Separation of phenolic compounds from plant materials using supercritical CO2

In the present work supercritical fluid extraction (SFE) using CO2, was applied for the pre-treatment of mandarin peels. Two-step extraction, combining SFE and conventional extraction, was investigated. During the first extraction step supercritical CO2 at temperatures 25, 40 and 60°C and pressures from 100 to 300 bar was applied to remove the non-polar components from the extracting material. During the subsequent step, conventional extraction of the residual material was performed with 70 % aqueous solution of acetone at optimal operating parameters (60°C, solid-to-solvent ratio 1:50 g/mL) which were investigated in prior extraction experiments. The obtained results confirm earlier findings, that mandarin peels are a potentially good source of flavonoids. Pre-treatment with supercritical CO2 removed the non-polar components and the polar polyphenols became more accessible. Results show that by using SFE with CO2, the polymethoxylated flavones can be separated from flavanones.