Formation of solid lipid microparticles from fully hydrogenated canola oil using supercritical carbon dioxide

• A simple and green solid lipid micronization method is reported.
• Supercritical carbon dioxide process is able to produce hollow spherical solid lipids.
• Melting point of the particles decreased by 4 °C after the process.
• Higher pressures and smaller nozzle diameters changed polymorphic form of the solid lipid microparticles from α to β.
• Bulk density of the particles decreased 10-fold compared to the starting material.

A simple and green process based on supercritical carbon dioxide (SC–CO2) technology was used to produce solid lipid microparticles from fully hydrogenated canola oil (FHCO). The effects of pressure (122, 211 and 300 bar) and nozzle diameter (0.1, 0.3 and 14.3 mm) on the particle size, morphology, thermal properties and polymorphism were investigated. Then, the essential oil loading capacity of the particles obtained under optimum conditions was evaluated. Smaller nozzle diameter (0.1 mm) and lower pressure (122 bar) produced spherical particles with narrower particle size distribution and a mean diameter of 1.27 μm. Melting point of all particles decreased to 65 °C from 69 °C for the FHCO. The main polymorphic form of the particles obtained at lower pressures and larger nozzle diameters was α, whereas it was β at higher pressures and smaller nozzle diameters. Essential oil loading efficiency of 96% was achieved when FHCO blended with 40% essential oil was used as the feed material. SC-CO2 process is a promising technology for solid lipid particle formation as delivery vehicles for bioactives.