In the last blog post we discussed three common methods of essential oil extraction: steam distillation, solvent extraction and cold press extraction. Today I will highlight the more exotic, and less used methods and explain why they might be better for some plants.
I'll never forget having the opportunity to smell two lavender samples each grown in the same field but one was processed using traditional steam distillation the other using CO2 extraction. The difference in the way they smelled was remarkable. I noticed that the CO2 sample just seemed to smell closer to what I expect the original plant aroma was with the edges a little more defined, the aromatic notes a little deeper.
The CO2 extraction process pressurized carbon dioxide becomes liquid while remaining in a gaseous state, which means it is now "supercritical". In this state, it is pumped into a chamber filled with plant matter.
Because of the liquid properties of the gas, the CO2 functions as a solvent on natural plant matter, pulling the oils and other substances such as pigment and resin from the plant. The essential oil content then dissolves into the liquid CO2.
The CO2 is then brought back to natural pressure and evaporates back into its gaseous state, while what is left is the resulting oil.
It is known that the use of high heat in steam distillation changes the molecular composition of both the plant matter and the essential oil. On the other hand, a CO2 extract is closer in chemical composition to the original plant and contains a wider variety of its constituents.
This would certainly explain my experience in testing the two side by side and if you ever get the opportunity to purchase an oil made with the CO2 method I would highly recommend it.
Macerated oils are also referred to as infused oils. They are created when carrier oils are used as solvents to extract therapeutic properties from plant material. The benefit of a macerated oil above a distilled oil is that more of the plant's essence is captured in the distillation process. This keeps the product closer to retaining more of the plant's nutrition.
To make, the plant material is finely cut or crushed the placed in a closed container. The solvent is added and the mixtures stands for 1 week. The liquid is then strained and clarified through a filtration process.
When I first began studying essential oils I purchased herbs from our local herb exchanged and created my own infusions using this method. It was fun to experiment using these oils alone or taking it one step further to make a lotion and knowing I was adding extra plants to my healthy skin regimine.
This method is not commonly used today but it was one of the oldest methods of essential oil extraction that implements the use of fat. By the end of the process the fat (either animal or vegetable) becomes infused with the flowers fragrance compounds.
The process begins with a highly purified and odorless fat which is spread out over glass plates. Fresh flower petals or fresh whole flowers are then placed on the top of the layer of fat and pressed in. They set anywhere from 1 day to 3 weeks depending on the flower that is used.
The final product is the enfleurage pomade which is then washed with alcohol to separate the botanical extract from the remaining fat. When the alcohol evaporates from the mixture, the "absolute" is what is left over.
As you can see, whichever method is used, there is a lot of work that goes into making an essential oil!
Next blog post, we will discuss what to look for when buying essential oils.
Wishing you beauty, balance and wellness! ~Nicole