Enfleurage is one of a host of solvent extraction techniques in the perfume and aroma industries. Enfleurage was established in the 17th and 18th centuries alongside the growth of the perfume craft in the French city of Grasse. For delicate flowers such as jasmine and tuberose it was the only method of extraction, because the high temperatures of methods such as steam distillation would destroy or denature their fragrant compounds.
In cold enfleurage, a large framed glass plate called a chassis is smeared with a layer of animal fat, usually lard (from pork) or tallow (from beef), and left to set. Botanical matter, usually petals or whole flowers, is placed on the fat, and its scent diffuses into the fat over 1-3 days. The spent botanicals are replaced with fresh ones until the fat has reached the desired degree of fragrance saturation. The spent petals were removed after 24 or 48 hours, or after 72 hours for tuberose. When the process was complete, the pomade, saturated with odors, was scraped off and washed with wine spirits. Cold enfleurage was used to extract the oils of fragile flowers such as orange blossom, jasmine and tuberose.
In hot enfleurage, solid fats are heated and botanical matter is stirred into the fat. Spent botanicals are repeatedly strained out and replaced with fresh material until the fat is saturated with fragrance. This method is considered the oldest-known procedure for preserving plant fragrance substances.
The fat containing the fragrance is called enfleurage pomade. The pomade was either sold as it was or further washed or soaked in ethyl alcohol, which draws the fragrant molecules out of the fat. In making an absolute, the ethanol extract is cooled, for example to -15 °C, so that waxes solidify, and it is then cold filtered to give a liquid extract. The alcohol is then separated from the fat and waxes and allowed to evaporate, leaving the absolute of the botanical matter. The spent fat is usually made into soap, since it is still relatively fragrant. Instead of enfleurage, plant material can be extracted with nonpolar hydrocarbons such as toluene or hexane to give a concrete, which contains fats, waxes and essential oils; extracting the concrete with ethanol again gives an absolute free of waxes and fats.
Enfleurage is highly inefficient and costly. Today it has been almost completely abandoned. The method has been superseded by solvent extraction and by supercritical fluid extraction using supercritical carbon dioxide or similar compressed gases.
