Extraction methods in perfumery: distillation, solvents, CO₂ and expression

A fragrance material can be obtained or transformed through several processes. The choice of extraction method influences the olfactory profile, yield, stability, and composition of the resulting material. There is therefore no universal method: the process depends on the plant, the part used, the molecules sought, and the desired result.

1. Why extract a material?

A flower, leaf, root, bark, or resin contains numerous substances. Extraction seeks to transfer a portion of these compounds into a form usable in perfumery.

The result is not necessarily identical to the scent of the fresh material. Heat, water, a solvent, pressure, or time can modify what is extracted and therefore the final profile.

2. Steam distillation

Steam distillation is one of the major techniques used for aromatic materials. Steam passes through the plant material and carries off a portion of the volatile compounds. After condensation, the essential oil can be separated from the aqueous phase.

This method is particularly important for many leaves, woods, roots, seeds, and other materials containing sufficient volatile compounds compatible with the process.

It is used, in particular, to obtain essential oils from materials such as vetiver, patchouli, or certain spices.

3. Hydrodistillation

In hydrodistillation, the plant material is placed directly in water and then heated. The principle also relies on the entrainment of volatile compounds before condensation.

The distinction between hydrodistillation and steam distillation lies mainly in how the material is brought into contact with water or steam. In both cases, heat and water can influence the resulting profile.

4. Cold pressing

Expression (or cold pressing) is particularly associated with citrus peels. It allows for the recovery of an odorous fraction without applying the same principle of distillation.

Citrus essential oils are thus often obtained from the rinds. This method helps preserve a profile characteristic of the citrus fruit, but the materials obtained remain sensitive to certain phenomena of oxidation and degradation.

5. Volatile solvent extraction

For certain delicate flowers, distillation may be unsuitable or may strongly alter the scent. Extraction with volatile solvents allows for the recovery of a broader fraction of odorous compounds.

The process notably leads to a concrete, which can then be treated with alcohol to obtain an absolute. These two products are therefore not interchangeable.

This family of processes is historically important for certain flowers, including jasmine, and allows for working with very rich profiles.

6. Supercritical CO₂

Supercritical CO₂ uses carbon dioxide placed under temperature and pressure conditions that allow it to exhibit behavior between that of a gas and a liquid. It can then act as an extraction solvent.

The value of this technique lies notably in the possibility of extracting certain molecules under conditions different from those of conventional distillation. Depending on the material and the process, the profile obtained can differ significantly from an essential oil.

CO₂ is therefore not simply a "more natural version" of distillation: it is a different process, with its own parameters and results.

7. Maceration and oil extraction

Some traditions use an oily medium to transfer odorous compounds from plant materials into a carrier oil. In traditional Indian perfumery, attar processes rely notably on the distillation of aromatic materials into an oily base, often sandalwood oil.

This logic must be distinguished from industrial solvent extraction: the process, the medium, and the final product are not the same.

8. Resins, gums, and balsamic materials

Resins and gums can be used differently than flowers or leaves. Some are collected directly as plant exudates, then cleaned, sorted, dried, or processed.

Frankincense, myrrh, benzoin, labdanum, and other resinous materials illustrate the importance of harvesting and processing even before any extraction in the strict sense.

9. Distillation, extraction, and transformation: do not confuse everything

10. Why can two extracts of the same material smell different?

The process selects a portion of the constituents and can modify their proportions. The result also depends on the botanical origin, the harvest, the storage, the treatment, and the extraction parameters.

It is therefore normal that an essential oil, an absolute, a CO₂ extract, and a traditional material resulting from another process do not have exactly the same scent.

11. Extraction and Oriental perfumery

This diversity is particularly visible in Oriental perfumery. Oud can be worked in different forms; saffron, spices, flowers, and resins can also be offered as raw materials with different profiles depending on their origin and transformation.

The traditions of India and Kannauj also show that an extraction technique can become an integral part of olfactory heritage: the method is not just a means of producing a material, it contributes to its identity.

12. How to read a material sheet

To understand a material, look at least for:

• the botanical name when available;
• the part of the plant used;
• the geographical origin;
• the extraction or transformation process;
• the form of the product: essential oil, absolute, concrete, extract, resinoid, etc.;
• storage and preservation conditions;
• available traceability information.

Key points

Distillation, hydrodistillation, expression, solvents, CO₂, and traditional processes are not synonyms. Each technique selects and transforms the odorous fraction differently. To analyze a fragrance material, one must therefore always link material → part used → process → extract obtained → olfactory profile.

Reference sources

• Books and scientific publications on aromatic material extraction technologies.
• Royal Botanic Gardens, Kew — botanical data on species used in perfumery.
• Scientific references on distillation, solvent extraction, and supercritical CO₂.
• Documentation on traditional attar and deg-bhapka techniques in Kannauj.