Essential oils

Essential oils are complex aromatic materials obtained from plants, most often by distillation. Citrus peel oils can also be obtained through mechanical expression.[1]

They contain concentrated mixtures of volatile constituents: substances that readily enter the air. Their fragrance is one expression of chemistry that also participates in the plant’s relationships with other living things.

What does an essential oil contain?

Many essential oils are rich in terpenes and terpenoids. Familiar examples include pinene, limonene and linalool, alongside compounds described as esters, aldehydes, ketones and phenols.

These are overlapping ways of describing molecular structure. Linalool, for example, is both a terpenoid and an alcohol. An essential oil contains a particular mixture of such constituents.

Distillation gathers the volatile portion of the starting material. Most fatty oils, mucilage, tannins and other nonvolatile constituents remain behind.[2,3]

Why plants make this chemistry

The compounds we collect as essential oils already have lives within the plant’s ecology.

Some participate in defense against microbes and herbivores. Others help mediate relationships with insects and other organisms. Research on lavender has connected the regulation of linalool and caryophyllene production with resistance to a bacterial pathogen.[4]

In another example, insect-damaged maize roots release caryophyllene that attracts nematodes which attack the root-feeding pests.[5]

Aromatic chemistry can therefore operate as both a biological defense and a signal. Its significance extends beyond the pleasant or unpleasant smell it has for us.

Properties and caring for the body

Essential oils contribute more than fragrance to botanical body care. Different oils have properties relevant to skin, our experience of breathing, and how relaxed or alert we feel.

Some oils and their constituents have antimicrobial properties; others have been investigated for their influence on inflammation and nervous-system activity. These properties help explain their longstanding place in preparations for the skin and in aromatic practices concerned with comfort and well-being.[6,7,8]

Their aroma is part of this encounter. Applying an aromatic oil brings together its contact with the skin, the experience of breathing its fragrance and our response to that particular smell. Understanding an essential oil means considering these experiences alongside its individual chemistry.

Essential oil, infused oil and perfume oil

An essential oil is a concentrated volatile preparation. An infused oil contains constituents extracted into a base oil. A perfume oil is a finished fragrance carried in oil.

Our Douglas Fir Aromatic Resin Perfume Oil combines Douglas fir resin infused into jojoba with Douglas fir essential oil. The two preparations bring different portions of the tree’s chemistry into the finished fragrance.[9]

Related entries: Distillation; Oil infusions; Absolutes; Resinoids; Sillage, projection & longevity.