Comparison of Two Beer Samples by GCxGC-TOFMS Utilizing the COMPARE Feature

Importance of the Topic

Monitoring volatile constituents in beer is critical for ensuring consistent aroma and flavor profiles, as well as detecting storage or processing-induced changes that impact product quality.

Objectives and Study Overview

This study employs the COMPARE feature in ChromaTOF software to evaluate differences in twenty targeted volatile compounds between a cold-stored beer (Reference) and the same beer subjected to elevated temperature (Sample).

Methodology and Instrumentation

• Sample preparation: 10 mL beer aliquots extracted via PDMS stir bars in headspace vials at 25 °C and 900 rpm for 120 min.
• Instrumentation: LECO Pegasus 4D GC×GC-TOFMS with Agilent 6890 GC and dual-jet thermal modulator.
• Chromatographic conditions: primary column GERSTEL-MACH LTM (10 m×0.18 mm ID×0.20 μm df) with 30–230 °C at 4 °C/min; secondary DB-17ms (1 m×0.10 mm ID×0.10 μm df).
• Desorption: GERSTEL Twister Desorption Unit and CIS 4 inlet, splitless mode, 20 °C to 250 °C.
• COMPARE criteria: first-dimension RT deviation ±12 s, second-dimension ±0.2 s, spectral match ≥700, S/N ≥5, concentration tolerance ±10%.

Main Results and Discussion

Of the twenty analytes, one compound matched all criteria, two were not detected in the heat-abused sample, and seventeen exhibited concentration deviations beyond ±10%. Observed changes ranged from a 462% increase to a 99% decrease, illustrating significant impact of temperature stress on flavor-active volatiles.

Benefits and Practical Applications

The COMPARE feature provides a targeted, single-point calibration approach for rapid comparison of complex samples, supporting quality control in brewing and other food and beverage industries. Peak table filtering streamlines data management of selected analytes.

Future Trends and Opportunities

Future developments may include expansion to larger compound libraries, adoption of multi-point calibration, integration with chemometric tools for pattern recognition, and real-time process monitoring in production environments.

Conclusion

The COMPARE functionality in ChromaTOF offers a reliable means to detect and quantify targeted volatile differences between samples, enhancing analytical throughput and quality assurance in flavor analysis.

Used Instrumentation

• LECO Pegasus 4D GC×GC-TOFMS system with dual-jet thermal modulator and Pegasus IV TOFMS detector
• Agilent 6890 gas chromatograph
• GERSTEL Twister SBSE PDMS stir bars, Twister Desorption Unit, and CIS 4 cooled inlet
• GERSTEL-MACH LTM primary column and DB-17ms secondary column