Analysis of Selected Hop Aroma Compounds in Commercial Lager and Craft Beers Using HS-SPME-GC-MS/MS

Abstract

In recent years, hop aroma emerged as a key quality characteristic of popular beer styles. Accordingly, the instrumental analysis of hop derived odorants in beer advanced as a must have analytical technique for research and quality control purposes. Still, the analysis of hop aroma compounds is challenging. Substance concentrations might strongly vary depending on the beer style, matrix effects might hinder reliable quantification, and SPME-GC-MS based protocols are suspected to lack (long-term) stability. The current paper describes the validation and application of a headspace solid-phase microextraction (HS-SPME) – gas chromatography (GC) – tandem mass spectrometry (MS/MS) method for analysis of 16 selected hop aroma compounds in beer. To enable rapid and reliable quantification of selected terpenes, terpenoids, and esters across a wide working range (1–1000 µg/L), instrumental parameters were optimized and three stable isotope labeled standards, namely d₅-linalool, d₂-myrcene, and d₆-citronellol were synthesized and characterized by nuclear magnetic resonance (NMR) spectroscopy. Extensive method validation and routine application proves the excellent selectivity, sensitivity, and robustness of the method in all relevant matrices such as light hopped lagers and dry-hopped ales.

Keywords:

• Beer flavor
• hop aroma
• HS-SPME-GC-MS/MS
• tandem mass spectrometry
• terpenes

Acknowledgments

The authors wish to thank Sven Hanelt for developing the strategy for d₆-citronellol synthesis and Juri Rappsibler (Technische Universität Berlin) for providing access to the NMR instruments. The skilled assistance of Laura Knoke, Christian Schubert, and Christopher Bergtholdt is gratefully acknowledged.

Declaration of interest statement

The authors declare no conflict of interest.

Additional information

Funding

The SPME-GC-MS/MS instrument used in this study was funded by the German Federal Ministry for Economic Affairs and Energy (Grant No. 49IZ180038).