Supercritical CO2 extraction (scCO2)
scCO2 extraction is a process that takes place in a machine with a high pressure vessel. This uses CO2 (carbon dioxide) as a solvent that takes a mixture phase of liquid and gas at certain pressure (74 bar) and temperature (32 ˚C). By filling the high pressure vessel with a raw material, high pressure compresses the CO2 through the raw material, which dissolves components from the raw material in the CO2. By further decreasing the temperature, the components are separated from the CO2. These components are collected in an extraction vessel. Because the CO2 has been returned to the liquid phase it can be reused again.
Many types of raw materials can be processed in which the combination of pressure and temperature determines which components are extracted from the raw material.
scCO2 extraction gives 2 products:
- Essential oil is recovered at low pressure and temperature of excellent quality. Some examples include: Essential oils from seeds, herbs and flowers
- Extracts, this is under high pressure and this extraction contains all CO2-soluble components: waxes, greases, resin, dyes, etc.
Advantages of this process
- Do not leave any (toxic) residues in extract
- Environment friendly
- Chemically inert
- Extremely suitable for temperature sensitive substances due to low operating temperature
- Extremely suitable for oxidation-sensitive substances due to absence of oxygen
- Components that are normally poorly separated can show a totally different degree of solubility in CO2, which makes it possible for a good separation.
- CO2 is reusable
- Drying technology is significantly cheaper than freeze drying
- An important disadvantage of technology is that it is not a continuous process; Materials must be batched after batch. In recent years, a continuous variant has been developed within the Wageningen UR to put an end to this problem. At the moment, industrialization of the process is still under way.