Widely targeted metabolomics of 142 hydrophilic compounds in beer using liquid chromatography-single quadrupole mass spectrometer

Significance of the Topic

Metabolomic profiling of foods, particularly beverages like beer, provides objective data on flavor, quality and functional constituents. Hydrophilic metabolites such as amino acids, organic acids and nucleotides influence taste, stability and antioxidant activity. A comprehensive, high-throughput method for their simultaneous quantification supports quality control, product development and authentication in the brewing industry.

Objectives and Study Overview

This study aimed to develop and demonstrate a widely targeted metabolomics approach for 142 hydrophilic compounds in diverse beer samples using a single-quadrupole LC-MS system. Four conventional beers (lager, ale, low-malt purine-reduced, soy-based) and two non-alcoholic variants produced via different processes were profiled. Multivariate analysis was applied to classify samples and correlate metabolite patterns with ingredients and manufacturing methods.

Methodology and Instrumentation

Sample Preparation:

• Beers A–D (alcoholic) and E–F (non-alcoholic) diluted 1:10 in water.
• 2-Morpholinoethanesulfonic acid (1 µmol/L) used as internal standard.

Chromatography and Detection:

• Shimadzu Nexera XR UHPLC system coupled to LCMS-2050 single-quadrupole mass spectrometer.
• Ion-pair-free separation parameters adapted from LC/MS/MS Method Package for Primary Metabolites Ver. 3.
• Detection in SIM mode for 142 target compounds covering amino acids, organic acids, nucleosides, nucleotides and phenolic acids.

Key Results and Discussion

Out of 142 targets, 82 metabolites were detected across samples. Conventional lager and ale beers and one non-alcoholic beer yielded over 70 compounds, while the low-malt purine-free beer showed only 22 detections. Principal component analysis (PCA) separated samples by ingredient profiles, grouping low-malt beer and one non-alcoholic variant closely. Hierarchical cluster analysis (HCA) defined two clusters reflecting differences in wort seasoning versus suppressed fermentation processes. Purine-related metabolites were most abundant in the ale, absent in the low-malt purine-free beer. Functional components (GABA, ferulic, vanillic, sinapic and caffeic acids) were enriched in high-malt beers and one non-alcoholic sample, correlating with antioxidant potential.

Benefits and Practical Applications

• The single-quadrupole approach offers a streamlined, cost-effective alternative to tandem MS for broad metabolite coverage.
• Rapid profiling facilitates routine quality assurance and adulteration detection in breweries.
• Data can guide process optimization for improved flavor consistency and enhanced functional properties.

Future Trends and Potential Applications

Integration with high-resolution MS and data-driven workflows will expand analyte scope and sensitivity. Real-time metabolomic monitoring during fermentation can enable predictive control of flavor development. Adaptation to other fermented beverages and food matrices will broaden the utility of this targeted method in foodomics and regulatory settings.

Conclusion

A robust single-quadrupole LC-MS method was established for simultaneous quantitation of 142 hydrophilic beer metabolites. Successful classification of beer types based on metabolite patterns demonstrates its value for quality control, product differentiation and functional evaluation in the brewing industry.

References

Iwata N., Hattori T., Kuhn E., Horie S., Inohana Y. Widely targeted metabolomics of 142 hydrophilic compounds in beer using liquid chromatography-single quadrupole mass spectrometer. 2022 AOAC Annual Meeting.