Modification of yield and composition of essential oils by distillation time

Altering the distillation times of economically important essential oils such as peppermint (Mentha x piperita L), lemongrass (Cymbopogon flexuosus Steud.), and palmarosa (Cymbopogon martini( Roxb.) oils may allow producers to increase the production, engineer the composition, and decrease the energy required for distillation. Experiments were conducted to model essential oil yield and oil composition of peppermint, lemongrass, and palmarosa oils as a function of the length of the steam distillation time (DT). Maximum essential oil yields of peppermint, lemongrass, and palmarosa were achieved at a DT of 20 min: further increases in DT did not increase oil yields. In lemongrass and palmarosa experiments. DTs of 240 min led to 25-40% reductions in oil yield compared to yields at 20-160 min. This study demonstrated that DT can be used as a tool for obtaining essential oils with specific targeted composition from peppermint, lemongrass, and palmarosa. Secondly, the study found that the optimum length of the DT for maximum essential oil yields of peppermint, lemongrass, and palmarosa was much shorter than the time usually used by researchers and processors. Shorter DT may save producers and processors energy costs and other resources. This study also suggests that comparison of data on oil composition must take into consideration the length of the DT. (C) 2012 Elsevier B.V. All rights reserved.