What is co2 extraction?

Supercritical CO2 extraction is the treatment of a natural, aromatic plant raw material with CO2 (carbon dioxide) in a supercritical state to extract its components.

Carbon dioxide is an odourless inert gas that is a trace component of the atmosphere and a product of natural metabolism. Like water, it is a safe solvent that does not produce residues.

Supercritical CO2 is the state of CO2 when it has the viscosity of a gas and the density of a liquid, making it a good solvent. To reach this state, the CO2 must be compressed and the temperature must be managed in an extremely fine way. The supercritical CO2 drags the molecules into a separator. The pressure is then lowered to separate the CO2 from the extract. The CO2 then becomes gaseous and recirculates until the raw material is completely extracted. The molecules precipitate to the bottom of the separator before being collected.

Extraction with supercritical CO2 is done at a near-ambient temperature (about 32 - 33°C) which allows the organoleptic qualities of the raw materials to be preserved. It is thus said that the extraction is done cold compared to other types of extraction used in particular for essential oils. By way of comparison, extraction by hydrodistillation and steam distillation require temperatures to rise to 100°C
Due to its cold treatment, the result of the supercritical CO2 extraction is close to the "source matrix", i.e. the original plant.

The process is still complex and requires preparation of the raw materials as CO2 extraction is more efficient on dry plants. CO2 extraction has many advantages in terms of environment and quality, but its cost is higher and its yield lower (the two being often linked). Lhe extraction with supercritical CO2 is ecological because it does not generate greenhouse gases or pollutants; it corresponds to what is called green chemistry.

The product of this extraction can be of different natures: vegetable oils (example of the extract of CO2 of Raspberry), antioxidants (extract of CO2 of rosemary), products which are close to essential oils etc

Supercritical CO2 extraction has been known since the 60s and 70s and made its discreet entry into the industrial stage at the end of the 70s, mainly in the food industry. (It will be used in particular to decaffeinate coffee.) It is gradually establishing itself as an alternative to the use of organochlorine solvents and is currently experiencing significant growth because despite its higher investment cost, its quality and reduced environmental footprint make it an alternative of choice in a context where we are increasingly concerned about the planet and our health.
It should also be noted that the implementation of REACH regulations at the European level has brought increasingly strong restrictions to the use of organic solvents for the treatment of plant materials; the objective of REACH regulations is to ensure a high level of protection of human health and the environment against the risks that certain chemicals may pose. These restrictions are particularly important in the food industry, where there is an urgent need for alternatives to the organic solvents traditionally used in the extraction or purification of plant material.