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Quantitative Analysis of Humulene in Beer

Quantitative Analysis of Humulene in Beer. Joseph Frederick CHEM 4101, Fall 2010 December 10, 2010. What is Humulene?. Humulene is an essential oil found in hops used for brewing. Has an “elegant” flavor. Higher levels found in aroma hops. Hypothesis.

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Quantitative Analysis of Humulene in Beer

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  1. Quantitative Analysis of Humulene in Beer Joseph Frederick CHEM 4101, Fall 2010 December 10, 2010

  2. What is Humulene? • Humulene is an essential oil found in hops used for brewing. • Has an “elegant” flavor. • Higher levels found in aroma hops.

  3. Hypothesis • There is a certain concentration of humulene that the majority of people will prefer in beer. Importance of solving hypothesis • If this concentration was to be determined then the beer that would appeal to the largest amount of people could be produced.

  4. Background • Normal levels in Japanese beers (usually have lower levels of essential oils than Western beers): 0.23 – 0.73 ppb • These low levels are suitable for this method implying that it would be acceptable for American and European beers which will have higher concentrations of humulene.

  5. Procedure • Survey needed in order to determine which level of humulene in beer is preferred by the most people. • Stir bar-sorptive extraction using PDMS coated stir bar added to 30 mL beer diluted to 150 mL with distilled water, stir for 2 hours at 40°C • Use Twister desorption unit to get sample to GC/MS

  6. Stir Bar-Sorptive Extraction • Stir Bar-Sorptive Extraction preferable to liquid extraction methods. • No solvent used. • Lower loss of product due to analysis. • Far more efficient extraction of humulene. • Need to use Twister desorption unit to desorb compounds from PDMS.

  7. Method of Choice: GC/MS • Allows for separation and then identification simultaneously • Good limit of detection: 0.035 ppb

  8. Agilent 6890 • Gas Chromatograph • Carrier Gas: Helium • DB-WAX GC Column with polyethylene glycol as the stationary phase (60 m length X 0.25mm i.d,; film thickness = 0.25μm)

  9. MSD5973N • Mass spectrometer • Quadrupole • Electron Impact Mode at 70 eV • Resolution: 0.1 amu • Sensitivity: 1 pg

  10. Other Analytical methods

  11. Conclusion • Humulene levels at a certain level will make beer more appealing to the most people. • Stir bar-sorptive extraction and GC/MS allows for relatively cheap determination of humulene levels. • Since low amounts of beer are required for this method (30 mL) and no solvent is used, constant monitoring of humulene (and other essential oils) may be implemented.

  12. References • 1. Kishimoto, Toru, et al., "Analysis of Hop-Derived Terpenoids in Beer and Evaluation of their Behavior Using the Stir Bar-Sorptive Extraction Method with GC-MS". Journal of Agricultural and Food Chemistry, 2005, 53, 4701-4707. • 2. Fix, George. Principles of Brewing Science. Boulder, Colorado: Brewers Publications, 1989 • 3. Dev, S. “Studies in Sesquiterpenes-XVIII: The Proton Magnetic Resonance Spectra of Some Sesquiterpenes and the Structure of Humulene”. Tetrahedron. 1960, 9, 1-9 • 4. Musenga, A., et al, "analysis of aromatic and terpenic constituents of pepper extracts by capillary electrochromatography". J. Sep. Sci., 2007, 30, 612-619

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