2.1 Introduction
To be a good aromatherapist,
it is important to understand the science that exists behind aromatherapy. It will help you to not just
improve your own understanding so that you are able to make effective blends,
but you can guide your clients too. Although essential oils are
natural, they still have chemical components. Understanding these components
are vital when it comes to blending as if you mix two oils and the components
react against one another, it will reduce the effectiveness of your blend. In the main, primary components
include:
Carbon
Oxygen
Hydrogen
The main building block is an
isoprene. This is actually shortened from isoterpene.
The chemical formula is: CH2=C(CH3) CH=CH2
There's no actual reason for you
to memorize the chemical formula unless you want to, it's just so you
understand that it is carbon (C) and hydrogen molecules (H). The categories of constituents
depend on how the isoprenes are arranged into chains. Then, it depends on how
the carbon and hydrogen are added together which enables the oil to 'act'.
Usually an essential oil consists
of aromatic rings and the branched chain of approximately 5 carbon compounds.
The set of an essential oil will be determined within the rings. So, it depends
on the number of the carbon atoms found – three or even as many as five. There
are lots of variables however - growing conditions, the species of plants and
extraction method used.
2.2 There are two main types of
basic compounds:
Terpenes
Terpenes are a large group of
unsaturated, atomic hydrocarbons and they have space for more hydrogen atoms Oxygenated compounds These compounds are responsible
for the character of the oils. Oxygenated compounds include ketones, aldehydes,
acids, phenols, coumarins and esters. When working with blends, the oils must
have a similar make-up which enables them to work favourably with each other.
You'll know the difference when you blend oils which react unfavourably. It is also important to
understand primary compounds in respect of safety.
2.3 Problematic compounds
Ketones
When there are large
concentrations of ketones, they may irritate the skin and so these oils are
best used in a diffuser or, dilute them heavily.
Phenols
Oils which contains phenols
should only be used for a short period of time as they can leave a residue in
the liver. When these oils are used regularly, there is the risk of toxicity. Here's a brief introduction to
the components:
Hydrocarbons include:
Aliphatic chains – terpenic
hydrocarbons can be recognised by their name as they end in 'ene'. These provide slightly antiseptic, bactericidal, expectorant, analgesic or stimulating qualities. Sesquiterpenes – antiseptic,
bactericidal, anti inflammatory and calming. Some are analgesic and/or
spasmomytic.
Diterpenes – expectorant,
purgative, anti-fungal and anti-viral. Some may balance the hormonal system.
Alcohols – have a strong
bactericidal and antiviral effect. They are stimulating. Usually without skin
irritation and are non-toxic.
Phenols – antiseptic and also
bactericidal. They stimulate the nervous system and also the immune system. Can
be toxic to the liver.
Esters – rarely occur alone in
essential oils but have anti-spasmodic, sedative and anti-depressant
properties.
Aldehydes – anti-viral,
anti-inflammatory, calming, but can cause skin irritation.
Ketones – some are analgesic,
anti-coagulant or stimulating. Should be used with care if the client is
pregnant.
Organic acids and esters –
anti-fungal, anti-inflammatory, calming, tonic and anti-spasmodic. Free from
toxicity.
Oxides – eucalyptol known to be
an expectorant and mucolytic. Can cause skin irritation.
Lactones – only present in
expressed oils and, some absolutes. As an example, jasmine oil. Known to be
mucolytic, temperature reducing and an expectorant. May cause photo toxicity.
Coumarines and forocoumarines –
coumarins are anti-coagulant hypotensors.
They are uplifting and also sedative.
Furocoumarinez are known for photo toxicity so these are oils which should not be used prior to sunbathing and this includes sunbeds. They have anti-viral and
anti-fungal properties.
2.4 Prices
Price The prices of some of the
essential oils may seem incredibly expensive when you first start out and so it
pays to shop around and check out the average price prior to purchasing. You won't need to invest in a
complete range at first, but gradually build up your stock. Although some
prices per bottle may seem extortionate, it is because of the availability of
the plant material or the process for extraction.
When you consider the cost of
rose petals and the amount needed to produce just a few pounds of pure
essential oil, you will understand why rose oil is more expensive. As such, it
is often commonly blended with other oils. This is because roses are less
versatile and the oil can only be extracted from the petals. Other plants are
more versatile and it is possible to extract oil from the flowers and leaves or
in the case of oranges, even from the peel. As an example; eucalyptus oil is
less expensive to produce because it is easier to obtain a higher yield of oil.
2.5 Growing conditions
Growing conditions will
also have an impact on costs and quality. So in some years, essential oils
may be of a better quality than in others. Oils that have been derived from
plant flowers must be extracted quickly after harvesting whereas by contrast,
oils that would be obtained from roots or seeds can be stored.
Concrete
When we talk of concrete, we mean
those that come from the vegetative parts of plants so, the roots, herbs,
flowers, leaves as opposed to fruit. Usually, this means exposure to solvents
as opposed to a steam or distillation process. This is important and necessary
because the oils will be damaged if alternative processes used. The advantage of using solvents
means that the extracted oils are as close to the natural scent as possible.
Some plants such as lavender can be extracted by either method. Concrete will
be less volatile and more aromatic than essential oils on their own and are
more stable. They contain usually half wax and half volatile oil.
Resinoids
These are prepared from natural
resinous material through hydrocarbon solvent extraction such as petroleum,
ether or hexane. Resinous materials include: peru balsam or benzoin, resins
including mastic and amber, oleoresins – copaiba balsam and turpentine and oleo
gum resins including frankincense and myrrh. Note: resinoids are also used as
a fixative within the perfume industry.
Absolutes
Derived from concrete via the use
of solvents, the oil is treated to several exposures so as to remove the
maximum amount of wax as possible, but some will remain. Absolutes are
subjected to 2 molecular distillations so to remove ethyl alcohol and any
leftover traces of (non-volatile) matter. Although remaining traces may be
minimal, these should not be used in therapy.
MODULE SUMMARY
In this module, you learnt how
important it is to understand the science that exists behind aromatherapy. Understanding the components is
vital when it comes to blending. The oils must have a similar make up, which
enables them to work positively with each other. Otherwise, the effectiveness
of your blend may be affected. The module also discussed the
properties and risks of the various compounds . In the next module, we look at
how to choose essential oils.
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