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

The rhizomes of <i>Alpinia galanga</i> 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 <i>A. galanga</i> 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 <i>A. galanga,</i> 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), (<i>S</i>)-galangal acetate (44000), and myrcene (8000). As proof of success, the characteristic aroma of <i>A. galanga</i> rhizome was reconstructed with 20 major odorants in their natural concentrations. The results will contribute to a deeper molecular understanding of the aroma of <i>Alpinia</i> species and serve as the basis to study aroma changes during processing and culinary use of <i>A. galanga</i> rhizome.