Extraction Methods - perfumery/aromatherapy ingredients
It’s time to talk science. Aromatic compounds. Otherwise known as the RAW MATERIALS.
Both of these terms are important to know as they are used interchangeably. Raw materials are not soluble in water, but they are fully dispersible in alcohol and carrier oils such as jojoba.
There are four different types: essential oils, absolutes, natural isolates and synthetic molecules.
But what are the differences between them?
Both essential oils and absolutes are naturally derived from the aromatic part of the plant and are processed to be a pure aroma substance (if you don’t know what an absolute is keep reading!)
Did you know…? