Formation of inclusion complexes between cyclodextrins and aromatic compounds under pressurized carbon dioxide

The effects of moisture content, pressure and temperature on the formation of inclusion complexes with cyclodextrins under pressurized carbon dioxide (CO₂) were studied to determine the optimal conditions for the recovery of aromatic compounds after extraction with supercritical or liquid CO₂. The presence of water in the cyclodextrin was essential for the formation of inclusion complex. However, an excess of water lowered the amount of inclusion complex due to inhibition of contact with CO₂. As the pressure increased under a constant temperature, the amount of inclusion complex increased until CO₂ became liquid, where the formation of inclusion complex started to decline. The amount of inclusion complex for modified cyclodextrins was very little, because the cyclodextrins became paste- or candy-like by the addition of a small amount of water.