Screening of Flavor Volatiles in Exhaled Breath After Tasting Cream Cheese and Fruit Punch Utilizing PDMS Foam Tubes, Thermal Desorption and GC-TOFMS

Importance of the Topic

Understanding retronasal flavor release is essential for linking analytical measurements to sensory perception in food products. Breath analysis after tasting provides real‐time insight into volatile compounds responsible for flavor intensity, consumer satisfaction, and product optimization.

Objectives and Study Overview

This work aimed to simplify existing flavor screening methods by directly trapping volatiles from exhaled breath on PDMS foam tubes, eliminating a separate purge step. Three matrices were tested: unflavored cream cheese, cream cheese with double the flavor load, and a fruit punch. Two tasting protocols with varied exhalation volumes and adapters were compared over two days.

Methodology and Instrumentation

Sample Preparation and Sampling Protocol

• Chewing 3 g of cream cheese for 5 s with nose pinched.
• Exhaling 100–200 mL breath through conditioned PDMS foam tubes for 10 s (Day 1) or 20 s (Day 2), using a flow meter or Luer needle adapter for consistent flow.
• HSSE comparison using a PDMS‐coated Twister stir bar for 6 h at room temperature.

Chromatographic Analysis

• Thermal desorption of PDMS tubes at 250 °C in splitless mode; analytes cold‐trapped at −120 °C.
• GC separation on a 30 m × 0.32 mm DB-5 column, oven ramp from 40 °C to 240 °C.
• Detection with LECO Pegasus IV GC-TOFMS; electron ionization at 70 eV; data acquired at 10 spectra/s over m/z 40–400.

Used Instrumentation

• GERSTEL MPS 2 Robotic Sampler with TDU option
• GERSTEL CIS 4 Cooled Inlet System with LN₂ option
• LECO Pegasus IV GC-TOFMS

Main Results and Discussion

Direct PDMS foam sampling captured major ketones, aldehydes, acids, and lactones without inlet freezing despite moisture. Doubling exhalations increased levels of key ketones (2-heptanone, 2-nonanone) but did not significantly enhance detection of certain delta-lactones. Cooling the PDMS phase to 5 °C did not improve volatile recovery. HSSE provided complementary profiles, identifying additional low-abundance lactones not seen in breath sampling. Advanced deconvolution was critical to resolve coeluting delta-lactones sharing similar mass spectra.

Benefits and Practical Applications

• Eliminates labor‐intensive purge steps for faster analysis.
• PDMS foam tubes offer robust, moisture‐tolerant volatile trapping.
• GC-TOFMS with deconvolution enables detailed identification and quantitation.
• Applicable to food R&D, sensory correlation, quality control, and flavor formulation.

Future Trends and Opportunities

• Integration with real‐time mass spectrometric techniques for dynamic flavor release monitoring.
• Development of novel sorbent coatings to capture polar and thermally labile volatiles.
• Combining analytical data with sensory panel evaluations to build predictive flavor perception models.
• Extending the method to diverse food and beverage matrices and time‐resolved kinetic studies.

Conclusion

Direct trapping of breath volatiles on PDMS foam tubes followed by thermal desorption GC-TOFMS offers a streamlined, effective approach for profiling retronasal flavor compounds. While it reliably detects major volatiles, complementary HSSE analysis remains valuable for uncovering minor constituents such as specific delta-lactones. Overall, this workflow enhances analytical speed and depth, supporting improved understanding of flavor release mechanisms.