Yield and chemical composition of Citrus essential oils as affected by drying pretreatment of peels

Citrus peel essential oils have an impressive range of food and medicinal uses. In the present study we investigated the variation in the yield and chemical composition of the essential oils isolated from fresh, ambient-, and oven-dried peels of three Citrus species namely Citrus reticulata (C. reticulata), Citrus sinensis (C. sinensis) and Citrus paradisii (C. paradisii). The hydro-distilled essential oil content from fresh-, ambient-, and oven-dried peels of C. reticulata, C. sinensis and C. paradisii ranged from 0.30-0.50, 0.24-1.07 and 0.20- 0.40 g/100 g, respectively. The maximum amount of the oil was determined in oven-dried while the minimum in fresh peel samples. Using GC and GC/MS, a total of 16-27, 17-24 and 18-40 chemical constituents were identified in the peel essential oils of C. reticulate, C. sinensis and C. paradisii, respectively. The content of limonene, the most prevalent chemical constituent, detected in these essential oils, ranged from 64.1-71.1% (C. reticulata), 66.8-80.9% (C. sinensis) and 50.8-65.5% (C. paradisii). The yield and content of most of the chemical components including limonene (the principal chemical compound detected) of the tested essential oils varied significantly (p < 0.05) with respect to drying treatments and species employed.