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Traditional Extraction of Essential Oils 2: Flowering

Written by Hannah Parry


Posted on December 02 2019

The term "chilling" does not exist as such in Spanish, it is the translation of the French word "enfleurage"; However, being very necessary in perfumery, we have adopted the one that heads this post so as not to have to go to the foreign lexicon.

We know that it is not always possible to obtain essential oils by distillation; their alteration or poor performance are the main causes that prevent going to the aforementioned procedure. The power of fats to absorb the perfume of flowers is well known. Well, on this property, precisely, the process of cooling is based.

In the industry, two different procedures have been followed so far: maceration , consisting of the immersion of flowers (roses, orange blossoms, etc.), in the fat melted in the water bath and separation of it once scented by pressure. In this case, the fat acts as a liquid solvent, unlike the other system, the cooling , which consists of arranging the flowers (tubosa, jasmine, etc.) on looms covered with grease by placing these looms on top of each other and in a closed space, the fat fixes the perfume of the flowers as they dry. The operation is repeated until the concentration due in perfume is reached.

There are some flowers in which the whole aroma is formed and, therefore, its extraction can be done directly, already by distillation, with water vapor, fat infusion, depletion with appropriate solvents, sulfuric ether, petroleum ether , etc;
but there are others, in which the entire perfume is not formed, but instead, it is produced during the life of the vegetable, and in this case, the fats only absorb the aroma that develops while the flower lives after of its collection.

These considerations led Jacques Passy to devise a procedure that allowed the extraction during the life of the flower and as the perfume was produced.
The solution to the problem addressed by Passy is to find an environment, different from the air, in which the vital activity of the flowers took its normal course, but at the same time absorbed the perfume by diffusion. Passy believed that the water fills such conditions and proposes to submerge the flowers in it and renew it as it becomes rich in perfume. To prolong the life of the plant for a longer time, replace the water with saline solutions, possessing the same osmotic power as the aqueous liquids that permeate the plant tissues. After treating the liquid obtained with ether, the essence is easily isolated. Passy obtained excellent results using the system described for some flowers, whose perfume had not yet been obtained, especially with the thrush (variety of lily).

The cooling made with molten fats, that is, hot, is known as maceration.
At the beginning of the 20th century they were melted in a water bath in a copper or porcelain bowl, lard and purified kidney fat, and the flowers were added to the melted and pasted dough.

Maceration was maintained between 12 and 48 hours, after which the exhausted flowers were removed and new ones were introduced, an operation that was repeated the number of times necessary to achieve a sufficient concentration.
However, it was observed that olive oil of superior quality first and purified fats (paraffin or petrolatum) then produced identical results. This procedure is preferably indicated for orange blossom, rose and acacia flowers.

Cold absorption or cooling is the most important of the procedures for the extraction of perfumes. This is applicable to all essences and the only one that can give good results in those cases in which the perfume is very delicate and could be altered by the action of heat.

With this procedure, not only optimal essences are obtained, but also exquisite ointments and delicate oils.

The well purified fat is melted on direct heat, adding for every 100 kilos of it 6 to 8 liters of rose water and 30 gr. of fine powdered benjui. A little bit of benzoin is added to the formula, because it has been found that its presence prevents fat stagnation or at least makes it very difficult. Some artisans use a special butter, easily obtained by heating the fat for brief moments with poplar buds, which give it a pleasant smell, while preventing its thickening.

The cooling takes place on looms of 1 decimeter depth, for 1.65 m. long On the bottom, which is made of glass, a layer of fat of about 7 mm is spread. of thickness; Above it are distributed flowers, petals, leaves, etc., from which the aroma should benefit. The duration of the contact varies according to the perfume, between 12 and 70 hours.

The flowers are renewed when they have already been sold out.

If the cooling instead of with fat is done with oils, the system varies slightly. They are soaked with top quality olive oil, rude cotton fabrics and spread on racks with a bottom of metallic cloth, or glass.

The flowers are spread and removed as usual; finally the fabrics are under strong pressure to extract the scented oil from them.

Currently the cooling is done with paraffin or petrolatum, because animal or vegetable fats almost always alter the perfumes obtained. In order to solve such an inconvenience, paraffin, a perfectly neutral body with the same absorbent properties as animal and vegetable fatty bodies, has been used.

Paraffin has the advantage of not altering the aromas, it is solid up to 50º 60º C and provides unalterable products under all latitudes.

The procedure is similar: the flowers are placed on the plates of a filter press, kept at 50 ° by circulation of hot water. The molten petroleum jelly is passed at a temperature of 60 °, which is achieved by heating it in a closed container and by means of a steam coil.

To separate the perfume from the fat that fixes it, it is enough to treat it with an appropriate solvent, the alcohol for example, whose liquid will dissolve the aromatic part and also a kind of wax contained in the flowers (stereosite); This is separated by strong cooling, in the form of a solid mass. In cases where the action of heat is not harmful, the essence is separated by simple distillation.

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