Volatile Composition and the Key Aroma Compounds of the Citrus tachibana (Makino) Tanaka Peel Essential Oil

Gas chromatographic analysis of Citrus tachibana (Makino) Tanaka peel essential oil showed that the volatile composition contained 111 components including monoterpenes, sesquiterpenes and oxygenated compounds. Limonene (69.1 %), gamma-teipinene (10.5 %) and beta-pinene (5.07 %) were the major components. Linalool (0.95 %) and linalyl acetate (1.01 %) were the major oxygenated compounds. We first analysed the key aroma compounds by aroma extract dilution analysis. Among 33 compounds with flavour dilution (FD) factors that were >= 4. alpha-pinene (pine, FD = 2048), beta-pinene (pungent. FD = 1024) and linalool (floral. FD = 1024) were the predominant odorants. Vinyl ketones and unsaturated aliphatic aldehydes were also determined, even though they were present at very low concentrations: (Z)-1,5-octadien-3-one (pungent, metallic), 1-nonen-3-one (mushroom. metallic), 7-methyl-1,6-octadien-3-one (mushroom, metallic), (Z)-2-nonenal (tallowy), (E)-2-nonenal (fatty, rice). (Z)-4-decenal (spicy, waxy), (Z)-2-decenal (fatty), (E,Z)-2,4-decadienal (fatty. rice), (E,Z)-2,7-decadienal (cucumber), (E,E,Z)-2,4,7-decatrienal (green, orange), trans-4,5-epoxy-(E)-2-decenal (albedo) and trans-4,5-epoxy(E,Z)-2,7-clecadienal (albedo). These compounds may be important to the Tachibana aroma.