MS. Statistical analysis of
43 semi-quantified volatile compounds enabled
the separation of the beers into distinct
groups. White beers was the most complex
group with high level of β-damascenone and
linalol, geraniol, citronellol whereas ales contained
high level of ethyl caproate, ethyl phenylacetate
as well as 4-vinylguaicol.
Lagers could be separated in 2 groups
according to the amounts of hop volatile
compounds (linalol, α/β eudesmol, methyl
geranate).
DESCRIPTION OF TOPIC:
Aim of this study was to investigate influences
of fermentable and non-fermentable carbohydrate
addition into brewing process prior
fermentation to get a better insight in the influence
on the yeast metabolism, sweetness,
palate fullness and SO 2 -formation.
Compared to the standard wort, the results
demonstrate a general carbohydrate dependent
increase in SO 2 -formation during
fermentation. The highest increase in SO 2
results from the fermentable sugars glucose
and sucrose followed by the non-fermentable
sugar isomaltulose and polydextrose. In correlation
to the non-fermentable carbohydrate
addition the additional SO 2 -formation mainly
based on the increase in osmotic pressure is
limited by the influences on the methionine
pathway, the acetaldehyde production and the
activation of the sulphate-reductase.
Dependent to the used sugar a sensory panel
detected a reversal point where the sweetness
is coming to the fore and gets much
stronger in comparison to the palate fullness.
Barbara Jaskula-Goiris
Damien Steyer
Torsten Seewald
Barbara Jaskula-Goiris obtained her PhD in
Biotechnology from Wroclaw University of
Technology, Poland. Since 2008 she is working
as scientist at the Laboratory of Enzyme, Fermentation
and Brewing Technology of KAHO
St.-Lieven in Gent, Belgium. The main fields of
the research are beer flavour stability, hop alpha-acids
isomerisation, hop chemistry, and
liquid chromatographic techniques.
-Founder-Director of TWISTAROMA -PhD at
the INRA de Colmar on the influence of yeast
strain on the aromatic profile of wine -Engineer
in biotechnologie at the Ecole Supérieure
de Biotechnologie de Strasbourg (ESBS)
Torsten Seewald started his studies in food
technology at the Technische Universität
Berlin (TU Berlin) in October 2004. Since
July 2009, he worked as a student assistant
at the TU Berlin, Lab of Brewing Science and
completed industrial placements at WILD and
Herbstreith & Fox. After graduating in April
2012, he is employed as a chartered engineer
at the TU Berlin, Lab of Brewing Science. His
research focus lies in analysing reaction mechanisms
of carbohydrates and oxidative processes
in beer.
53 34 TH EBC CONGRESS · LUXEMBOURG 26 – 30 MAY 2013