The application of the full factorial design and Response Surface Methodology in optimization conditions for essential oils extraction from Lavandula stoechas, Carum carvi and Eucalyptus camaldulensis: Effect of plants particle size on the extraction of essential oils

Abstract

The study applies experimental design to optimize hydrodistillation (HD) parameters in essential oils (EOs) extraction from the aerial parts of three different plants: Lavandula stoechas, Eucalyptus camaldulensis and Carum carvi. Three parameters have been examined: the particle size (Ps) the distillate flow (Q) and the volume of EOs vapor in the Clevenger (Vvap).The ratio of plant mass to the water volume has been kept constant as well as the extraction time. The full factorial design (FFD) gives a first-order model with an R2 > 0.99 for both plants Lavandula stoechas and Carum carvi. According to the Box–Behnken design (BBD) , the EOs yield of Eucalyptus camaldulensis seems to depend on the Vapor volume of the EOs, distillate flow and the particle size and, on the interaction between the Vapor volume and the distillate flow. A second order model obtained by the BBD application on the Eucalyptus camaldulensis plant. The analysis of variance (ANOVA) reveals that the model was significant, as evidenced from R2 of 0.991 and the model F-value of 196, 42. Finally, it seems that for plants whose secretory sites are superficial glandular trichomes, such as Lavandula stoechas leaves (Lamiaceae), or secretory canals, such as Carum carvi seeds (Apiaceae), the particle size has no effect on the extraction yield. On the contrary, the particle size is a limiting parameter in the case of endogenous secretory pockets of Eucalyptus camaldulensis (Myrtaceae).