Volatile components of peel cold-pressed oils of two cultivars of sweet orange (Citrus sinensis (L.) Osbeck) from Ethiopia

Cold-pressed fruit peel essential oils of two cultivars of sweet orange (Citrus sinensis (L.) Osbeck), Valencia and Hamlin, from Ethiopia were analyzed by capillary GC and GC–MS, without prior separation, and compared with each other. On two different GC columns, 58 components representing an average of 99.9% of the total volatile fraction were positively identified. Trans-carveol was proved for the first time as one of the components in cold-pressed orange oils. Monoterpene hydrocarbons followed by aldehydes and alcohols were the predominate quantitative composition of the volatile part in both the Valencia and Hamlin oils. Their percentage compositions, respectively, were 98.61% and 99.14% in total monoterpene hydrocarbons, 0.76% and 0.49% in aliphatic and terpenic aldehydes, and 0.47% and 0.18% in total alcohol concentration. In the cold-pressed oil of Valencia, oxygenated volatiles amounted to 1.26%, while in Hamlin amounted to only 0.70%. Compared to the same cultivars recently reported from other countries, high concentration of neral (0.09%) and geranial (0.16%) were found in Valencia orange oil. The major aliphatic aldehydes quantified in both oils are n-octanal and n-decanal, which are especially important character-impact constituents of sweet orange oils. Values for individual components like n-octanal, n-decanal and linalol were above, below or within values reported earlier.