Title: Comprehensive Characterisation of the hop-derived Sesquiterpenoid Fingerprint of American Kettle hopped Lager Beers
Authors: Praet, Tatiana ×
Van Opstaele, Filip
Baert, Jeroen
Aerts, Guido
De Cooman, Luc #
Issue Date: Nov-2014
Publisher: Fachverlag Hans Carl
Series Title: BrewingScience vol:67 issue:November/December pages:183-194
Abstract: In common brewing practice the typical so-called kettle hoppy aroma of lager beer results from the addition
of aroma hop varieties to the boiling kettle. Years of extensive research has elucidated that hop-derived volatile
flavour-active oxygenated compounds are most likely to impart this kettle hoppy aroma. In particular the
oxygenated sesquiterpenoids are considered to play a key role in the spicy and herbal impression of ‘kettle
hoppy’ aroma of traditional kettle hopped lager beers. However, accurate analytical detection and identification
of these compounds in lager beers is everything but straightforward since these compounds are mostly present
at the low ppb level. Therefore, in this study, three American kettle hopped lager beers expressing clear
hoppy aroma characteristics were analysed via HS-SPME-GC-MS to obtain hop-derived volatile profiles. A relatively
simple methodology using Solid Phase Extraction (SPE) was developed to enrich the hop oil volatiles,
in particular the oxygenated sesquiterpenoids, present in beer and to distribute them over different fractions
to overcome the analytical problem of co-elution. After analysis of these fractions, a remarkable number of
63 compounds was detected in the chromatographic region of interest. Amongst the 41 tentatively identified
compounds, 33 proved to be oxygenated sesquiterpenoids. We also report for the first time the presence of
iso-korajol and 3 caryophyllene derivatives, i. e. 4S-dihydrocaryophyllene-5-one, 6(5→4)-abeo-8,12-cyclocaryophyllan-
5-al and 6(5→4)-abeo-caryophyll-8(13)-en-5-al in lager beer. In addition, olfactory assessment via
GC-O sniffing analyses was performed on the SPE-derived fractions of a lager beer, exclusively hopped with
noble aroma hop varieties. Flavour-active zones were frequently allocated to α-humulene and β-caryophyllene
derived epoxides and alcohols, sustaining the general view that these compounds might indeed play a key
role in kettle hoppy aroma.
ISSN: 1866-5195
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Bioengineering Technology TC, Technology Campuses Ghent and Aalst
Technologiecluster Bioengineering Technologie
× corresponding author
# (joint) last author

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