Analysis of Flavors and Off-Flavors in Foods and Beverages Using SPME

Importance of the Topic

Solid-phase microextraction provides a rapid, solvent-free sampling technique for isolating flavor and off-flavor compounds in diverse food and beverage matrices, enabling sensitive detection down to low parts-per-trillion levels and supporting quality control, product development, and safety monitoring.

Objectives and Study Overview

This study demonstrates the application of SPME to a range of samples—including alcoholic and non-alcoholic beverages, confectionery, fruits, dairy products, snack foods, peanut butter, coffee, and water—to profile flavor composition, detect off-flavors, and quantify key aroma and odorant compounds.

Methodology and Instrumentation

SPME protocols used a variety of fiber coatings (PDMS, PDMS-DVB, Carboxen-PDMS, CW-DVB, DVB-Carboxen-PDMS) selected based on analyte polarity and volatility. Headspace extractions were conducted at controlled temperatures (30–65°C) for 1–30 minutes, followed by thermal desorption in GC or GC/MS inlets. Separation was performed on capillary columns such as VOCOL, SUPELCOWAX 10, MDN-5, SPB-1 SULFUR, and PTE-5. Detection modes included quadrupole and ion trap mass spectrometry, flame ionization detection, and selected ion monitoring for enhanced sensitivity.

Main Results and Discussion

• White wine analysis revealed sulfur dioxide and a range of esters, alcohols, and acids using Carboxen-PDMS fibers and GC/MS.
• Artificial and natural cherry-flavored candies were differentiated by profiling esters, aldehydes, terpenes, and benzaldehyde derivatives.
• Apple fruit headspace sampling with PDMS-DVB captured C5 to C8 alcohols, esters, lactones, and farnesene compounds.
• Milk exposed to UV light showed formation of hexanal, heptanal, and dimethyldisulfide, illustrating lipid oxidation off-flavors.
• Rancid versus fresh potato chips were distinguished by short-chain aldehydes, acids, and ketones as lipid degradation markers.
• Peppermint cookie bar sampling provided quantitation of menthone isomers and menthol by headspace SPME-FID.
• Peanut butter profiling identified volatile components and quantified multiple pyrazines responsible for characteristic nutty aroma via standard addition.
• Coffee ground analysis compared regular and decaffeinated samples, capturing furan derivatives, pyrazines, phenols, and caffeine under headspace and immersion extraction.
• Water samples spiked with geosmin, methylisoborneol, and trichloroanisole demonstrated detection at 1–10 ppt using extended DVB-Carboxen-PDMS fibers and MS selected ions.

Practical Applications and Benefits

• Solventless, rapid sampling adaptable to liquids and solids.
• Broad dynamic range from low ppt to high ppm in a single analysis.
• Customizable fiber selection for target analyte classes.
• Compatible with standard GC, GC/MS, and FID instrumentation.
• Quantitative accuracy through internal or standard addition methods.

Future Trends and Potential Applications

• Development of advanced fiber chemistries with greater selectivity and sensitivity.
• Integration with high-resolution and tandem mass spectrometry for compound confirmation.
• Automation and on-line coupling for real-time monitoring in production environments.
• Expansion into emerging fields such as biomarker sampling, environmental monitoring, and novel food ingredients.

Conclusion

SPME proves to be a versatile, sensitive, and solvent-free approach for flavor and off-flavor analysis across a wide range of food and beverage matrices. Its flexibility in fiber choice and compatibility with common chromatographic detectors make it an essential tool for analytical, quality assurance, and research laboratories.

Reference

• Shirey R E and Sidisky L M. Supelco Application Note T498350, Sigma-Aldrich, 1998.