Raw Materials From Tincture To Supercritical Extraction — Methods Of Natural Aroma Extraction

From Tincture To Supercritical Extraction — Methods Of Natural Aroma Extraction

11/09/16 13:25:47 (9 comments)

by: Matvey Yudov

Concretes, isolates, hydrosols, resinoids, tinctures and the fashionable CO2, it is easy to get lost among the numerous specifications of aromatic products extracted from natural raw materials. Although, if we look closer at the methods of their extraction, we could divide them into two big categories. Ok, to be more precise: two big ones and one small. Let's start with the latter.

 



I. EXPRESSION
 

A blend of volatile aromatic materials extracted from a plant is defined as essential oil. The amount of essential oils present in different plants varies tremendously: from thousandths of a percent to almost 20%, like, for example, in clove buds. If there is high amount of essential oil in a plant, it is possible to collect it directly by squeezing or pressing, and that is called Expression.

Practically, expression could only be applied to the peels of citrus fruits in order to harvest the aromatic oil. You can express essential oil from bergamot, orange, lemon, grapefruit, mandarin and some others.
 


Perhaps it is the most direct and the easiest of all methods. Cold pressed citrus essential oils retain the natural fragrance of the fruit from which they were extracted. Modern methods allow to express essential oils in the inert atmosphere, i.e. with little, or no oxygen around, using nitrogen or argon to minimize their oxidation.

Cold pressed citrus essential oils might contain up to 4% of non-volatile components. These very delicate substances are to be kept at a cold temperature (refrigerated).



II. DISTILLATION


In order to smell, all substances have to be light, volatile compounds with a molecular structure. The fact that aromatic substances evaporate more easily when heated, people have known for a very long time. More than twelve thousand years ago, ancient people intentionally put resinous logs into the fire to produce an aromatic smoke.
 


Two thousand years ago ancient alchemists found out that when heated, aromatic substances evaporate and if you subsequently set them against a cold object, they would condensate on its surface. Alchemists had special vessels with long bent necks, retorts, at their disposal, and they condensated the first prototypes of essential oils in them.

Somewhere in the 9th century, Arabian alchemists improved this method by adding a cooling circuit. In this construction, called alembic, they collected the distilled aromatic vapor. This method of extraction is called distillation. In the 21st century, we continue to use the very same method that was invented by Arabs in the Middle Ages.

Alembic

The simplest way of distillation is to put plants or their aromatic parts into a pot filled with water and heat it up to evaporate the volatile aromatic substances from plants along with the water, and then condensate them in the fridge. Volatile substances are usually hydrophobic and lighter than water, so they appear as a layer of oil which can be easily separated and collected from the surface of the water. After collection, the water itself still contains a small amount of aromatic substances, which is called herbal distillate (floral water, hydrosols, hydrolates, herbal waters, essential waters). Herbal distillates are often used in cosmetics.
 

Rose Water


There is a variation of distillation called steam distillation. In this case a steam generator is used: in a separate vessel boiling water transforms into steam which under pressure is passed through an aromatic material in a different chamber of the machine. Steam saturated with aromatic substances is then cooled and the essential oil separated. 

It is important to say that heating is a quite destructive procedure; several chemical reactions happen due to the high temperature and the essential oil never smells as the original raw material. More over, almost any essential oil contains substances which do not exist in nature, in other words artificial. For example, you can distil citruses instead of expressing them, and collect their essential oil, but "you would never get a real orange, only its marmelade," as my fellow perfumer once said.
 



III. SOLVENT EXTRACTION
 

Using different solvents, you can obtain a wide variety of aromatic products. The simplest would be tincture.
 

Home-made tincture


Tinctures are usually prepared at home: jars with raw materials are filled up with a solvent (ethanol in most cases), and left for the raw material to release its aromatic compounds. The obtained solution can be used in perfume making. Tictures can even be prepared of animal sourced materials, like ambergris, musk or castoreum.
 

tinctures


If raw materials (bark, leaves, roots, flowers or seeds) are extracted by any non-polar solvent (hexane, petroleum ether, benzene or toluene), and the solvent is then removed from the solution at a low temperature, the obtained product is called concrete. Concrete contains many heavy, non-smelling substances (waxes, paraffins, fatty acids and their ethers) but nevertheless their fragrance is deep and rich. Some concretes can be very close to the original plant aroma.
 

Benzoin Resinoid


Aromatic materials obtained by a solvent from resins or gums (a vegetal material that does not contain fiber), are called resinoids (literally "resembling resin"). They are usually tenacious semisolid substances. Sometimes they are extracted by heated ethanol (for instance benzoin or oakmoss resinoid).

An Absolute is a technically more complex product. In order to obtain it, a concrete (extracted by a non-polar solvent) udergoes a second extraction by ethanol. The ethanol extract is cooled and left for the roughage to settle, which is called flower wax. When the flower wax, and then the ethanol are removed, you get a substance of highly concentrated aromatic material, which is called absolute.
 

Tuberose Wax


Extraction of aromatic molecules can be done with semisolid solvents, for example purified animal fat. A method of extraction by a fat heated up to 50-70°С (122-158°F) is called maceration (what we usually and mistakenly call maceration is maturation, editor's note). The fatty paste saturated with aromatic substances, or pommade, undergoes a procedure similar to the absolute extracting by ethanol.
 

