Essential oil, is an aromatic oil, which is extracted from naturally occurring plants. They are classified based on their notes, just like musical notes. Essential oils with light notes will fade away within a short period of time.
Medium note may last several hours, and base note, can last for several days. They are also classified, by their chemical molecular structure. For example, aldehydes are such chemical groups. Benzldehyde has a typical sweet almond odour. It is prepared synthetically, from Cinnamldehyde with Cinnamon odour. Another aldehyde is Heptaldehyde, which is used in preparing artificial Jasmine perfumes. They are synthesized from castor oil.
But, essential oils are, one hundred precent, natural material, extracted from plants. Some essential oils are extracted from flowers such as Rose, Jasmine, Lavender, Lilac, Tuberose and Geranium. These oils are normally extracted using solvents, usually petroleum based, such as n- Hexane. In order to avoid such petroleum usage in extraction of aromatic materials, a new technique called ‘Super critical extraction’ method, was developed. In this process, no petroleum solvents are used. They use inert solvents such as liquid carbon dioxide.
Liquid carbon dioxide remains in a liquids state at a very low temperature. Such process allows extraction of perfumery components from flowers, at very high purity. Due to high cost of this process, only expensive flowers such as Jasmine and Tuberose are used. Some essential oils with base note, which are also used as food flavouring agents, such as Ginger oil, Cinnamon, Clove and Coriander, use this process. These oils have applications, not only in Aromatherapy formulations, but also in food flavours.
Some oils such as Lemon and Sweet Orange are obtained by expression of Lemon or Orange peels. They are by-products of Citrus industries. Other oils such as Sandalwood, Rosewood, Eucalyptus oils, are obtained from steam distillation. Some essential oils are obtained from seeds such as Almond, Anise and Nutmeg.
Essential oils are volatile in nature, and they are immiscible with water. They need to be blended with a solvent to formulate an Aromatherapy compounds. Mostly, they use Ethyl alcohol or Absolute alcohol, as the solvent, which has necessary physical properties, to act as a carrier. They can easily spread the fragrance by evaporation. They also use base oils, such as Olive oil and coconut oil.
Most of the essential oils are toxic, and are not suitable for oral consumption. Some of them, such as Tea tree oil, have low flash point, and it is classified as ‘Inflammable’. The purity of essential oils are analytically measured, using instruments, like Spectrophotometer and Chromotography.Some of them are classified under FD&C (Foods, Drugs and Cosmetics), and some they are classified under ISO standard. The packaging and labelling are covered under the above standards.
