G. M. RUEHLE (1); (1) New Belgium Brewing Co, Fort Collins, CO, U.S.A.
Poster
The chemical disequilibrium that exists in fresh beer results in
numerous chemical transformations during storage that have vast
implications for the flavor of the product. Quantifying and
understanding the nature of these changes has presented a challenge to
brewing chemists for decades. Several new tools are becoming
increasingly available that show promise for gauging age related changes
in beer. Aroma extraction dilution analysis (AEDA), solvent assisted
flavor evaporation (SAFE), and multivariate analysis (MVA) can all
contribute to the analysis of aged beer. AEDA is a technique where
serial dilutions of an aroma extract of a sample are analyzed by gas
chromatography-mass spectroscopy/olfactometry. The compounds that
persist by olfactometry at the highest dilution levels have more impact
on the overall aroma of the sample than those that are only present in
lower dilutions. Performing this analysis on beer at different time
points can supplement instrumental data and focus analysis on compounds
that are more important to perception rather than those that simply have
the most dramatic change. MVA is a statistical analysis technique that
can be used for non-targeted analysis of raw spectroscopic data, thereby
allowing a much more holistic and thorough approach than the
quantification of individual compounds traditionally considered to
participate in the aged flavor of beer. These techniques used
individually and in combination show a great deal of promise to further
knowledge on the nature of the chemical changes to the aroma of beer
during storage. This paper presents the combination of AEDA and MVA to
study how the aroma of a commercial ale changes over time when packaged
with and without yeast. Additional applications of AEDA, MVA, and SAFE
to better understand chemical changes in beer are discussed.
Grant Ruehle received his B.S. degree in chemistry, with honors, from
the University of Denver in 2011. He received several distinctions as
an undergraduate student, including the Goldwater Foundation Scholarship
and the ACS Undergraduate Award in Analytical Chemistry. Grant began
working as an intern at New Belgium Brewing in Fort Collins, CO, shortly
before graduating and was hired as a full-time chemist upon completion
of his degree. Grant received the Institute of Brewing and Distilling
Diploma in Brewing in 2012. While at New Belgium, Grant has focused on
GC-olfactory work, GC method development, UPLC method development, and
process improvement and optimization. Grant has been an ASBC member
since entering the brewing industry and is currently chairing a
Technical Subcommittee. Grant spends his free time trail running and
back country skiing in the mountains of Colorado.
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