Extracting Essential Oils
"The exquisite pleasure derived from smelling fragrant flowers would almost instinctively induce man to attempt to separate the odoriferous principle from them, so as to have the perfume when the season denies the flowers. Thus we find the alchemists of old, torturing the plants in every way their invention could devise for this end; and it is on their experiments that the whole art of perfumery has been reared."
— G.W. Septimus Piesse, The Art of Perfumery
(The complete text of this 1857 book is available to members of the Perfume Maker's Club as a free 132 page download in pdf format.)
In Part I of this series we learned how to make a simple perfume by soaking flower petals and other fragrant materials in water. But we also discovered that flower petals and other fragrant materials do not give up their scent so easily to our efforts.
One our Voyage of Discovery we learned that by applying heat to these materials, additional scent can be extracted, but that heat, while useful for extracting fragrance from more solid materials, was not as helpful for capturing a strong floral aroma.
Our conclusion was that at this point technology was needed to give us workable quantities of the essential oils that would allow us to progress to our next level of perfume creation.
Historically, by the beginning of the 19th century (1800), four technologies had been established for extracting "the odoriferous principle" from flowers and other natural materials. Among these technologies was distillation.
We have already discovered that we can extract a fragrance from natural materials with water and heat. Distillation is simply a refinement of this technique. If you have a bent for chemistry, you can set up your own home still with either kitchenware (awkward!) or some basic chemistry lab equipment (more practical).
But first let's look at what happens to our fragrant material in the distillation process.
Technologies of Essential Oil Creation: Distillation
The earliest, crude, technique for obtaining an essential oil through distillation involved placing the "odoriferous principle" (your natural materials) in an "iron, copper or glass pan," covering the materials with water, and fitting a dome shaped top to the pan. An opening at the top of the dome led to a corkscrew shaped pipe (the "condenser") which ran for a distance and terminated over a bucket, tank or jar (the "receiver").
Heat was applied to the pan holding the water soaked natural materials. As the water boiled, the fragrant oils released from their source and were drawn into the water. As the boiling water was vaporized into steam, it rose to the top of the dome and escaped into the corkscrew tubing where cooled, it liquefies and drips down into the receiving tank.
As the liquid in the receiving tank continued to cool, it separated into two layers: (1) the essential oil extracted from the natural materials, which, being lighter than water, rose to the top, and (2) the water, now scented with the aroma of the essential oil. In commercial production, the essential oil became one product, the lightly scented water, another.
While you can set up chemistry lab equipment and duplicate this process, a word of warning. This is not the ideal way to produce an essential oil. Why? Because in the technology which has just been described — and which was widely used up until the middle of the 19th century — the heat, applied directly to what a moonshiner would call the "mash," is destructive of delicate floral aroma.
Thus a refinement of this technology was developed: steam distillation. Steam distillation was developed and perfected by companies seeking a higher quality of essential oil. With additional refinements this technique continues in wide usage today.
Steam distillation of fragrant materials to produce essential oils
In the production of essential oils, heat is both our friend and our enemy. With heat we can extract the essential oil from a flower. But this same heat can destroy the beauty of the aroma of the oil we have extracted. Thus the next step in the use of heat to produce an essential oil was to separate the heat and water from the source material. This process is called steam distillation.
In steam distillation, the fragrant materials are placed on a screen above or away from the water and heat. Steam alone is passed over the fragrant materials. Again, the process extracts oils from the natural materials and passes it through the top of the dome, into the condenser to liquefy and into a receiving tank where the essential oil, once cooled, is separated from the lightly scented water.
But a refinement is added to this process. In modern equipment, the temperature and pressure of the steam can be controlled so that it is just hot enough to extract the oil from a particular material with minimum harm to the aroma.
Different natural materials can be subjected to differing temperatures of steam and pressure thus minimizing the destructive effects of the heat.
This technology has become a major industrial process for producing essential oils on a commercial scale. Many of the highest grade essential oils available today have been produced through high-tech steam distillation technology. Even with your own lab equipment, it would be extremely difficult to replicate the top level technology used to produce essential oils by steam distillation.
Heat, friend and enemy, continues to be impractical for extracting the aroma of several very delicate flowers which happen to be among those most prized for perfumery. This leads us to an extraction technique called enfleurage. But before taking up the subject of enfleurage, let's take a side trip to India and the Middle East and explore The World of Attars.