banner 26. Development of a GC method for the analysis of twelve key fermentation derived volatiles utilizing deuterated internal standards, SPME, and SIM

D. SEDIN (1); (1) New Belgium Brewing Company, Fort Collins, CO, U.S.A.

Technical Session 8 - Methods of Analysis
Tuesday, June 16
1:30–3:15 p.m.
Fiesta 3,4,6,8

The analysis of fermentation-derived volatiles can be critical for ensuring beer flavor consistency, evaluating shelf life, and troubleshooting critical off-flavors in beer. A number of methods have been developed using gas chromatography (GC) with different detectors (for example mass spectrometers [MS] or flame ionization detectors [FID]). In addition, there are a number of sample preparation techniques and different techniques for introducing the sample to the GC, including headspace injection, liquid injection, solid phase micro-extraction (SPME), and stir bar sorptive extraction (SBSE). Choosing the analytes most critical to a brewery’s specific beer styles, then choosing the optimal method to conduct the analysis can be a difficult task. This talk will review the process New Belgium Brewing Company followed to develop, optimize, and validate a method for measuring fermentation volatiles. The first step was to narrow the options; this was accomplished through identifying the primary requirements for the method: high sample throughput, minimal sample preparation, compatible with instrumentation available in our laboratory, measurement of all analytes of significance for our primary brands, linear ranges to bracket all of our different brands, and a limit of quantitation (LOQ) below the flavor threshold for the key analytes. To select the analytes most critical to our beers, we utilized sensory panel data and GC-olfactometry analysis. Flavor thresholds were identified utilizing the ASBC Flavor Database. We compared different sample introduction options/parameters, sample preparation details, columns, and MS parameters. The final, optimized method utilizes deuterated internal standards, 3-phase SPME, and selected ion monitoring (SIM). The method measures 12 analytes (acetaldehyde, isoamyl acetate, isoamyl alcohol, ethyl acetate, phenethyl acetate, ethyl hexanoate, ethyl butyrate, 4-vinyl guaiacol, ethyl octanoate, decanal, 3-methyl butanal, and 2-methyl butanal). The limit of quantitation is below the flavor threshold for all analytes, and the linear dynamic range covers the concentrations found in all of our year-round beers. A full validation was completed for the method. The data are utilized to ensure process consistency, troubleshoot fermentation issues, and will be utilized for flavor matching our beers at a new brewery.

Dana Sedin is the manager of the Analytical Laboratory at New Belgium Brewing Company. He began his career in the brewing industry at Coors Brewing Company, where he held both scientific and laboratory manager positions for 10 years. He is an active member of the American Society of Brewing Chemists (ASBC) and from 2008 to 2012 held the Technical Committee chair position on the ASBC Board of Directors. Dana has a B.S. degree in chemistry from California State University, Sacramento, and a Ph.D. degree in analytical chemistry from the University of Colorado, Boulder. In 2011, Dana completed his Post Graduate Certificate in Brewing from the University of Nottingham. Outside of work, Dana’s time is spent with his wife, Sarah, and daughter, Elena.

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