Detection of Aroma Compounds in Food by Gas Chromatography-Mass Spectrometry/Olfactometry

The analytical detection of aroma constituents in food samples presents a challenge. Combining instrumental methods with the human sense of smell represents a state-of-the-art approach for elucidating single aroma-active compounds that contribute to the overall odor of a sample. The complementary use of human olfaction is a necessity since its sensitivity in perceiving odors is in many cases far superior to the detection limits of current instrumental systems. The characterization of odor-active compounds in a sample proceeds via an extraction and subsequent analysis. The volatile compounds, both odor-active and odorless, are typically extracted from a sample using solvent extraction followed by distillation (solvent-assisted flavor evaporation, SAFE). The resulting distillate is then analyzed by gas chromatography combined with olfactometry and mass spectrometry (GC-O and GC-MS/O). Using this tool, aroma-active compounds are detected based on their retention time (or index) and the odor impression perceived by the assessor as they individually elute from the column during chromatographic separation. Structural identification of aroma compounds at a molecular level can be elucidated via their simultaneous analysis by mass spectrometry. This protocol offers step-by-step guidelines for sample preparation and extraction, and subsequent analysis by GC-O and/or GC-MS/O.