L. F. CASTRO (1), C. F. Ross (1); (1) Washington State University, Pullman, WA, U.S.A.
Poster
A headspace solid-phase dynamic extraction coupled with gas
chromatography-mass spectrometry (HS-SPDE-GC-MS) method for the analysis
of the volatile fraction of beer was optimized. Optimization was
performed using a mixture of five volatile compounds commonly found in
beer (isoamyl acetate, ethyl hexanoate, myrcene, benzaldehyde,
linalool). A two-level full factorial design was used, with extraction
temperature, extraction strokes, and fill/eject speed as the main
factors. The results showed that extraction time and temperature had a
significant effect on the peak area response of the volatile compounds.
To determine the ideal conditions for extraction, a final optimization
of the significant factors was carried out using a Doehlert matrix
design. An extraction temperature of 42°C and 46 extraction strokes
provided the highest total peak area GC response for the five volatile
compounds. This optimized method was applied in the analysis of five
commercial beers. A variety of compounds from different chemical classes
were extracted from each sample, reflecting the difference in volatile
profile among beers brewed with different raw materials, adjuncts, and
brewing conditions, and the application of the SPDE method for volatile
compound determination.
Luis Castro is a post-doctoral research associate at Washington State
University. He received his B.S. degree in chemistry from the
University of Costa Rica in San José. After two years spent working in
both industry and academia, he moved to Washington State University,
School of Food Science, to pursue graduate studies. After obtaining his
M.S. degree in food science under Barbara Rasco, working in the field of
food safety, he enrolled in the Ph.D. program at the same institution,
working with Carolyn Ross. Under her supervision he started research on
beer flavor chemistry and received his Ph.D. degree in December 2013.
His current research combines sensory analysis and analytical chemistry
techniques to determine the impact of flavor and matrix components on
the sensory and chemical properties of beer.
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