Characterization of the Key Aroma Compounds in Heat-Processed Licorice (Succus Liquiritiae) by Means of Molecular Sensory Science

Application of the sensomics concept elucidated the key odorants of heat-processed licorice (Succus Liquiritiae). Forty-nine aroma-active compounds with flavor dilution (FD) factors between 16 and 2048 were detected; 47 thereof were identified, 23 for the first time in heated licorice. 4-Hydroxy-2,5-dimethylfuran-3(2H)-one revealed the highest FD factor of 2048, followed by 3-hydroxy-4,5-dimethylfuran-2(5H)-one, 4-hydroxy-3-methoxybenzaldehyde, 3-hydroxy-2-methyl-4H-pyran-4-one, and 2-methoxyphenol (all 1024). Forty-two substances were quantitated by stable isotope dilution assays (SIDAs), and odor activity values (OAVs; ratio of concentration to the respective odor threshold) were calculated revealing OAVs ≥ 1 for 29 compounds. Thereby, 3-hydroxy-4,5-dimethylfuran-2(5H)-one, 2,3-butanedione, 2-methoxyphenol, and 1,8-cineole showed the highest OAVs in Succus Liquiritiae. To validate the obtained data, a reconstitution model based on an aqueous sucrose solution (50%) was prepared, containing all 29 odorants with an OAV ≥ 1 in their naturally occurring concentrations. The recombinate elicited an aroma profile matching very well with the profile of the original heat-processed licorice, proving the correct identification and quantitation of all key aroma compounds of Succus Liquiritiae.