Characterization of the Key Aroma Compounds in Raw Licorice (Glycyrrhiza glabra L.) by Means of Molecular Sensory Science

Application of the molecular sensory science concept including aroma extract dilution analysis (AEDA) on the basis of gas chromatography-olfactometry combined with gas chromatography-mass spectrometry elucidated the key odorants of raw licorice (Glycyrrhiza glabra L.). Fifty aroma-active compounds were located via AEDA; 16 thereof were identified in raw licorice for the first time. γ-Nonalactone, 4-hydroxy-2,5-dimethylfuran-3(2H)-one, and 4-hydroxy-3-methoxybenzaldehyde showed the highest flavor dilution (FD) factor of 1024. Forty-three compounds were quantitated by means of stable isotope dilution analysis (SIDA; 6 more compounds were quantitated using labeled standards with structures similar to the respective analytes) and odor activity values (OAVs; ratio of concentration to the respective odor threshold) were calculated revealing OAVs ≥1 for 39 compounds. Thereby, (E,Z)-2,6-nonadienal, 5-isopropyl-2-methylphenol, hexanal, and linalool showed the highest OAVs. On the basis of the obtained results, an aqueous reconstitution model was prepared by mixing these 39 odorants in their naturally occurring concentrations. The recombinate elicited an aroma profile very similar to the profile of raw licorice, proving that all key aroma compounds were correctly identified and quantitated.