Power of Solvation
CO2 is a good extraction solvent for lipophilic and hydrophobic components. Which is why its popular with natural product extraction.
However there are times when you’re interested in products that are more polar.
The polarity of the CO2 can be adjusted with the addition of a more polar solvent like ethanol.
Small percentages of more polar solvents can have a significant effect on which components are extracted. It can also help reduce the pressures required to extract components such as polyphenols.