High Speed Analysis of α-Acids and β-Acids in Hops by using UHPLC

Importance of the Topic

Alpha-acids (humulones) and beta-acids (lupulones) in hops are the primary determinants of beer bitterness and its sensory balance. Precise quantitation of these acids supports consistent flavor profiles and quality control in the brewing industry.

Study Objectives and Overview

This work demonstrates a high-speed UHPLC method for simultaneous analysis of alpha-acids, beta-acids and iso-alpha-acids in both hops and beer. Results are compared to conventional EBC/ASBC HPLC protocols and UV-Vis IBU measurements to validate accuracy and throughput improvements.

Methodology and Instrumentation

The study comprised two analytical workflows:

• Beer analysis following EBC 9.47 and ASBC Beer-23A: quantitation of iso-alpha-acids, alpha-acids and humulinones in five commercial beers.
• Hop pellet analysis per EBC 7.7 and ASBC Hops-14: profiling of three homologues each of alpha-acids and beta-acids.
• Calibration with International Calibration Extract 4 standards; spike-and-recovery tests for method validation.
• High-speed UHPLC conditions: EDTA-modified mobile phase, elimination of pH meter adjustment, 5 min runtime versus 45 min in standard protocols.

Instrumentation Used

• Shimadzu Nexera XR UHPLC system for rapid separation.
• Shimadzu UV-1900i UV-Vis spectrophotometer for IBU measurements.

Main Results and Discussion

High-speed UHPLC achieved complete separation of target acids within 5 minutes—a 90% reduction in analysis time. Key findings include:

• Spike-and-recovery tests yielded >95% recovery and consistent quantitation across six replicates.
• UV-Vis IBU values were inflated in samples with high beta-acid levels (notably IPA), demonstrating interference from non-isomerized hop acids.
• IPA beer exhibited the highest alpha-acid and humulinone concentrations, correlating with elevated bitterness units.

Benefits and Practical Applications

The proposed UHPLC method delivers:

• Rapid, high-throughput quality control for breweries.
• Enhanced analytical specificity by separating homologous acids.
• Reduced operational complexity by removing pH adjustments.
• Capacity for simultaneous multi-component profiling in hops and beer.

Future Trends and Potential Applications

Anticipated advancements include:

• Coupling UHPLC with mass spectrometry for comprehensive metabolite profiling.
• Automation and inline process monitoring in brewing operations.
• Expansion to analysis of hop polyphenols, terpenes and other flavor compounds.
• Application in research on novel hop varieties and craft beer innovation.

Conclusion

The high-speed UHPLC method using the Nexera XR system offers significant improvements in speed and analytical reliability for hop acid quantitation. By outperforming traditional IBU assays in specificity and throughput, it provides a robust tool for brewing quality assurance and product development.