Expression

In perfumery, raw materials can be extracted in different ways. Expression is one of the extraction processes. This technique, which is quite old, is used to extract the essence contained in the peel of citrus fruits.

Different extraction processes

Here are the different extraction processes for the raw materials used in perfumery: 

 

Raw materials on the perfumer's organ

There are a total of 1000 natural and 3000 synthetic raw materials available. Among this wide range, the perfumer usually selects 1,000 for the perfume organ (a piece of furniture that allows a professional to store and classify his vials of essential oils), among those they prefer or which will be technically indispensable for the creation of his fragrances. New materials are discovered and marketed every year, while others disappear, often due to increasingly strict legislation.

 

 

Understanding the orchestration of a perfume

Before explaining what the extraction process consists of, it is important to recall how the orchestration of a perfume is organised.

Perfumes often evoke poetry, dreams and emotions, they are above all based on advanced scientific and physical notions. Indeed, each perfume is a complex, sophisticated and delicate composition of notes chosen for their ephemeral or tenacious side.

The architecture of a perfume is visually represented in the form of an olfactory pyramid, with the top notes (the most volatile notes, felt just after the perfume has been sprayed) being on the top of the pyramid, the heart notes in the middle and the base notes in the bottom. At the first sight, it is a simple and pedagogical scheme, but in reality it is much more complex, as the different notes respond to each other, intertwine, interweave and can sublimate each other. A well-orchestrated perfume will allow you to smell the base notes as soon as they take off. 

The olfactory pyramid is used to balance the orchestration of a formula. This allows the perfumer to make the fragrance harmonious, and to ensure that its evaporation is continuous and gradual. In this way, the perfume will be able to deliver all its facets, giving it more life and interest.

 

Expression and top notes

The top notes create the first impression of the perfume. They consist of fresh, volatile and often sparkling notes. These top notes escape after the first scents of alcohol, which are even more ephemeral.

Citrus fruits are part of the top notes (see Citrus facet). They bring a smile to the perfume, open the fragrance and give it sparkle and joy. The main citrus fruits used in perfumery are bergamot, sweet orange, bitter orange (sour orange), mandarin, lime and lemon.

 

History of the expression process

The process of expression was developed in Sicily, Italy, in the 19th century, so it is quite old. It is a mechanical treatment that allows the recovery of the essential oil (or essence), located in the peel of citrus fruits (also called zest or epicarp). This treatment is only used for citrus fruits.

In the past, the expression was done manually by a process called "sponge painting". The fruit was cut in half, hollowed out of its pulp and left to rest for a few hours. This manual treatment with a stick required great dexterity.

The aim was to extract as much essential oil as possible from the small vesicles located in the peel of the citrus fruit. The sponges that absorbed the essence were then wrung out in large earthenware vases. This method still exists today, but remains very confidential.

Another ancient technique known as "spooning" consisted of scraping the peel of the citrus fruit with a spoon in order to harvest the essence.

 

Today's expression techniques 

Today, the new expression treatments are highly technical and perfected.

The fruit arrives from the plantations and remains in place for 72 hours before being treated. Then, they are washed and sorted by hand in order to remove any damaged fruit. The citrus fruits are placed in small compartments and are confronted with a mechanical scraper, called "pélatrice". This machine is mainly used to process the bergamot.

The whole fruit is then placed into this peeler: the walls of the machine take care of peeling off the zest, then prick the peel to release the essence from the glands (called oil glands). The final mixture of oil and water is then separated by the centrifuge. This process is carried out "cold" and does not require heating, which makes it possible to restore the flavours of the raw materials very accurately. Conversely, with distillation or volatile solvent treatment, the raw materials are heated.

For the oranges, for example, extraction is carried out on the entire fruit. It is pressed with the peel and juice, then the centrifuge comes into action, in order to separate the fruit juice from the essence of the peel.

Initially, these treatments were mainly practiced in Italy, but are now also practiced in Brazil and California.

 

Raw materials obtained by expression: citrus fruits

The expression process can only be used for citrus fruits. Here are some of them:

  • Bergamot: the "fine flower of the hesperides".

Bergamot, nicknamed the fine flower of the hesperides, is the most coveted citrus fruit, because it is very faceted. Bergamot comes mainly from Calabria, a region in southern Italy, where 1100 farmers cultivate the citrus fruit and produce around 110 tons of essential oil each season.

  • Other citrus fruits 

Mandarin is grown in Calabria and the rest of Italy. There are several varieties, such as green, yellow and red mandarins. The Italian lemon comes from the Palermo, Messina and Syracuse regions in Sicily.

 

Essence yields by expression

Here are some examples of the essence yields of certain citrus fruits extracted by expression: 

  • Sweet orange: 1000 fruits are needed to produce approximately 500 to 600 grams of essence.
  • Bergamot: 1500 fruits are needed to obtain one 1 kg of essential oil.
  • Lemon: 1500 fruits are necessary to produce one 1 kg of essence. 


Citrus fruits and the sun

Citrus fruits are very fragile raw materials that can only be stored for about 6 months. After the harvest, all these fruits are then processed by molecular distillation to remove photosensitizing principles such as bergapten or furocoumarin, which cause stains when exposed to the sun (see Perfume for summer).

 

Sylvaine Delacourte fragrances

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