Analysis of Aroma Compounds in Cheese

Significance of the Topic

Cheese flavor is determined by complex mixtures of volatile compounds. Reliable detection of these aroma compounds, including trace sulfur species, is essential for quality control, product consistency, and flavor optimization in the dairy industry.

Study Objectives and Overview

This application note describes the use of a silica-based monolithic adsorbent (MonoTrap RGC18 TD) and thermal desorption GC-MS (TD-GC/MS) to profile volatile constituents in Parmesan and Blue cheeses. The study focuses on improving sensitivity, simplifying sample preparation, and enabling direct thermal introduction of analytes without re-adsorption.

Methodology

• Sample Preparation: 10 g of cheese sample were placed in 40 mL vials and exposed to MonoTrap RGC18 TD adsorbent for 3 hours under agitation.
• Thermal Desorption: MonoTrap devices were inserted into the OPTIC-4 injector liner for desorption at 200 °C for 5 minutes with helium carrier gas.
• GC-MS Analysis: Desorbed analytes were cryo-trapped at –150 °C, then transferred splitlessly into a 60 m InertCap Pure-WAX capillary column with an oven program of 40 °C (5 min) ramped at 6 °C/min to 250 °C. Mass spectrometer operated in scan mode (m/z 29–600).

Instrumentation Used

• OPTIC-4 multi-purpose thermal desorption injector
• GCMS-QP2010 Ultra gas chromatograph–mass spectrometer
• AOC-5000 Plus autosampler with LINEX liner exchange
• MonoTrap RGC18 TD adsorbent (silica monolith with C18, graphite carbon, and activated carbon functionalities)
• InertCap Pure-WAX capillary column (60 m × 0.25 mm I.D., df = 0.25 µm)

Main Results and Discussion

Chromatographic profiles revealed over 35 volatiles in Parmesan and more than 30 in Blue cheese, including key sulfur compounds such as dimethyl disulfide and dimethyl sulfone. The high surface area and hybrid chemistry of MonoTrap enabled efficient adsorption of both polar and nonpolar analytes. Direct thermal desorption with OPTIC-4 preserved labile species and minimized background signals. Compound identities were confirmed by mass spectral library matching.

Benefits and Practical Applications

• Enhanced capture and detection of trace sulfur compounds that are often lost in conventional TD systems
• Minimal sample preparation with low blank levels due to preconditioned MonoTrap devices
• Direct desorption into the GC-MS system reduces analyte loss and enhances reproducibility
• Suitable for routine quality control, flavor profiling, and authentication in dairy product analysis

Future Trends and Opportunities

Advances in adsorbent materials and miniaturized thermal desorption interfaces will further improve volatile analysis workflows. Integration with high-resolution mass spectrometry and automated data analytics could enable real-time monitoring of cheese ripening and process control. Expansion to other food matrices and aroma-driven research areas presents additional application potential.

Conclusion

The combination of MonoTrap RGC18 TD and TD-GC/MS with OPTIC-4 provides a robust and high-sensitivity platform for comprehensive aroma profiling in cheese. This approach overcomes limitations of traditional methods, particularly for sulfur species, and supports enhanced quality assurance in the dairy industry.

Reference

• Shimadzu Corporation Application Note No. 120: Analysis of Aroma Compounds in Cheese First Edition June 2012