While essential
oils are certainly an essential
part of aromatherapy, contrary to what some people think, the term
"essential", in this case,
does not mean "being a necessary part of".
Instead, in aromatherapy,
essential oils are the oils extracted from the "essence" of a plant, or
those parts that contain the plant's aroma molecules.
The number of possible extraction methods can be confusing to the
novice, However, using different methods of extraction guarantees that
the highest concentrations of oils can be extracted.
Essential oils are
gathered from many different types of plants and many different parts
of those plants. Flowers, fruits, herbs, stems, roots, leaves, buds,
blossoms, seeds, nuts and even tree bark produce some of the most
aromatic and therapeutic essential oils.
Essential oil extraction
methods fall under three main categories: expression, solvent
extraction and distillation.
The following is an overview of the common extraction processes and
methods.
Expression
The expression method of essential oil extraction does not involve the
use of a heat source, as does distillation.
Expression is the method
commonly used to extract oils from the rinds of citrus. In earlier
times, rinds were squeezed by hand and a sponge was used to collect the
essential oils. The fruit would be removed and then the rinds along
with the pith would be soaked in water to make them easier to work
with. They'd then be turned upside-down.
Turning them upside-down
caused the cells containing the oils to break apart. Once broken, the
oils would drip out and soak into a nearby sponge. When the sponge
became saturated, the oils were squeezed into a container so they could
be decanted.
Ecuelle a Picuer
Another expression method involved sticking pins into the skins of
fruit for the purpose of damaging the cells that contain the essential
oils. The apparatus used had a built-in container for collecting the
oils and the other parts of the fruit that ended up in the collection
area. The final steps involved separating the essential oils and
decanting them. This is called the ecuelle
a picuer method.
Machine
Abrasion
Those previous methods were quite labor-intensive processes,
and thankfully, technological advances led to the invention of machines
to do this sort of tedious work. Nowadays, oils from rinds are
extracted using centrifugal force. This rapid process is called Machine Abrasion.
Cold Pressed
This method of expression extraction of essential oils is
commonly used to extract essential oils from nuts and seeds and from
the rinds of citrus.
Essentially, no pun
intended, mechanical pressure is used to force the oils out. The oils
extracted in this way contain water, but this water will, in time,
evaporate, leaving just the essential oils. The downside of using this
extraction method is that the cold pressed oils spoil more quickly than
those extracted using other methods. That's why, to eliminate waste,
it's important to purchase these types of essential oils in small
quantities.
