Table of Contents
Obtaining Natural Odorants
Before perfumes can be blended the odorants used in various perfume compositions must be obtained.
Synthetic odorants are produced through organic synthesis and then purified. Odorants from natural sources require the use of various methods in order to extract the aromatics from the raw materials.
The results of the extraction are either essential oils, absolutes, concretes or butters depending on the number of waxes in the extracted product.
Using these techniques will almost certainly distort the odour of the aromatic compounds obtained from the raw materials.
This is mainly due to the use of heat, harsh solvents or through exposure to oxygen in the extraction process which will denature the aromatic compounds which either change their odour character or renders them odourless.
Maceration/Solvent Extraction
This is the most used and economically important technique for extracting aromatics in the modern perfume industry. Raw materials are submerged in a solvent that can dissolve the desired aromatic compounds.
Maceration can last anywhere from hours to months. Fragrant compounds for woody and fibrous plant materials are often obtained in this manner as are all aromatics from animal sources.
The technique can also be used to extract odorants that are too volatile for distillation or easily denatured by heat.
Commonly used solvents for maceration/solvent extraction include ethane, hexane and dimethyl ether. The product of this process is called concrete.
Supercritical Fluid Extraction
This is a relatively new technique for extracting fragrance compounds from a raw material which often employs CO₂.
This comprises of a low heat process and a relatively non-reactive solvent is used in the extraction resulting in the fragrant compounds closely resembling the original odour of the raw material.
Ethanol Extraction
This is a type of solvent extraction used to extract fragrant compounds directly from dry raw materials. As well as the impure oily compound materials resulting from solvent extraction ethanol extraction from fresh plant materials contain large quantities of water which will also be extracted into the ethanol.
Distillation
This is a common technique for obtaining aromatic compounds from plants such as orange blossoms and roses.
The raw material is heated and the fragrant compounds are recollected through condensation of the distilled vapour.
Steam Distillation
Steam from boiling water is passed through the raw material which drives out their volatile fragrant compounds and the condensate from distillation are settled into a Florentine Flask which allows for the easy separation of the fragrant oils from the water.
The water collected from the condensate which retains some of the fragrant compounds and oils from the raw material is call hydrosol. This the most commonly used for fresh plant materials such as flowers, leaves and stems.
Dry/Destructive Distillation
The raw materials are directly heated in a still without a carrier solvent such as water. Fragrant compounds that are released from the raw material by the high heat often undergo anhydrous pyrolysis which results in the formation of fragrant compounds and thus different fragrant notes.
This method is used to obtain fragrant compounds from fossil amber and fragrant woods where an international burned or toasted odour is desired.
Fractionation
Using a fractionation column different fractions distilled from a material can be selectively excluded to modify the scent of the final product.
Although the product may be more expensive this is sometimes performed to remove unpleasant or undesirable scents of a material and affords the perfumer to have more control over their composition process.
Expression
In this process the raw material is squeezed or compressed and the essential oils are collected.
Of all raw materials only the fragrant oils from the peels of fruits in the citrus family are extracted in this manner since the oil is present in large enough quantities to make this extraction method economically feasible
Enfleurage
This is the absorption of aroma materials into solid fat or wax and then the extraction of odorous oils with ethyl alcohol.
Extraction by enfleurage was commonly used when distillation was not possible because some fragrant compounds denature through high heat. This technique is not commonly used in the modern industry due to prohibitive costs and the existence of more efficient and effective extraction methods.
Fragrant Extracts
Although fragrant extracts are known to the general public as essential oils a more specific terminology is used in the fragrance industry to describe the source, purity and technique used to obtain a particular fragrance extract.
Of these particular extracts only absolutes, essential oils and tinctures are directly used to formulate perfumes.
Absolute
This is a term for fragrant materials that are purified from a pommade or concrete by soaking them in ethanol.
By using a slightly hydrophilic compound such as ethanol, most of the fragrant compounds from the waxy source materials can be extracted without dissolving any of the fragrant less waxy molecules. Absolutes are only ever found in the form of an oily liquid.
Concrete
This is a term for fragrant materials that have been extracted from raw materials through solvent extraction using volatile hydrocarbons.
Concretes usually contain a large amount of wax due to the ease in which the solvents dissolve various hydrophobic compounds. As such concretes are usually further purified through distillation or ethanol based solvent extraction. Concretes are typically either waxy or resinous solids or thick oily liquids.
Essential Oil
These are fragrant materials that have been extracted from a source material directly through distillation or expression and obtained in the form of an oily liquid. Oils extracted through expression are sometimes called expression oils
Pommade
This is a fragrant mass of solid fat created from the enfleurage process in which odorous compounds in raw materials are absorbed into animal fats.
Pommades are found in the form of an oily and sticky solid.
Tincture
These are fragrant materials produced by directly soaking and infusing raw materials in ethanol. Tinctures are typically thin liquids.
Products from different extraction methods are known under different names even though their starting materials are the same.
For example the orange blossoms from Citrus Aurantium that have gone under solvent extraction produces orange blossom absolute but that which have been steam distilled is known as neroli oil.
