Modeling the supercritical fluid extraction of essential oils from plant materials

Different types of mathematical models were applied in the last decade to simulate kinetics of supercritical fluid extraction (SFE) of essential oils from aromatic plants. Compared to the extraction of fatty oils, modeling of extraction of essential oils is more complicated due to their potential fractionation, co-extraction of less soluble compounds, and stronger effect of flow pattern on extraction yield, which is connected with solute adsorption on plant matrix. Fitting the SFE models to experimental extraction curves alone usually does not enable reliable selection among the models. Major progress was made when detailed models for the extraction from glandular structures of plants were developed. As the type of glands is characteristic for plant families, the choice of models for SFE of essential oils is substantially facilitated. As the extracts from aromatic plants contain also cuticular waxes and other less soluble substances, and essential oils themselves are mixtures of substances of different solubility in supercritical carbon dioxide, modeling of extraction of mixtures and their fractionation in time deserves more attention.