The nose delight: essential oils November 10, 2015 16:35
Aromatherapists use aromatic essences of plants to promote wellbeing and health of the mind, body and spirit. Such approach aims to strengthen our own healing abilities and help us recover from various ailments. The volatile oils from the aromatic plants can help us feel calmer and less stressed, but also increase energy. So what are essential oils? The original term was ‘quintessential oils’. It relates to the ancient idea of Aristotle that matter consists of four main components: fire, air, earth and water. In addition to those four there was quintessence – the spirit, or life force. Distillation of leaves, flowers or berries of aromatic plants was thought to ‘catch’ their spirit (think of distilled alcoholic spirits such as whisky).
These ‘spirits’, or, as we now know, chemical substances, help the plants to attract bees and other pollinators, compete with other plants and protect them from predators. Flowers are an obvious example of a way of inviting insects with scent. Terpenoids, eucalyptol and camphor produced by sage bushes discourage other plants from growing around them. The Douglas fir tree releases terpenes, components of essential oil, to fight budworm, and each year it changes the composition of these volatile oils so that the budworm cannot develop resistance against them. Finally, terpenes protect the plants from bacteria, viruses and fungi.
A true essential oil has to be extracted from the plant with a physical method, namely distillation (with water or steam) or, in the case of orange peels, mechanical expression (‘cold pressing’). Sometimes plants can also be macerated in water to release the oils. Distillation produces not only the essential oil, but also the hydrolat, or hydrosol, or – my favourite term – flower water. Flower water contains small amounts of the essential oil and can be great in face creams or as a spritzer (e.g. lavender).
Distillation of essential oils: the parts of plant are put inside the still and sealed. Steam or water removes the oils from the plant. The vapours rise through the connecting pipe to the condenser, where they cool down and become liquid – water mixed with essential oil. The oil usually collects on the surface, or sometimes on the bottom of the container. Image courtesy of MAKY.OREL via Wikimedia Commons
If an oil is extracted with solvents, e.g. petroleum ether or ethanol, or with enflourage, it is called an absolute. Oils of delicate flowers such as jasmine or mimosa are obtained this way. The concentration of the solvent in the absolute is between 5 and 10 parts per million and these oils are often used in psychological treatment and with horses. Another, very rare method of extraction is enflourage, or soaking flowers in fat. Absolutes smell quite strongly and are often diluted with alcohol.
By Tara Angkor Hotel (Flickr: Aroma Massage) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
Finally, just to confuse us even more, some oils are extracted with CO2, which becomes liquid under pressure, spreads through the plant and absorbs its aromatic chemicals. In this case CO2 also acts as a type of solvent. These extracts smell very much like the actual plant and sometimes contain more beneficial substances, e.g. frankincense CO2 extract has anti-inflammatory properties that essential oil of this plant lacks.
At the moment the distillation or cold pressing are thought to be the safest methods of obtaining aromatic oils because absolutes and CO2 extracts can contain small amounts of pesticides if they use plants that are not organic. However, it is up to the therapist and perhaps personal taste to decide which type of oil to use.
https://www.naha.org/explore-aromatherapy/about-aromatherapy/, accessed 8th November 2015