Comparison of the Key Aroma Compounds in Fresh, Raw Ginger ( Roscoe) from China and Roasted Ginger by Application of Aroma Extract Dilution Analysis.

By application of a comparative aroma extract dilution analysis on the volatile fractions isolated by solvent extraction and solvent-assisted flavor evaporation (SAFE) from fresh raw Chinese ginger ( ) and roasted ginger, 21 or 33 odorants, respectively, with flavor dilution (FD) factors in the range of 32-4096 were identified. In raw ginger, the highest FD factors were found for ()-isoeugenol, 1,8-cineol, vanillin, geranial, and linalool. After roasting, in particular, the FD factors of 3-(methylthio)propanal (cooked potato-like), 4-hydroxy-2,5-dimethyl-3(2)-furanone (caramel-like), 3-hydroxy-4,5-dimethyl-2(5)-furanone (seasoning-like), and geraniol were substantially increased. The application of static headspace/olfactometry (SHO) on ground raw ginger revealed a high FD factor for highly volatile acetaldehyde which clearly decreased after roasting. By contrast, the SHO application revealed high FD factors for malty smelling methylpropanal and 3-methylbutanal, which both were exclusively detected in roasted ginger. Thirteen odorants, namely, decanoic acid, ()-2-decenal, ()-4-decenal, ()-4,5-epoxy-()-2-decenal, ()-4,5-epoxy-()-2-undecenal, fenchol, ()-3-hexenal, 3-hydroxy-4,5-dimethyl-2(5)-furanone, 4-hydroxy-2,5-dimethyl-3(2)-furanone, 3-methyl-2-buten-1-thiol, 2-methylpropanal, ()-2-nonenal, and 1-nonen-3-one, were identified in ginger for the first time. Chiral analysis showed a much higher percent by weight portion for the ()-enantiomer in citronellal, citronellol, and linalool, which was not much changed during pan-frying.