With so much talk everywhere about
essential oils, one might wonder where do they come from?
It’s easy to understand that they are
natural products obtained from plants and trees. But, how do plants go from
being a plant to essential oils?
In this post, we will describe some of the
methods that can be used to extract essential oils. Don’t worry, we won’t get
too technical, we promise.
Essential oils are not all obtained from
the same parts of the plants. Different plants produce oils in different parts,
and because of this, not all oils are extracted using the same method. Here are
some of the most commonly used methods for some of the most common essential
By far the most common method for most
oils, steam distillation might sound super fancy, but it’s really not. Dry
Steam is passed through plant material. The heat causes the volatile substances
in the plant, i.e. the essential oils, to vaporize.
The resultant volatile compounds are then
condensed and collected in receivers. The idea itself is quite simple. In fact,
it is a method that has been tried and tested for centuries. Historically,
steam distillation has been used for many years for extracting the oils from
plant materials, although mainly in the perfume industry and for cookery. Other
distillation methods are also often used, but steam is the most common as it
provides the best results.
Steam distillation is used for oils that
are extracted from leaves, flowers, wood, bard, roots, seeds, or even peels,
and is the method for extracting many of the most common essential oils such as
lavender, tea tree, patchouli, peppermint, and eucalyptus.
Expression aka Cold Pressing
Most commonly used for citrus peels, cold
pressing involves squeezing the plant materials to rupture the oil glands,
which in turn releases the oils. It is a method that predates even distillation
processes and was the commonly used method for all essential oils before
distillation became common practice. As mentioned before, this method is mainly
used for citrus peel oils such as orange, lemon, blood orange, etc.
Sometimes, a plant material, mainly
flowers, might not contain enough volatile oil that they can be squeezed out
using cold pressing, but might also be too delicate to survive the high
temperature steam distillation method that could easily alter the chemical
property of the oil itself.
In this method, a solvent such as hexane
or supercritical carbon dioxide is used to extract the oil. When these solvents
are introduced to the plant material, an extract, known as concrete, is
produced which is a mixture of essential oil, waxes, resins, and other oil
soluble plant material. A second solvent is then used to extract the essential
oil from the concrete.
The main advantage of this method over
something like steam distillation is that the plant materials don’t have to
suffer through the high temperature and pressures of steam distillation,
resulting in a more fragrant and purer oil. It is a method that has
historically been used for producing stronger perfumes. This method is very
commonly used to extract oils from delicate flowers like rose and jasmine.
These three aren’t the only methods
available, and going into the details of each method might take ages. So, we
will leave it at that for now. The chemistry and physics behind the extraction
of essential oils is quite fascinating, even if it is beyond the scope of one
blog post. That said, we hope that his post has given you at least as basic
idea of what goes into essential oil extraction.