Volatile oil (Essential oil)

Volatile oil (Essential oil)

An essential oil is a concentrated hydrophobic liquid containing volatile chemical compounds from plants. 

Essential oils are also known as volatile oils, ethereal oils, aetherolea, or simply as the oil of the plant from which they were extracted, such as oil of clove. 

An essential oil is “essential” in the sense that it contains the “essence of” the plant’s fragrance. 


Essential oils are generally extracted by distillation, often by using steam. 

Other processes include expression, solvent extraction, absolute oil extraction, resin tapping, wax embedding, and  cold  pressing.  

They are  used in  perfumes,  cosmetics,  soaps  and  other products,  for flavoring food and drink, and for adding scents to incense and household cleaning products. 

Essential Oils should not be confused with Perfume, Fragrance, etc. as the latter usually include pure chemical components whereas essential oils are derived from plants.


Most common essential oils such as lavender, peppermint, tea tree oil, patchouli, and eucalyptus are distilled. 

Raw plant material, consisting of the flowers, leaves, wood, bark, roots, seeds, or peel, is put into an alembic (distillation apparatus) over water. 

As the water is heated, the steam passes through the plant material, vaporizing the volatile compounds. The vapors flow through a coil, where they condense back to liquid, which is then collected in the receiving vessel. 

Most oils are distilled in a single process. 

The recondensed water is referred to as a hydrosol, hydrolat, herbal distillate, or plant water essence, which may be sold as another fragrant product. 

Hydrosols include rose water, lavender water, lemon balm, clary sage, and orange blossom water. 

The use of herbal distillates in cosmetics is increasing. 


Most citrus peel oils are expressed mechanically or cold-pressed. 

Due to the relatively large quantities of oil in citrus peel and low cost to grow and harvest the raw materials, citrus-fruit oils are cheaper than most other essential oils. 

Lemon or sweet orange oils are obtained as byproducts of the citrus industry. Before the discovery of distillation, all essential oils were extracted by pressing.

Solvent extraction

Most flowers contain too little volatile oil to undergo expression, but their chemical components are too delicate and easily denatured by the high heat used in steam distillation. 

Instead, a solvent such as hexane or supercritical carbon dioxide is used to extract the oils. 

Extracts  from  hexane  and  other  hydrophobic  solvents  are  called  concretes,  which  are  a mixture of essential oil, waxes, resins, and other lipophilic (oil-soluble) plant material.


Essential oils are often used for aromatherapy, a form of alternative medicine in which healing effects is ascribed to aromatic compounds. 

Aromatherapy may be useful to induce relaxation, but there is not sufficient evidence that essential oils can effectively treat any condition. 

Improper use of essential oils may cause harm including allergic reactions and skin irritation, and children may be particularly susceptible to the toxic effects of improper use.


Terpene,  any  of  a  class  of  hydrocarbons  occurring  widely  in  plants  and  animals  and empirically regarded as built up from isoprene, a hydrocarbon consisting of five carbon atoms attached to eight hydrogen atoms (C5H8). 

The term is often extended to the terpenoids, which are oxygenated derivatives of these hydrocarbons.

The true terpenes are usually grouped according to the number of isoprene (C5H8) units in the molecule: monoterpenes (C10H16) contain two such units; sesquiterpenes (C15H24), three; diterpenes (C20H32), four; triterpenes (C30H48), six; and tetraterpenes (C40H64), eight.

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