EXTRACTION OF ROSMARINIC ACID FROM BOTANICALS WITH SUPERCRITICAL CARBON DIOXIDE. EFFECT OF THE MODIFIERS ADDED TO THE SOLVENT

This study investigates the extraction of dried leaves and stems of lemon balm (Melissa officinalis L.) with carbon dioxide at supercritical conditions. The target component is rosmarinic acid, a substance with strong antioxidant properties, which gives many useful properties to the extract. Rosmarinic acid has polar structure and its extraction with CO2 only, having non-polar molecule, is not efficient enough. The process efficiency is studied in the presence of two polar modifiers, ethanol and water, added as co-solvents to the basic supercritical fluid. Ethanol is found to be more appropriate as modifier. It boosts significantly the solvent capacity of supercritical carbon dioxide, while water, because of its low solubility in CO2, acts as a separate phase and tends to cover partially the vegetal matrix, thus preserving the solvent from free penetration in the internal structure of the plant.