What is the difference between supercritical and subcritical CO2 extraction?
CO2 is a unique solvent because its solvency power can change by simply adjusting the temperature and pressure during the extraction. When the pressure and temperature of the CO2 are above 1083psi AND 88F, the CO2 is considered supercritical. If the temperature is dropped below 88F the CO2 changes to a liquid and referred to as subcritical.
Supercritical CO2 (SCCO2) extraction is a strong solvent and can extract all of the lighter (volatile oils, light waxes) and heavier molecular weights (heavy waxes, lipids, fats, paraffin) to produce very large yields. At very high temperatures (above 120F) and pressures (5000psi) it will extract chlorophyll as well. Subcritical CO2 is a weaker solvent and generally pulls out just the lower molecular weights, and has correspondingly lower yields and higher extraction times.