Program Book - Master Brewers Association of the Americas

O-32
Influence of harvest date, growing location and sub-variety on
the composition of Golding hop essential oil
RAY MARRIOTT (1)
(1) Botanix Ltd., Paddock Wood, Kent, United Kingdom
Goldings, first developed in the 1700s, consist of a group of
traditional English hop varieties for which the exact origin is
unknown. Over the past century at least six sub-varieties have been
grown which are all marketed as “Goldings”. These are cultivated
both in the Kent and West Midlands growing areas of England,
and these distinct geographically areas have very different climate
patterns. Over the last three years hops from all sub-varieties
and growing areas have been harvested at different dates over a
three-week window to determine the effect of these parameters on
the level and composition of the essential oil, particularly those
components considered to be character impact molecules. It has
been possible through this study to recommend an optimal harvest
date for this variety and to provide supplementary information to
brewers when they select hops each year. A better understanding of
the composition of each variety has also enabled a wider choice of
hops to be made available at a time of limited supply.
Ray Marriott received his first degree in biochemistry at Cambridge
and subsequently completed a Ph.D. degree in terpene chemistry
at the University of Bath. Ray joined Botanix Ltd in 1996, where
he is now R&D director. Ray has spent over 35 years in the food
and flavoring industry in the United Kingdom, mostly in technical
management. He is a biochemist and has been primarily concerned
with the extraction and processing of natural products and the
mechanism and enhancement of enzyme pathways responsible for
the generation of key active compounds, particularly those that
can be derived from U.K. crops. Ray is a member both of the IBD
and ASBC and regularly presents papers on the applications of
hop compounds, covering all aspects of their use from aroma to
antimicrobials. He is also visiting professor of chemistry at University
of York, UK.
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O-33
Examination of the flavor potential of glycosidically bound
flavor compounds from hops
LUK DAENEN (1), Femke Sterckx (1), Daan Saison (1), Freddy
Delvaux (1), Hubert Verachtert (1), Guy Derdelinckx (1)
(1) Centre for Malting and Brewing Science (CMBS), K.U.Leuven,
Leuven, Belgium
At the 2006 ASBC annual meeting, we presented results on the
flavor potential of hop glycosides and the influence of yeast. It
became clear that acid and enzymatic hydrolysis of hop glycosides,
extracted from spent hops after supercritical CO 2 extraction, led
to fruity, floral, herbal and/or spicy flavors. Both Saccharomyces
and Brettanomyces brewing yeasts showed a glycoside hydrolase
activity towards hop glycosides. To gain more insight into the
flavor potential of hop glycosides, a more thorough examination of
released hop aglycones was carried out. Well-known (e.g. linalool,
geraniol) and less typical (e.g. methyl salicylate) hop volatiles were
identified. The compounds dihydroedulan I and II (elderberrylike
aroma) and theaspirane A and B (woody- and campherouslike
aromas) increased after enzymatic hydrolysis, and were
identified for the first time in hops and in beer (dry hopped). These
norisoprenoids are most likely formed by partial acid-catalyzed
cyclization of precursors which occur as glycosidic compounds.
Further, the flavor potential of hop glycosides was evaluated in
wort fermentations in which a hop glycoside extract was added at
different ratios. Release of hop volatiles and the glycoside hydrolase
activity of yeast were followed during the fermentations. The use
of different Saccharomyces cerevisiae strains showed that exo-
1,3-β-glucanase activity led to a moderate increase in certain hop
aglycones, like 1-octen-3-ol and dihydroedulanes. The use of a mixed
culture of Saccharomyces cerevisiae and Brettanomyces custersii led
to a remarkably higher release of hop volatiles and demonstrated
the flavor enhancing properties of the β-glucosidase activity of B.
custersii. Here, formation of both the newly identified hop volatiles
dihydroedulanes and theaspiranes was observed. Sensory analysis
showed that an increased addition of hop glycosides led to a higher
general appreciation. The acquired knowledge can be applied
in methods to utilize the flavor potential of hop glycosides more
efficiently to obtain beverages with an improved and refined flavor or
to create new types of beverages.
Luk Daenen finished his M.S. degree in applied bioscience and
engineering, with an option in chemistry, in July 2003 at the
Katholieke Universiteit Leuven, Belgium. He carried out his M.S.
thesis at the Centre for Malting and Brewing Science on the subject
“Non-oxidative Staling Processes in Beer.” He obtained a grant from
the Institute for the Promotion of Innovation through Science and
Technology in Flanders (IWT) in October 2003. Since then, he has
worked as a Ph.D. research fellow at the Centre for Malting and
Brewing Science. His Ph.D. research focuses on the utilization of the
flavor potential of hops and sour cherry by the glycoside hydrolase
activity of Saccharomyces and Brettanomyces brewing yeasts.