DETERMINATION OF AROMATIC ALCOHOLS IN BEER USING THE SOLID PHASE EXTRACTION (SPE) FOLLOWED BY GAS CHROMATOGRAPHY- MASS SPECTROMETRY (GC- MS). PART II. – THE CONTENT OF AROMATIC ALCOHOLS IN CZECH BEERS

Significance of the Topic

Brewing aroma is strongly influenced by aromatic alcohols, which affect both flavor and consumer perception. Reliable quantification of these compounds supports quality control in brewing, enables optimization of fermentation processes and guides technological adjustments for various beer styles.

Study Objectives and Overview

This work presents Part II of a study applying solid phase extraction (SPE) followed by gas chromatography–mass spectrometry (GC-MS) to quantify aromatic alcohols in Czech beers. It aims to report real concentration ranges in draft, lager and non-alcoholic beers and to explore how production technology influences these sensory-active constituents.

Methodology and Instrumentation

An SPE procedure using LiChrolut EN cartridges was employed to isolate aromatic alcohols from beer samples after pH adjustment. The extracts were analyzed by GC-MS (Trace GC Ultra – DSQ II) under a temperature-programmed column method and selective ion monitoring. An internal standard added at the extraction outset ensured compensation for analyte losses. Key chemicals included guaiacol, 2-phenylethanol, 4-ethyl- and 4-vinyl-guaiacol, eugenol, tyrosol and tryptophol.

Key Results and Discussion

Levels of guaiacol, 4-ethylguaiacol and eugenol proved consistent across draft, lager and non-alcoholic beers. In contrast, 2-phenylethanol, tyrosol, tryptophol and 4-vinylguaiacol were significantly higher in lager beers. Non-alcoholic samples produced by interrupted fermentation displayed markedly lower 2-phenylethanol than conventional beers, whereas vacuum-distilled beers retained comparable levels. Variability among breweries indicates strain selection, fermentation method and dealcoholization critically affect aromatic alcohol profiles. Reported concentration ranges for certain compounds exceeded values previously published, highlighting the method’s sensitivity and broad dynamic range.

Advantages and Practical Applications

• Enhanced sensitivity and selectivity over traditional distillation-based extractions.
• Broad analytical scope covering low- and high-abundance alcohols.
• Robust quality control tool for breweries to monitor process impact on flavor.

Future Trends and Opportunities

Further research may include systematic studies on yeast strain metabolism, fermentation parameters and dealcoholization techniques to tailor aromatic profiles. Integration with sensory panels and multivariate data analysis could advance predictive flavor modeling and support product differentiation.

Conclusion

The SPE–GC-MS method provides a reliable, comprehensive approach for quantifying aromatic alcohols in beer. It reveals clear differences among beer types and production technologies, offering breweries a powerful tool for process optimization and quality assurance.

References

1. Čulík J. et al., Kvasny Prum. 55, 2009, pp.177–187.
2. Čulík J., Figalla K., Horák T., Kellner V., Kvasny Prum. 45, 1999, pp.4–7.
3. Čulík J., Figalla K., Jurková M., Poledníková M., Kvasny Prum. 45, 1999, pp.91–94.
4. Pollock J.R.A., Brewery Science, Vol.2, Academic Press, 1981.
5. Moll M., Beer and Coolers, Lavoisier, Paris, 1991.
6. Krüger E., Anger H.M., Kennzahlen zur Betriebskontrolle, Behr’s Verlag, 1996.
7. Analytica EBC, European Brewery Convention, 5th ed., Fachverlag Hans Carl, 1998.
8. Dufour J-P. et al., J. Am. Soc. Brew. Chem. 60, 2002, pp.88–96.