Variations in yield and composition of leaf essential oil from Syzygium aromaticum at various phases of development

The changes in the essential oil yield and composition from Syzygium aromaticum leaf harvested at different phases of development from young leaves to mature leaves were studied. Separation of the essential oils was conducted by steam distillation in a Clevenger apparatus for about 4h. Essential oils analyses were performed by GC/MS. The yield of essential oil (ml per 100 g of DM) of the leaf following the four phases of development was in order of: young leaves (5.1%) > expanded leaves 1 (4.5%) > expanded leaves 2 (4.1%) > mature leaves (3.8%). Sixteen compounds were detected by GC/MS. Eugenol and eugenyl acetate were the dominant components. Eugenol and eugenyl acetate amount had a divergent evolution during the four expansions of leaves. When eugenol reached its highest percentages at expanded leaves 2 (84.00 - 90.48%) and mature leaves stage (88.32 - 90.22%), eugenyl acetate reached the lowest ones with, respectively, 0.96 - 7.16% and 0.36 - 1.64%, but when the eugenyl acetate reached a maximum percentage at young leaves stage with 61.44 - 65.52%, eugenol reached a minimum of 25.43 - 30.38%. It is judicious to collect and extract S. aromaticum leaf in expended leaves 2 (pale green leaves) and mature leaves stage (dark green leaves) in order to obtain the optimal yield and maximum percentage of eugenol.