Enfleurage of golden gardenias, photo by Anya McCoy of Anya's Garden Perfumes

There is also a method of maceration defined as enfleurage. It is rarely used because it elaborate and expensive. In the process of enfleurage, flower petals are placed in rows on the surface of a purified animal fat, and replaced with fresh ones until the fat is fully saturated with aromatic substances. The aromatic pommade is then extracted as it is described above. The final product of maceration or enfleurage is also called absolute.

One of the most advanced methods of extraction, which was invented in the 70s, is called supercritical extraction. It employs supercritical CO2 as the extraction solvent (SCF, or supercritical fluid). In physics (in thermodynamics, to be precise), a critical temperature is the temperature above which gas can not condense under any pressure.
 

Phase Diagram


Supercritical fluid is used at a temperature and pressure above its critical point, where the boundaries of liquid and gas phases have vanished. The obtained substance has both liquid and gas properties at the same time. The density of SCF is close to the same of liquid, but lacks viscosity, which makes SCF a perfect solvent. CO2 is the most commonly used supercritical fluid, because it is cheap and environmentally safe, with а good solubility and a low critical temperature of 31.3 °С/ 88.3 F (its critical pressure is also quite low – 7.36 МPa).
 

SFE


The product of supercritical CO2 extraction is called SFE (supercritical fluid extract). CO2-extracts have a very realistic smell of the natural raw material, and this method is one of the least destructive methods of extraction. On the other hand, some find CO2-extracts lacking the personality and intensity of powerful absolutes, concretes and essential oils.
 



SHORTLY about FRACTIONATION

Sometimes natural essential oils can't be used due to a high content of its unpleasant smelling components. As a classic example we could name lavender: some of its essential oils have a high percentage of camphor whose sharp medicinal aspect is not always wanted in a perfume composition. In this case, aromatic materials can be fractioned to exclude undesirable elements or, on the contrary, to isolate the most interesting fraction for the perfumer. Using fractioning, you can get a very narrow fraction of only one substance.
 


In the middle of the 20st century, cinnamon aldehydeAnethole, Borneol, and Methyl salicylate were isolated for the first time by fractioning. These individual compounds, isolated from natural materials, are called isolates.
 

MD


As I said, modern tools allow us to isolate very narrow fractions containing only one substance. Perfumers can use these materials with improved olfactory profiles; Frederic Malle compared this method with the work of an audio engineer at the mixing console, balancing the sound by adding and removing individual properties and effects. The technique of isolating a product with a certain smell is called molecular distillation or MD. Products of molecular distillation have exceptional perfume qualities, and give the perfumer a better control over his or her creation.

 

Mat Yudov

Mat Yudov is a chemist, perfumer, and musician. Mat is also a researcher and specialist in the chemistry of aromatic materials. He graduated from Moscow State University "Lomonosov" in 1999. He writes for the popular perfume blog leopoldray.blogspot.com (in Russian).



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kapted
kapted

Thank you, Mr Yudov. I enjoy the more technical aspects behind fragrance making. But strangely, this deeper knowledge does not take away from the romance of fragrance, as Ms Gypsy mentioned.

Jan
16
2017
gypsy parfumista
gypsy parfumista

I remember many of these terms from my time (2 years) apprenticing a Master Herbalist while at University in the late eighties/early nineties. We used tincturing a lot, maceration for some things and distilled many things. Chemistry has come a long way since then and it is great to read about new processes but to also know that the same science is at use now as in the Middle Ages, used by Arabian alchemists and perfumers!

PAN by Anya's Garden is indeed awesome. No other scent I have smelled (and I used to milk goats on a farm as a teenager and am VERY familiar with the scent of a rutting he-goat) reeks quite so beautifully animalic or reminds me of a Satyr/Faun or the god Pan.

Thanks for the interesting read, Mat. I have a very active mind and am dual dominant. I love the science behind things almost as much as the fantasy and inspiration.

Smell swell & be well...
GP

Jan
15
2017
AnyaMcCoy
AnyaMcCoy

Thanks for mentioning my pioneering use of goat hair tincture in my Pan perfume, Elena. It is a tribute to the God Pan as depicted in Jitterbug Perfume. In 2006, I was the first perfumer to use goat hair tincture. There are two types of goat hair tincture, and they're full of warm luscious pheromones. I have also been tincturing, distilling and enfleuraging rare aromatics from my garden for many years. In fact, that is a photo of my Vietnamese gardenias in various stages of enfleurage that is used in this article.

Jan
15
2017
StellaDiverFlynn
StellaDiverFlynn

Fascinating read as always! :D

Nov
10
2016
jeca
jeca

@nexangelus, I haven't smell this particular by Slumberhouse, but I know that Anya McCoy did goat's hair tincture for her Pan (Anya`s Garden) perfume.

Nov
10
2016
nexangelus
nexangelus

Thanks for this informative article Mat, love your stuff! I especially enjoyed the last two sections, on the CO2 extraction and the fractionation. So much to learn about perfume still.

Also I have been thinking of the goat's hair tincture in a Slumberhouse perfume lately. Is this not the same as labdanum (or where we see the note mentioned), as this is where it originates? I am assuming it can be an animalic scent if so, or is this a purely musk dominated "note"? Just some useless pondering, so apologies if it sounds confused/confusing. No I have not smelled New Sibet, yet.

Nov
10
2016
Jyrhara
Jyrhara

Every time I read about maceration it makes me think about the novel Perfume by Patrick Suskind :-)

Nov
10
2016
Itchy&Scratchy
Itchy&Scratchy

Love chemistry, so i always enjoy reading your articles!

Nov
09
2016
chayaruchama
chayaruchama

I so appreciate all your articles, Mat.

Nov
09
2016

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