Decaffeination of yerba mate (Ilex paraguariensis) by pressurized liquid CO2 extraction: A feasible process?

This work introduces a pumpless high-pressure Soxhlet cross-current solid-liquid extraction method using liquid CO2 and hydrated ethanol for studying the decaffeination of yerba mate. By combining experimental results with thermodynamic modelling, a comprehensive evaluation of the impact of the co-solvent composition is achieved. It is observed that an ethanol/water mixture with a specific composition of 85 wt% is optimal under mild operating conditions (283 K and 4.5 MPa) for extracting caffeine from chopped yerba mate leaves with a negligible co-extraction of caffeoyl derivative antioxidants. The obtained selectivity, together with the phase equilibrium simulation, provide evidence of the significant potential of liquid CO2 extraction as a decaffeination alternative for yerba mate. Thus, high-pressure Soxhlet extraction serves as simple technique to access valuable experimental information with potential for the conceptual design of further scalable semi-continuous processes. [Display omitted] •Yerba mate impregnated with hydrated ethanol is extracted using near-critical CO2.•The decaffeination process is conducted at 283 K and 4.5 MPa.•A maximum extraction yield of 2.68 wt% is achieved in the separation process.•GCA-EoS is used to evaluate the impact of co-solvent composition on the extraction.•Pressurized liquid CO2 shows significant potential for yerba mate decaffeination.