COMPARISON OF EXTRACTION TECHNIQUES FOR VOLATILES IN A SELECTION OF SPIRITS AND LIQUEURS

Significance of the Topic

Volatile and semi-volatile compounds play a critical role in defining the aroma, flavor and safety of distilled spirits and liqueurs. Trace contaminants or flavor-defining constituents occur at low concentrations, requiring sensitive sampling and concentration techniques. Optimizing extraction methods enhances quality control, product characterization and contamination detection in the beverage industry.

Objectives and Overview

This study compared three automated extraction approaches—Dynamic Headspace (DHS), Stir Bar Sorptive Extraction (SBSE) using PDMS Twister™, and a Multi-Volatile Method (MVM) with sequential traps—to assess their performance in capturing volatiles from a variety of spirits and liqueurs. Key goals included evaluating the number and type of compounds detected, determining method suitability for different volatility and polarity ranges, and recommending best practices for routine analysis.

Methodology and Instrumentation

Sample preparation and extraction procedures were standardized:

• DHS: 20 µL of each sample incubated at 80 °C for 5 min, volatiles trapped on Tenax™ TA (2 L at 100 mL/min).
• SBSE (Twister): 1 mL sample diluted with 4 mL water, extracted with PDMS Twister for 3 h under stirring (1 000 rpm).
• MVM: 50 µL sample processed sequentially over Shincarbon and Tenax sorbents according to the MVM protocol.

All extracts were thermally desorbed in splitless mode and introduced to an Agilent 7890 GC fitted with a DB-Wax capillary column (60 m × 0.25 mm × 0.25 µm) at 1 mL/min. The temperature program began at 35 °C (0.5 min hold), ramped 5 °C/min to 250 °C (1.5 min hold). Detection employed MS/Q-QQQ and FID in ~1:1 split.

Main Results and Discussion

Comparison across eight samples (brandy, dark rum, Jack Daniels, cognac, Tia Maria, Drambuie, Becherovka, gin, vodka) revealed:

• SBSE captured the highest compound count in most samples, particularly mid-to-nonpolar volatiles.
• MVM delivered broad coverage of both highly volatile and semi-volatile analytes, though ethanol peaks dominated some profiles.
• DHS provided the best results for volatile alcohols but showed limited enrichment of low-volatility or highly polar constituents.

SBSE underperformed for polar aroma compounds (e.g., phenylethyl alcohol in brandy), whereas the Shincarbon stage in MVM effectively trapped small, highly volatile species like acetaldehyde. Method selection should align with target analyte properties—DHS for major volatiles, SBSE for nonpolar semi-volatiles, MVM for comprehensive profiling.

Benefits and Practical Applications

This evaluation guides analytical laboratories in choosing the appropriate extraction technique for spirit profiling, quality assurance and contaminant screening. Key advantages include:

• Automated sampling with GERSTEL MPS ensures reproducibility and high throughput.
• Tailored sensitivity: select DHS, SBSE or MVM to match analyte volatility and polarity.
• Enhanced flavor fingerprinting supports product consistency, origin authentication and sensory research.

Future Trends and Applications

Emerging directions may include development of novel sorbent coatings for improved selectivity, integration with high-resolution mass spectrometry for structural elucidation, and on-line real-time monitoring in production lines. Advances in data analytics and machine learning will further refine compound identification, enabling rapid authentication and spoilage detection.

Conclusion

No single extraction approach covers all volatile and semi-volatile analytes in spirits. DHS excels at major volatile compounds, SBSE favors nonpolar semi-volatiles, and MVM achieves the most comprehensive analyte range. Selecting the optimal method depends on the specific analytical objectives and target compound classes.

Reference

Ridgway K. Comparison of Extraction Techniques for Volatiles in a Selection of Spirits and Liqueurs. Anatune Ltd., 2019.