Solute-Matrix and Solute-Solute Interactions During Supercritical Fluid Extraction of Sea Buckthorn Leaves

AbstractIn this work, the SFE was applied to extract selected medicinal substances from sea buckthorn (Hippophae rhamnoides L.) leaves at different conditions (pressure 20-28MPa, temperature 40-60°C and ethanol concentration in CO2 0-6.9wt. %) influencing solvent power of CO2. Interest was focused on the leaf oleoresin (total extract) and its minor components (fat soluble vitamins and carotenoids). The yield of polar component was still steadily increasing at the moment when the extraction is almost finished as non-polar components are exhausted and the increase in total extract is very low. Out of the operation variables, the ethanol concentration in CO2 showed the strongest effect on the extraction. The final yields of polar components were increasing with rising ethanol concentration in CO2. The extraction of non-polar components (vitamins and β-carotene) and polar lutein was synchronised with oleoresin, whereas the extraction of non-polar lycopene, a component strongly affected by entrainer, was not influenced by the extraction of oleoresin. The solute-solute interactions were expressed either as a delay of the initial extraction period for some poorly soluble components against the more soluble ones or, on the contrary, as a synchronous extraction of the components similar in structure