Characterization of the Major Odor-Active Compounds in the Rhizome of the Greater Galangal (Alpinia galanga)

The rhizomes of Alpinia galanga have a characteristic aroma, the molecular basis of which has not yet been fully clarified. Application of gas chromatography-olfactometry and aroma extract dilution analysis to the volatiles isolated from fresh A. galanga rhizomes by solvent-assisted flavor evaporation led to the detection of 43 odorants with flavor dilution factors of 1-4096. Enantiodifferentiation increased the number to 47. The structures of 36 odorants were elucidated, 18 of which were previously unknown in A. galanga, and 21 were shown to be present in concentrations above the odor threshold concentration (OTC). High odor activity values (OAVs; concentration/OTC) were particularly obtained for 1,8-cineole (130000), (S)-galangal acetate (44000), and myrcene (8000). As proof of success, the characteristic aroma of A. galanga rhizome was reconstructed with 20 major odorants in their natural concentrations. The results will contribute to a deeper molecular understanding of the aroma of Alpinia species and serve as the basis to study aroma changes during processing and culinary use of A. galanga rhizome.