What features of CO2 SCFE make it an ideal process in the extraction of essential oils used for aromatherapy?
The fact that CO2 SCFE is carried out at relatively low temperatures is a huge plus point when it comes to essential oil extraction for the purpose of aromatherapy. Such process parameters avoid the thermal degradation of the required essential oil.Furthermore, because the dissolution and separation action of CO2 SCFE is based on pressure difference, purity of the extracted essential oil is largely maintained.
Aromatherapy is gaining popularity on account of its capacity to deal with a host of disorders. Also called essential oil therapy, it administers essential oils using four techniques:
- Massage
- Direct inhalation
- On the skin application through lotions and bath salts
- Indirect inhalation
Some of the other methods used to extract essential oils are as follows:
- Hydrodistillation
- Solvent extraction
- Cold press extraction
- Maceration
All distillation processes employ heat. Hydrodistillation is no exception. High temperatures vapourize a certain part (molecule) of the raw material. Later, the same molecule, also called target molecule, is condensed. The idea is to separate the target molecule in its pure form since each molecule has a unique boiling point. However, the use of heat creates its own set of issues, namely thermal distortion.
Speaking of solvent extraction, it leaves behind residues in the extracted essential oil. Again, this affects purity. The solvent is first used to dissolve the essential oil molecule from the raw material. Subsequent filtration removes the unwanted solid material from the solution. Thereafter, evaporation or purging separates the solvent from the essential oil molecule. The solvent however does not completely separate from the molecule. For example, seed oil obtained via solvent extraction, employing hexane as the solvent, leaves behind traces.
Essential oils stimulate the human body into releasing the endorphins and oxytocin hormones. The action of endorphins is geared towards mitigating pain and stress. Oxytocin plays an important part in childbirth. It is also a kind of a social hormone for it plays a role in influencing social behaviour such as trust, recognition, and anxiety. It is these effects of the application of essential oils that aromatherapy makes use of.
Now, essential oils will demonstrate these benevolent health effects only when available in their pure form. And, as mentioned, hydrodistillation and solvent extraction negatively affect the purity of the essential oil being extracted.
On the contrary, carbon dioxide extraction of essential oils relies on pressure differences - dissolving the essential oil molecule in supercritical carbon dioxide (sCO2) at comparatively high pressure and separating it from sCO2 at low pressure. This way, it extracts only the essential oil molecule with little or no inclusion of other molecules in the raw material.
And because the process pressures and temperatures are relatively low, the issue of thermal distortion is nipped in the bud. The critical pressure of carbon dioxide is 73.9 bar, which is not very high. Then again, the critical temperature of CO2 is 31.1 deg-Celsius, which is around the room temperature.
Seen in this light, the CO2 SCFE process is ideal for extracting essential to be used for aromatherapy.
