Separation of antioxidant compounds from high viscous rosemary resins using supercritical carbon dioxide

VISENTIN, A.; CARDARELLI, D.; MATTEA, M.A.; CISMONDI DUARTE, M.; MAESTRI, D.M.

Natal, Brazil

Congreso; PROSCIBA 2010 ? II Iberoamerican Conference on Supercritical Fluids; 2010

Supercritical carbon dioxide was used to obtain antioxidant compounds, mainly carnosic acid (CA), from high viscous oleoresins derived from dried rosemary leaves (Rosmarinus officinalis). A dark green high viscous oleoresin was produced by extracting the leaves with ethanol, a wide accepted solvent in food industry. In the method presented here, objected organic solvents such as acetone or hexane usually applied to treat the above mentioned oleoresin and to obtain high purity CA, were replaced by supercritical carbon dioxide (SCCO2). Nevertheless, the mass transfer of this key compound into the solvent phase (CO2) was hindered by the high viscosity of the starting material. This obstacle was overcome by designing a special nozzle and adjusting the experimental conditions. Pressure was set at 300 bar and temperature at 50°C. As a result of the oleoresin extraction step, the starting material was separated in two fractions. The first one was an insoluble dark green powder, with low concentration of CA (< 5 g/100 g extract) which represented 17 % of the original mass; it was discarded. The other fraction was an orange colored resinous extract, very soluble in SCCO2, with a high concentration of CA (33.4 g/100 g extract). This extract exhibited high antioxidant effect when added to soybean oil. Since the starting material is a fluid phase (oleoresin), the extraction procedure can be carried out in a continuous or semi-continuous way instead of discontinuous as it should be done if the starting material were a solid (herb). This feature makes the procedure very promising toward its application at the industrial scale.