Chemical profiles of volatiles in four Alpinia species from Kerala, South India

Chemical profiles of volatile oils from four Alpinia species, Alpinia calcarata, A. gaanga, A. malaccensis and A. smithiae, were analyzed by gas chromatography–flame ionization detection (GC–FID), gas chromatography–mass spectrometry (GC–MS) and external standardization. Thirty-seven to forty-eight components (96.8–100%) were identified in the rhizome oils of these four Alpinia spp. Major constituents in A. calcarata were 1,8-cineole (35.9%), β-fenchyl acetate (12.9%), β-pinene (9.1%), camphene (5.6%) and α-terpineol (5.3%). A. malaccensis showed a very different chemical profile with α-phellandrene (36.4%) as its major constituent, followed by β-pinene (4.5%), p-cymene (14.9%), 13,14,15,16-tetranor-8(17)-labden-12-al (4.3%) and (E)-labda-8(17),12-diene-15,16-dial (5.0%). The highest content of diterpenes (10.2%) was found in A. malaccensis. Major constituents in A. smithiae were α-terpineol (15.1%), α-fenchyl acetate (12.5%), β-caryophyllene (9.8%), γ-cadinene (5.5%), (E)-nerolidol (10.1%), caryophyllene oxide (10.1%) and (E)-isoamyl cinnamate (7.2%). 1,8-Cineole content in A. smithiae was only 2.1%. Monoterpene hydrocarbons were absent in A. smithiae. A. galanga was found to be rich in 1,8-cineole (52.9%). Potential molecules such as chavibetol acetate (5.6%), 2-(1E)-propenyl phenol (chavicol isomer, 4.7%) and phenol,4-(2-propenyl)-acetate (chavicol acetate, 1.1%) were detected in A. galanga rhizome oil, justifying its use as a food flavor additive. Potent pungent principle dihydrogalangal acetate (2.2%) was first detected in A. galanga rhizome oil.