Supercritical antisolvent particle precipitation and fractionation of rosemary (Rosmarinus officinalis L.) extracts

The simultaneous fractionation and precipitation of an ethanolic extract of rosemary (Rosmarinus officinalis L.) using supercritical carbon dioxide anti-solvent technique was studied, with the target of separate in two different fractions the key antioxidants of rosemary (i.e. rosmarinic acid, carnosic acid and carnosol). The effect of pressure and temperature on the fractionation process was investigated, together with the morphology and particle size distribution of the precipitates. Additionally, the chemical composition of the oleoresins were analyzed and reported. In the range of pressures (9-20 MPa) and temperatures (313-333 K) used in this work, the precipitates presented a 2-3 fold enrichment of rosmarinic acid, while carnosic acid and carnosol were concentrated (2-3 fold enrichment) in the oleoresin fractions. Furthermore, in general, oleoresins presented higher antioxidant activity than precipitates. Particles produced with a nozzle of diameter 101.6 mu m were smaller and more spherical with increasing pressure (mean value 4-10 mu m at 20 MPa) and decreasing temperature.