Solid phase extraction using new Polar Magic Chemisorber ® 7. Flavor Components in sake (Japanese rice)

Significance of the Topic

The analysis of flavor compounds in sake is essential for quality control, product standardization and sensory profiling in the brewing industry. Polar constituents such as alcohols, organic acids and phenolic derivatives strongly influence aroma and taste. Developing rapid, solvent-free extraction and detection methods supports efficient monitoring of beverage quality and process optimization.

Objectives and Overview of the Study

This technical note investigates a solid phase extraction approach using a novel Polar Magic Chemisorber® MC-PEG coupled with thermal desorption GC/MS for profiling polar flavor compounds in sake. Key goals include:

• Evaluating the extraction efficiency of the MC-PEG sorbent for polar analytes
• Comparing results with a nonpolar sorbent (MC-S500)
• Demonstrating a streamlined workflow from immersion extraction to GC/MS analysis

Methodology and Instrumentation

Sample preparation consisted of immersing a Polar Magic Chemisorber® MC-PEG (30 µm PEG film, 3.8 mL volume) mounted on an Eco-Stick GD into 5 mL of sake with 1 g NaCl at 25 °C for 30 min with stirring. After extraction, the sorbent was rinsed, dried and placed in a pyrolyzer furnace. Thermal desorption was performed from 100 °C to 230 °C (40 °C/min, 3 min hold) under helium flow. Desorbed volatiles were cryo-trapped using a MicroJet Cryo-Trap at the head of a polyethylene glycol column (Ultra ALLOY-CW, 30 m × 0.25 mm i.d., 0.25 µm df). The GC oven was programmed from 40 °C (3 min) to 250 °C (10 °C/min, 14 min), and detection was carried out with a quadrupole mass spectrometer. A parallel analysis employed the nonpolar Magic Chemisorber® MC-S500 under identical conditions.

Used instrumentation:

• Multi-functional Pyrolyzer®
• Magic Chemisorber® MC-PEG and MC-S500
• Eco-Stick GD sampling holder
• MicroJet Cryo-Trap
• GC column Ultra ALLOY-CW (PEG stationary phase)
• Quadrupole mass detector

Main Results and Discussion

Chromatographic profiles revealed that MC-PEG efficiently extracted a range of polar constituents, including acetaldehyde, ethanol, acetic acid, 2,3-butanediol, phenethyl alcohol and tyrosol. The nonpolar sorbent captured fewer polar species and showed enrichment of hydrophobic esters and fatty acids. Observations indicate:

• Selective enrichment of hydroxylated and acidic flavor compounds with MC-PEG
• Rapid thermal desorption–GC/MS analysis without solvent use
• Clear differentiation of polar versus nonpolar flavor profiles

The immersion method combined with thermal desorption offers a quick, reproducible workflow for profiling volatile and semi-volatile polar analytes in complex liquid matrices.

Benefits and Practical Applications

This approach delivers:

• Solvent-free extraction that reduces sample preparation steps
• High sensitivity for polar flavor compounds relevant to sake quality
• Compatibility with standard GC/MS setups for routine analysis

Potential applications include quality assurance in brewing, authenticity testing and research into fermentation dynamics.

Future Trends and Opportunities

Emerging directions may feature:

• Development of novel sorbent chemistries targeting specific compound classes
• Integration with two-dimensional GC and high-resolution MS for deeper profiling
• Automation and on-line coupling for high-throughput screening
• Miniaturized, field-deployable pyrolyzer units for on-site beverage analysis

Conclusion

The Polar Magic Chemisorber® MC-PEG combined with thermal desorption GC/MS provides a simple, solvent-free technique for efficient extraction and analysis of polar flavor compounds in sake. Comparative evaluation with a nonpolar sorbent underscores its specificity and utility for beverage quality assessment.

References

Frontier Laboratories Ltd. Multi-functional Pyrolyzer® Technical Note MCA-017E