Supercritical fluid extraction of bioactive compounds from Macela (Achyrocline satureioides) flowers: Kinetic, experiments and modeling

The flowers of Macela (Achyrocline satureioides) were extracted by supercritical fluid extraction (SFE) using ethanol as co-solvent. Several experiments were performed at the temperature of 303.15 K and 318.15 K and pressure of 20 MPa and 30 MPa. These experiments were accomplished with various compositions and mass flow rate of supercritical solvents in 420 min. The extracts from each experiment were analyzed by spectrophotometry and gas chromatography, therefore, the amount of gallic acid and quercetin and the composition of the essential oil were determined. In the second part of the paper, experimental extraction data were correlated using two kinetic models based on mass transfer equations. The adjustable parameters of the models have been determined using genetic algorithm optimization technique. The results of the two models were compared to experimental data by a well-known statistical criterion, average absolute relative deviation. As expected, the lowest deviation between experimental and correlated data was obtained by the model with more adjustable parameters.