Essential oils are complex mixtures of more than 300 identified chemical compounds and possibly more that are yet to be discovered. They are volatile and low molecular weight compounds.
Their chemical composition is affected by intrinsic (plant-related) factors like plant genetics, climate, soil type, agricultural practices, altitude and extrinsic factors like harvesting time and extraction method. Due to their volatile nature, Essential Oils are analysed using gas chromatography along with other methods like mass spectrometry and infrared spectroscopy.
The main constituents of Essential Oils are two types of compounds which are derived from two different pathways
They are divided into two main categories:
- Hydrocarbons which are Monoterpenes, Sesquiterpenes and Diterpenes. Monoterpenes are present in almost all Essential Oils. They are smaller and lighter, so they get easily absorbed. Sesquiterpenes are heavier than monoterpenes and carry their own benefit at the cellular level by binding with the receptors.
- Oxygenated Compounds of Terpenes (Terpenoids) which are categorized into different families like alcohol family
(e.g. geraniol, linalool), aldehyde family (e.g. cinnamaldehyde), ketone family ( e.g. menthone), phenol family
(e.g. eugenol, thymol), acid family and esters family (e.g. terpinyl acetate, linalyl acetate).
Non-terpenoid compounds which include phenylpropanoids, fatty acids and their esters, Sulphur and Nitrogen containing compounds.
Essential Oils possess properties like unique aroma, antioxidant properties, antibacterial properties, anti-inflammatory properties, insect repellent ability and also offer numerous other health benefits.
- A single Essential Oil can constitute hundreds of these different constituents!
- Many Essential Oils share a similar chemical composition but they have totally different aromas. This is because of the different proportions of these constituents that make them.