Essential Oil Extraction

It takes a huge amount of plant material to produce essential oil. To generate one kilogram of the following pure es­sential oils you need:

  • Lavender: 200 kilograms of fresh lavender flowers
  • Rose: 3.5 metric tones of Rose petal
  • Lemon: 3,000 lemons

This explains the high cost of pure es­sential oils.

Essential Oil Extraction From Plants

Essential oils can be obtained from many different parts of a plant:

  • flowers
  • leaves
  • twigs
  • roots
  • bark
  • wood
  • seeds
  • fruit
  • rind
  • resin

Essential oils are manufactured by the plant using energy from the sun, air, rain and soil. 

Plants that contain aromatherapy oils can be found in many parts of the world :

  • Lavender from the Mediterranean region
  • Rose from Bulgaria
  • Tea-Tree and Eucalyptus from Australia
  • Spice oils from the far east
  • Pine from Siberia ...

Steam Distillation

The purest method of essential oil extraction is called distillation.

Steam is passed through the plant material to extract the oil. This mixture of oil and water is then cooled and turns back to water.

The essential oil then usually floats on top of the water (or sinks to the bot­tom for heavy oils such as clove) and this oil is simply skimmed off.

Further information on steam distillation may be found here.

Steam Distillation

Enfleurage

Enfleurage is the second method of essential oil extraction.This is not to be confused with Effleurage, which is a massage stroke.

Enfleurage is used to extract oil from delicate flowers. It involves laying  the flower on sheets of glass coated with fats. The essence is extracted into the oil. The old petals are removed, and new ones laid on.

This process may last several weeks, until the fat can absorb no more essence. The fat is then dissolved in alcohol, leaving a concentrated form of essential oil known as an absolute.

SOLVENT EXTRACTION

Solvent extraction is more common these days.

Volatile solvent (benzene, chlorate of methylene, hexane, etc..) are heated and allowed to flow through the plants.

The solvents when saturated with the plant essential oils are evaporated off, leav­ing certain odoriferous material behind them together with some che­mical residue.

This process is relatively cheap and favored by the cosmetic industry.

The substance generated is known as con­crete.

Concretes should be avoided in Aromatherapy as they not only contains chemical residue from the solvents, but also because the balance of constituents extracted by the solvents is different from those extracted by steam distillation.

Carbon Dioxide Extraction

This is a fairly new method of essential oil extraction, introduced at the beginning of the 1980s. It utilizes compressed carbon dioxide.

The technology calls for extremely expensive and complicated equipment (several million dollars worth), which uses carbon dioxide at very high pressures and low temperatures.

With this method, more top notes, fewer terpenes, a higher proportion of esters and larger molecules are obtained.

The resultant oil is said to be more like the essential oil in the plant. Many terpenes in a distilled oil seem to form during the distillation process, which also breaks down some of the acetates (esters) in the plant material.

Carbon dioxide (CO2) extracted essential oils are pure, stable, colorless and have no residue of CO2 left in them. They should be excellent therapeutically, although this needs to be verified for each oil on account of their different compositions.

Hydrodiffusion Or Percolation

Percolation is an even newer method of essential oil extraction than CO2 extraction.

Most of the resultant oils have an aroma nearer to the plant, better than a distilled oil.

The equipment, unlike that for CO2 extraction, is very simple and the process quicker than distillation, the plant being in contact with the steam for a much shorter time.

This process works like a coffee percolator. The steam passes through the plant material from top to bottom of the container, which has a grid to hold the plant material.

The oil and condensed steam are collected in a vessel in the same way as distillation.

The color is much richer than that of distilled oils and time and tests alone will, as with the CO2 method, reveal their true value in aromatherapy.

Maceration

This is used for plants that do not generate essential oil after harvesting.

The flowers are plunged into hot fat which penetrates into the cells of the plants and absorbs their oils.

The flowers are then removed either by centrifuge or staining and fresher flowers introduced.

This is repeated up to fifteen times and the resultant is a pomade treated like that of enfleurage.

Dissolving

To obtain an absolute from the concrete, the concrete is treated with a strong alcohol in which certain constituents dissolve. The alcohol is evaporated off completely, leaving the absolute.

Dissolving can also be used for extracting gums and resins of plants and trees such as frankincense and myrrh.

The gums and resins are immersed in alcohol in which they dissolve. The alco­hol is then evaporated off completely. What is left behind is a resinoid which, although not as good as steam distillation, can be used in Aromatherapy.

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