The steam and water distillation of leaves of Eucalyptus citriodora was modeled using a complete 2n factorial plan. Eight experiments were carried out, with three easily interpretable variables, for steam distillation and for a first degree polynomial model. The average essential oil yield was 2.3%. Positive effects decreased in the order: duration of the extraction, heating power and state of division of the plant. Interactions were negligible. Extraction conditions had no practical impact on citronellal content, which yielded an average content of 83.26% with a range of 80.2-85.4%. Weak negative effects were observed on duration of heating and state of division of plant material. Sixteen experiments were conducted on four variables for water distillation. The extracted essential oil yield was increased by 28%. Effects on citronellal content were the same as with steam extraction. Hence, water distillation is better suited for small-scale extraction given the simplicity of the equipment required and the significant gain in extraction yield.

Essential oils from leaves of E. citriodora and E. torelliana pure species and E. citriodora x E. torelliana hybrids, obtained by hydrodistillation, were analyzed by GC and GC/MS. Six oil samples of E. citriodora showed two main constituents (citronellal 57.1-75.4% and citronellol 8-11%) out of 64 identified constituents (> 0.1%). Nine oil samples from E. torelliana contained 78 constituents (> 0.1%) with various main constituents: a-pinene (20.3-78.1%), globulol (20-26%) and citronellyl acetate (55.5%). Six oil samples of E. citriodora x E. torelliana hybrids were of a citronellal/citronellol chemical type (66-76%), like E. citriodora, or a-pinene (24.3-49.5%), or citronellyl acetate (61.4%) chemical type, like E. torelliana.