Enfleurage
An odourless fat absorbs the aromatic molecules a flower gives off, at room temperature, over many days. No heat, no pressure — only time and the affinity between aromatic molecules and fat. As for solvents, it has to be stated in two stages. The absorption stage uses no solvent: the fat is a carrier, holding the aromatic part and remaining in the product. A product stopped here is called a pomade. The recovery stage does use one. To separate the aromatic part from the fat you have to wash it with alcohol and then let the alcohol evaporate — and that is a solvent in the strict sense. The product after this step is called an absolute. The solvent line coincides exactly with the line between the two product names: a pomade has used no solvent, an absolute has.
- Temperature
- Room temperature, about 20 to 25 °C
Process
A glass plate is coated with a layer of purified, odourless fat; the frame is called a chassis. Freshly picked flowers are laid on the fat, face down.
The flowers stay alive and keep giving off scent for many hours. The aromatic molecules diffuse into the fat and are held there.
After one to three days the spent flowers are picked off and replaced with a fresh batch. The process is repeated dozens of times until the fat is saturated, forming a pomade.
The pomade is washed with alcohol to separate the aromatic part from the fat, and the alcohol is then evaporated, leaving the absolute.
Effect on the smell
It keeps the smell closest to the living flower of any method here, because the flower goes on giving off scent while being absorbed — in theory it captures even molecules the flower releases only after picking.
Limitations
So labour-intensive that it is no longer commercially viable. One batch needs dozens of flower changes over several weeks, each done by hand.
A point about the compound profile, often overlooked when enfleurage is compared with solvent extraction. Fat is a lipophilic carrier, so it does not absorb every group equally: the more lipophilic a molecule, the more easily it enters, while more polar groups enter poorly.
So enfleurage absolute and solvent-extracted absolute from the same flower give two different analyses, not merely because one contains trace hexane. The difference lies in the proportions between groups of compounds, and it can be read on GC.
How to recognise a product made this way
You are almost never going to find it on the market. If a brand claims enfleurage, ask about the actual process and the number of flower changes — the answer will tell you at once whether it is the real technique or just a sales word.
History
Enfleurage developed in Grasse from the eighteenth century and dominated white-flower extraction until solvent extraction arrived at the end of the nineteenth. Today almost nobody practises it commercially; it survives mainly as a demonstration technique and in a few craft workshops.
Few people know that Vietnam has a living variant of this technique. Lotus-tea and jasmine-tea scenting use the same principle, only replacing fat with dry tea leaves — a dry, porous base that absorbs smell very well.