ABSTRACT Extracts from the leaves of Psidium guajava L have been studied due to their importance as a source of natural antioxidant components with possible applications in the pharmaceutical and food industries. In this work, the sequential use of steam distillation and supercritical fluid extraction was studied to obtain the essential oil from the leaves and non-volatile compounds from the residue. The non-volatile compounds were obtained by CO2 supercritical extraction. Experiments were performed in a automated pilot-scale extractor at constant pressure of 15 MPa, at 313 K and 333 K in three different flow rate conditions. The analysis of the essential oil with GC-MS identified E-caryophyllene, β-selinene1, α-selinene, selin-11-en-4-α-ol and E-nerolidol as main compounds. Antioxidant activity was observed in all extracts. The experimental extraction curves were compared to simulated ones predicted by a mathematical model based on mass transfer principles with two adjustable parameters. The model used fitted accurately the experimental data.

Abstract The greatest obstacle in simulating processes involving essential oils is the small number of thermo-physical properties and experimental data available in the literature. In this work, thermodynamic models are investigated in order to predict such properties, which are requisites for the modelling and simulation of the Eucalyptus essential oil batch distillation processes. A group contribution method was used to predict the vapor pressure (CSGC-PVR) when experimental data were unavailable. Regarding the activity coefficients, a fully predictive model based on quantum calculations (COSMO-SAC) is used. Moreover, this work also uses those predicted properties in a dynamic model, capable of describing the fractionation process by batch distillation. The simulations were performed in the equation-oriented simulator EMSO to demonstrate the feasibility of the proposed method. The proposed method suggests a simulated recovery of a 98.89% eucalyptol fraction from E. globulus and a 98.53% citronellal fraction from E. citriodora.