There are many
different ways to extract essential oils and absolutes (also called
extracted oils). They include:
Warm Oil Infusion
How Are Essential
Essential oils can
be extracted via two key methods: distillation (includes
hydrodistillation) and expression.
How are Absolutes
(Extracted Oils) Extracted?
Absolutes, on the
other hand, can be extracted via solvent extraction or enfleurage,
although enfleurage is rarely performed via the original process any
longer. Enfleurage used to be performed using sheets of fat as a
solvent and was difficult and expensive.
Now, the more common
aromatic product derived from solvent extraction are CO2 extracts.
They differ in chemistry from their related steam distilled essential
oils, but are becoming increasing popular and available, due to
decreased costs in creation. Some holistic practitioners refuse to
use CO2 extracted oils, as they believe some of the CO2 remains
The Practice of
There is evidence
that distillation was practiced throughout ancient times. Based upon
the current interpretation of Paolo Rovesti’s discovery of an
earthenware distillation apparatus, the production or extraction of
oils by means of steam distillation has been performed for
approximately 5000 years.
During the fifth
century AD, the famed writer Zosimus of Panopolis referred to the
distilling of a divine water and panacea. Throughout the early Middle
Ages, a crude form of distillation was used primarily to prepare
floral waters or distilled aromatic waters. These appear to have been
used in perfumery, as digestive tonics, in cooking, and for trading.
References to holy oils extracted from plants appear in ancient
Egyptian, Babylonian, and Aramaic texts.
extensive trade of perfume and sacred oils has been shown to have
occurred in ancient Asia and Greece and Rome, the oils used were not
essential oils, “rather they were obtained by placing flowers,
roots, and other plant material into a fatty oil of best quality,
submitting the glass bottles containing these mixtures to the warming
influence of the sun and finally separating odoriferous oil from the
solid constituents”. This would be a warm oil infusion, rather than
In 900 AD, Avicenna,
the famous child prodigy from Persia who wrote many documents on
botanicals and their uses and instructions for using oils in massage,
was credited with refining the process of distillation by improving
the cooling system.
is still the most common process of extracting essential oils from
botanical material. The advantage of distillation is that the
volatile components can be distilled at temperatures lower than the
boiling points of their individual constituents - these are then
easily separated from the condensed water.
the plant material is placed upon a grid inside the still. Once
inside, the still is sealed, and, depending upon the above methods,
steam or water/steam slowly breaks through the plant material to
separate out its volatile constituents.
constituents rise upward through a connecting pipe that leads them
into a condenser. The condenser cools the rising vapor back into
liquid form. The liquid is then collected in a vehicle below the
Since water and
essential oil do not mix, the essential oil will be found on the
surface of the water where it can be siphoned off. Occasionally an
essential oil is heavier than water and is found on the bottom rather
than the top, such as with clove essential oil.
There are actually
three different steam processes that are described further down. In
all of the methods, steam is used to rupture the oil membranes in the
plant and release the essential oil.
The essential oil
distilling equipment including the condenser, separator and cooking
chambers can all have an enormous impact on the quality of the oil.
As well as, the distillation temperature and pressure. There is a
difference in essential oils produced in a lab grade glass still and
a copper still.
And even if
everything appears correct, the process can still produce oils that
don’t meet the standards set by different herbal organizations and
standardization organizations (such as AFNOR). So essential oil
distillers must have the knowledge and expertise to know how to
produce therapeutic and medical grade essential oils.
The three types
of distillation include:
The plant material
comes into direct contact with the water. This method is most often
employed with flowers (rose and orange blossoms), as direct steam
causes these flowers to clump together, making it difficult for steam
to pass through.
Water and Steam
This method can be
employed with herbaceous, leafy materials. During this process, the
water remains below the plant material, which has been placed on a
grate while the steam is introduced from outside the main still
This method is the
most commonly used. During this process, steam is injected into the
still, usually at slightly higher pressures and temperatures than the
above two methods.
Steam Distillation is So Effective – Boiling Points
The boiling point
designates the temperature at which a liquid is converted to a gas at
a specified pressure. The fundamental nature of steam distillation is
that it enables a compound or mixture of compounds to be distilled
(and subsequently recovered) at a temperature substantially below
that of the boiling point(s) of the individual constituent(s).
contain substances with boiling points up to 200°C or higher,
including some that are solids at room temperature. In the presence
of steam or boiling water, however, these substances are volatilized
at a temperature close to 100°C.
This is a relatively
recent method. It is very similar to steam distillation, except that
the steam comes in through the top rather than the bottom, and there
is a shorter distillation time. It is useful in extracting essential
oils from woody or tough material, or from seeds such as fennel and
Percolation is one
of the newer methods of extraction essential oils. It has been used
successfully in France; however sometimes an emulsion is produced
that can not be separated out, so until it can be further developed
you will not see it on a large scale.
Percolation is often
used to create cocoa nut oil and kaffe nut oil.
distillation separates the volatile oil in different fractions or
portions at various boiling points. This is used in oil refineries
for distillation of petroleum products and is not suited for
therapeutic or medical grade essential oils.
James Sinfield, Two Photographs from the “Cloud Chamber” Series, (2013)
Sinfield, a photographer with a background in theoretical physics has been taking photographs of condensation trails in cloud chambers. The results being the beautiful, abstract compositions seen above.