When it comes to essential oils, many people are familiar with them. The extraction of essential oils can be traced back to ancient Egypt.

Cleopatra, the Queen of Egypt, used "perfumed oils" for skincare, investing heavily in creating "perfumed oils" from plants in her "perfume garden." Her favorite was jasmine perfume, and by "perfumed oils" and jasmine perfume, she meant essential oils.

However, why do plants produce essential oils? What chemical components do essential oils contain? And how are essential oils extracted from plant materials? Today, let's explore the secrets behind essential oils.

Advertisements for essential oils are everywhere, but what exactly are the constituents of essential oils?

Essential oils are a class of secondary metabolites found in different parts of plants such as flowers, leaves, stems, roots, or fruits. They are typically volatile aromatic oily liquids at room temperature, mainly composed of compounds such as terpenes, alcohols, phenols, aldehydes, esters, and ketones.

Each essential oil contains various chemical components, ranging from a dozen to over a hundred, and the content of each component varies significantly depending on factors such as plant variety, origin, habitat, and growth period.

For example, the most famous lavender essential oil contains mainly linalool and linalyl acetate. The beloved rose essential oil contains a significant amount of geraniol and citronellol. These compounds are also important aromatic components of essential oils. Compounds such as camphor, camphene, and eucalyptol often emit a cool scent in essential oils.

If the content of camphor in the essential oil is too high, it will affect the aroma and decrease the quality of the essential oil. These unique aromatic compounds with distinctive scents and effects are combined in different proportions to form the unique recognizable fragrance of each essential oil.

If you want to know the chemical components contained in a particular essential oil, you need to use a Gas Chromatography-Mass Spectrometry (GC-MS) instrument. By using normal alkane mixtures as standards and calculating and comparing retention indices, you can determine the structure of the compounds from the database.

Interestingly, although the chemical compositions of various essential oils differ significantly, many chemical components can be found in multiple plant essential oils due to similar synthetic pathways. For example, common compounds such as terpenes, limonene, linalyl acetate, pinene, and caryophyllene are present in various plant essential oils.

The reason why essential oils have effects such as antibacterial, anti-inflammatory, sedative, and scar lightening is also because they contain these biologically active chemical components.

Most of the compounds in essential oils are small molecules with molecular weights ranging from tens to hundreds, making them easy to volatilize. Therefore, essential oils are generally stored in sealed, opaque containers, and the lid should be tightened as soon as possible after each use, with the number of openings minimized.

In addition to being used in daily life, essential oils also have other development and utilization values. For example, some plant essential oils have insecticidal and herbicidal effects and can be developed into biopesticides.

Since essential oils are natural components produced by plants and can be degraded by microorganisms in nature, they avoid the problem of environmental pollution caused by chemical pesticides, making them very suitable for sustainable development needs.

So why do plants produce essential oils?

Some plants, such as flowering plants, produce essential oils to attract insects for pollination. Plants in the pine family produce essential oils to repel pests and inhibit the growth of pathogens. Some plants, such as Italian ryegrass and prickly ryegrass in the daisy family, can produce chemical compounds that inhibit the growth of other plants.

They release these compounds into the air, transmitting them to nearby plants, and causing poor growth in neighboring plants. This is called allelopathy and is one of the essential invasion strategies for many foreign plants.

So you see, since plants cannot change their position like animals, they have to rack their brains to produce various biologically active secondary metabolites, and essential oils are just one of the specific physiological and ecological functions of these secondary metabolites synthesized by plants.