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Flavor/Fragrance Profiles of Instant and Ground Coffees By Short Path Thermal Desorption
by Sandford V. Overton and John J. Manura
INTRODUCTION
The aromas and flavors of coffee are responsible for their aesthetic value and consumer appeal. The flavor/fragrance qualities are greatly dependent on the volatile and semi-volatile organic compounds contained both in the liquid matrix and the headspace aroma (1). Analytical techniques are needed to profile and identify flavors, fragrances, off-flavors, off-odors and potential contaminants that may be present as flavor and fragrance additives, residual solvents from the manufacturing process or as impurities from the raw materials. Results of such analyses may be used for developmental research, as well as production quality control.
Two techniques were utilized to compare flavor profiles of two different brands of instant coffee and one brand of ground coffee. The first technique involved collecting VOC's using a newly designed purge and trap system (P&T) (2), followed by trapping on an adsorbent resin and subsequent analysis by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) using a Scientific Instrument Services (S.I.S.) Model TD-2 Short Path Thermal Desorber accessory. The second technique, Direct Thermal Desorption (DTD) (3) involving the Short Path Thermal Desorption accessory, permits the analysis of coffee samples. These samples were placed directly in glass-lined stainless steel (GLT) desorption tubes; the volatiles and semi-volatiles were thermally extracted into the GC injection port for subsequent analysis.
