BCOJ Symposium: Technology for the Future Session
Takako Inui, Suntory Liquors Limited, Osaka, Japan
ABSTRACT: Aroma characters derived from hops are very important
for the quality of beer, as they can give an attractive sensory impact
to beer by choosing suitable hop varieties, hop boiling conditions,
fermentation conditions, and so on. In order to develop strategies to
facilitate an attractive hop aroma in beer, we have been trying to
clarify the relationship between hop aroma qualities in beer and brewing
conditions. Many researchers have been studying hop aroma focused
mainly on the essential oils in hop such as terpenoids. But these
compounds are not necessary brought directly into beer products as they
are. When they go through thermal reaction, oxidation, revelation from
their glycosides, and biotransformation by yeast, there are chemical
changes to different odor active compounds that are destined for final
beer products. Such complexity makes the profiling of hop aroma in beer
for mining the key compounds very difficult. In order to estimate the
influencing compounds, the idea of "food metabolomics" was introduced
for analyzing the data. Five hopped beers were brewed using different
hop varieties, as well as unhopped beer. The aroma compounds were
analyzed comprehensively by GC×GC/TOF-MS, and sensory evaluation was
also performed. Both results, chemical analysis and sensory data, were
subjected to multivariate analysis to correlate chemical components and
sensory evaluation. As a result, influencing compounds were
distinguished from other numerous compounds. For suitable boiling
conditions to give preferable hop aroma quality and intensity, linalool,
a floral note component in beer, was used as one of the indicators for
the hopped beer, because controlling the concentration of linalool in
beer is essential for achieving target quality. In order to rationalize
the factors that may affect the concentration of linalool during the
boiling process, we have carried out brewing experiments using model
solutions, as well as pilot scale brewing under various conditions, such
as the timing of hop addition, temperature and amounts of late hopping,
gravity of the wort, and so on. We also have focused on other hop aroma
compounds, in addition to linalool, to explain the differences in
organoleptic characteristics of beers. For the fermentation conditions,
two different brewing yeast strains were used to examine the resulting
hop aroma characteristics and hop derived components. Although the same
cold wort was used for the fermentations, significant differences in hop
aroma portraits were perceived. The obtained results, thus, are
attributable to differences in metabolites generated from the components
derived from hops by different yeasts. Further detailed investigations
on the effects of hop on beer aroma, particularly on the changes during
brewing, are awaited.
Takako Inui graduated from Kyusyu
University. She started her research career with Suntory Ltd. in 1989 at
the Institute for Fundamental Research. Since 2002, she has been
conducting research at the Institute for Beer Development on the
development of brewing technology and flavor science of beers, including
hops.
VIEW PRESENTATION S-3
