Thermo Scientific BeerNHop Solution

Significance of Isohumulones in Beer Analysis

Isohumulones (iso-α-acids) account for roughly 80 % of beer’s bitterness, contribute antimicrobial stability, enhance foam quality through tensioactive properties, and shape flavor and mouthfeel. Precise quantitation of individual iso-α-acid isomers supports consistent quality control and product comparability.

Objectives and Study Overview

This application note presents a complete UHPLC-based solution for specific separation and quantitation of the six major cis- and trans-isomers of isohumulones in beer. It contrasts standard direct injection with two on-line SPE approaches (standard and rapid separation) to optimize throughput, resolution, and column lifetime.

Methodology and Used Instrumentation

High-performance liquid chromatography (HPLC/UHPLC) with UV detection is employed for specific determination of iso-α-acids. Key hardware and consumables include:

• Thermo Scientific Dionex UltiMate 3000 system packages (SD for direct injection, SD with on-line SPE, RS with rapid on-line SPE)
• SR-3000 solvent rack, LPG-3400SD or DGP-3600 pumps, SRD-3600 degasser, WPS-3000 autosamplers, TCC-3000 thermostatted column compartments
• VWD-3100 variable wavelength detector with 2.5 µL flow cell
• Thermo Scientific Hypersil GOLD columns (3 µm, 1.9 µm) and C8 SPE trap cartridges
• Chromeleon 7.2 Chromatography Data System with dedicated eWorkflows for sequence setup, data processing, and reporting

Main Results and Discussion

Chromatographic profiles demonstrate clear baseline separation of six isohumulone variants (trans- and cis-cohumulone, n-humulone, adhumulone).

• Direct injection yields acceptable resolution but accelerates column fouling and retention time shifts due to matrix effects.
• Standard on-line SPE delivers automated sample cleanup, improves column longevity, and enhances retention time reproducibility.
• Rapid separation on-line SPE coupled with UHPLC enables highest throughput, superior resolution, and reduced solvent consumption.

Benefits and Practical Applications

This targeted UHPLC method offers:

• Specific quantitation of each iso-α-acid isomer versus nonspecific bitterness units.
• Improved method robustness and reproducibility through automated SPE.
• Enhanced laboratory efficiency and cost savings via reduced manual sample preparation and solvent use.
• Actionable quality control data to optimize foam stability, flavor consistency, and product shelf life.

Future Trends and Possibilities

Advances in UHPLC and on-line SPE technology will drive even higher throughput analyses, real-time monitoring in production, and integration with multivariate data analytics to predict sensory attributes. Miniaturized and ambient-flow systems may further reduce resource consumption and enable decentralized breweries to perform in-house quality testing.

Conclusion

The Thermo Scientific BeerNHop Solution provides a turnkey, UHPLC-based approach for accurate, reproducible measurement of individual isohumulone isomers in beer. Automated sample cleanup and flexible system configurations support both occasional and high-throughput workflows, ensuring reliable product quality and process control.

References

1. Caballero I.; Blanco C. A.; Porras M. Iso-α-Acids, Bitterness and Loss of Beer Quality During Storage. Trends Food Sci. Technol. 2012, 26(1), 21–30.
2. Heidorn M. Fast Determination of Iso-alpha-Acids in Untreated Beer Samples with Specific Separation into cis- and trans-Isomers. J. Am. Soc. Brew. Chem. 2013, 71(3), 109–113.