Absolute (fragrance)

Similar to essential oils, absolutes are concentrated, highly-aromatic, oily mixtures extracted from plants. Whereas essential oils can typically be produced through steam distillation, absolutes require the use of solvent extraction techniques or more traditionally, through enfleurage.

Production

First, an organic solvent, such as hexane, is added to the plant material to help extract the hydrophobic compounds. This solution is filtered and concentrated by distillation to produce a waxy mass called concrete. The lower molecular weight, fragrant compounds are extracted from the concrete into ethanol. When the ethanol evaporates, an oil—the absolute—is left behind.

Character and use

Absolutes are usually more concentrated than essential oils, as well the efficiency and low temperature of the extraction process helps prevent damage to the fragrant compounds. With a good knowledge of the solvent they are using, extractors can produce absolutes with aromas closer to the original plant product than is possible with essential oils produced through distillation. Examples of this are rose otto (steam distilled rose oil) and neroli (steam distilled oil from the blossom of the bitter orange tree) compared to rose absolute and orange blossom absolute, respectively. Some botanicals also are too delicate to be steam distilled and can yield their aroma only through other methods, such as solvent extraction or lipid absorption. Examples of this are jasmine, tuberose, and mimosa.

Due to the the trace amount of solvents in the absolutes due to its production method, its use in aromatherapy is limited. The solvent traces are considered undesirable since it is believe that they could cause allergies and affect the immune system. In perfumery, absolutes are used extensively since they smell fresher, brighter, and jam-like, since the compounds in the absolute do not undergo high temperature processes. Although, the solvent traces produce off notes in the final product, this problem is not present is even decent quality absolute.

References

* [http://www.wsu.edu/~gmhyde/433_web_pages/433Oil-web-pages/Processing/Process-Edible%26Essence_Oil.html Oil Processing]