Supercritical carbon dioxide separation of bergamot essential oil by a countercurrent process

The efficiency of separation of bergamot essential oil, performed by a countercurrent column filled with Raschig rings and using supercritical carbon dioxide as partition solvent, is affected by various parameters. In the experiments explained in this work, the direct effect of CO2 density was shown and the ratio between the amount of oil loaded to on the column and the amount of CO2 used were discussed. The conditions that produced extracts with a similar volatile fraction composition of starting material and with a high yield (more than 80% of recovery) were those with a low feed:solvent ratio; the lowest bergaptene content was obtained at low CO2 density or at high feed: solvent ratio. A good result was observed at a CO2 density of 206 g/dm3 (8 MPa of pressure and a temperature gradient of 46-50-54 °C and a feed:solvent ratio of 9.4-9.6; in this separation, a yield of 74-77% and a bergaptene content lower than 0.01% was measured.