METHODS OF EXTRACTING ESSENTIAL OILS

Hydrodistillation

This method of distillation is the most ancient and is still used in most backward countries. In this method of extraction, the plants are fully submerged in water, till a soup is formed. This soup is then heated and the resultant steam contains the aromatic plant molecules. This method runs the risk of burning the essential oils by the still running dry or getting overheated. The resulting EO may have an offensive burnt smell. Hydrodistillation should be used for powders and on very tough materials like roots, wood, or nuts.

Distillation

This is the most commonly used method for producing majority of the true essential oils. The processes might differ but the basic principle is that steam produced by heating water carries the most volatile chemicals of the aromatic material with it. A condenser is used to chill the steam and the resultant distillate is collected. The essential oil, in most of the cases, will be found floating on top of the distilled water component (the hydrosol) and can be separated easily.

Steam Distillation

True Steam distillation involves the use of an outside source of steam. This steam is piped into the distillation unit, sometimes at high pressure. The steam passes through the aromatic material, carrying the most volatile chemicals of the aromatic material with it and exits into the condenser.

Water & steam distillation

This method is best for distilling leafy materials, but doesn't work well for tough materials like woods, roots, nuts, etc. In a water and steam distillation arrangement, the botanicals are supported in a basket kept over boiling water. This ensures that the plant material is exposed only to the rising steam vapors.

Solvent Extraction

Certain aromatics like Linden Blossom , Jasmine, etc. ,being very delicate, can not be extracted through the process of distillation. A process of solvent extraction must be used to capture their essence.

Perforated trays of blossoms are loaded onto an extracting unit and washed repeatedly with an appropriate solvent. Non-aromatic waxes, pigments, highly volatile aromatic molecules etc., which comprise the extractable matter from the plant is dissolved by the solvent. This resulting solution, which contains the solvent and dissolvable plant material, is then filtered. The filterate is then subjected to low pressure distillation and the solvent is recovered for further use. What remains is a waxy mass called the concrete containing the volatile oil.

The waxy material is removed by processing the concentrated concretes, and the dilute form of the pure essential oil is formed. To prepare the absolute from the concrete, the waxy concrete is warmed and stirred with an appropriate alcohol. During this process the concrete breaks up into minute globules. An efficient separation of the aromatic molecules and the wax takes place since the former is relatively more soluble in alcohol than wax. Although, during this process, certain amount of wax also becomes dissolved this can be removed by agitating and freezing the solution at very low temperatures resulting in the wax precipitating out. The absolute or the wax-free material is finally extracted by subjecting the purified solution to cold filtration.

This solvent extraction actually yields three usable products; the concrete, the absolutes and the floral waxes. These floral waxes can be added to candles, thickening creams and lotions to provide a floral scented alternative to beeswax.

Carbon Dioxide Extraction

Liquid CO2 resulting from subjecting CO2 to high pressure, has the properties of a very inert, safe, "liquid solvent." which can be used to extract the aromatic molecules in a process similar to solvent extraction. In this method, however, no solvent residue remains, since at normal pressure and temperature, CO2 reverts back to its gaseous form and evaporates.

Essences of some aromatics like Rose Hip Seed and Calendula that don't yield essential oils can be extracted using this method. Going by popular experience a CO2 extracted essence in comparison to a steam distilled EO, seems to have a richer, more intense scent, since more of the aromatic chemicals are released through this process.

Cold Pressing

Although many citrus oils are also produced by steam distillation, they seem to lack the vibrancy of the cold pressed oils. In this process, machines are used to score the rind of the citrus and the resulting oil is captured.

Florasols/Phytols

Dr. Peter Wilde was the first to recognize the unique properties of . "Florasol" (R134a), a benign gaseous solvent for the extraction of aromatic oils and biologically active components from plant materials, for use in the food, pharmaceutical, aromatherapy and perfume industries.

Extraction through this process occurs at or below ambient temperatures, ensuring that there is no thermal degradation of the products. A free flowing clear oil free of waxes is produced utilizing the selectivity of the solvent.