(Ethyl lactate)-gel high pressure CO2 extraction was successfully used as final step for mesoporous gelatine particles preparation. Gelatine spherical microparticles were produced by the water in oil (W/O) emulsion method and further cross-linked with vanillin, to increase its biodegradation resistance. A multi-step solvent exchange of water by ethyl lactate was performed and the gel particles were dried using a semi-continuous high pressure CO2 extraction process. Ethyl lactate was used in this work as an alternative solvent due to high affinity to CO2 and its benign and green nature.

The effect of different parameters, such as solvent exchange temperature and the CO2 extraction operating conditions were investigated. The (CO2 + ethyl lactate) binary mixture composition at the beginning of supercritical extraction process has proven to be an important parameter, considerably influencing textural properties of final dried microspheres. Surface areas of 10 to 300 cm2 g−1 and pore diameters from 10 to 17 nm were obtained as the quantity of CO2 in the mixture decreased.

(Ethyl lactate)-gel high pressure CO2 drying revealed to be a feasible alternative, enabling a “supercritical-control” approach of gelatine microspheres textural properties.