High pressure extraction of vitamin E-rich oil from Silybum marianum

The efficiency of high pressure extraction in the production of oil with a high concentration of vitamin E, from seeds of Silybum marianum, was investigated. The solvents used in extraction were liquid or supercritical carbon dioxide and liquid propane. Operating parameters were 100, 200, 300 bar and 25, 40, 60 and 80°C for CO2 and 60, 150, 200 bar and 40, 60 and 80°C for propane, respectively. The influence of process parameters on the total yield of extraction, vitamin E composition and acid value of the extracts was investigated. Results were compared with those obtained for conventional extraction with organic solvents (n-hexane, petroleum ether, dichloromethane, chloroform). The mathematical model based on the adsorption–desorption equilibrium of oil from solid tissue, the diffusion of oil to the surface and mass transfer through external film into the bulk, described the experimental extraction results well.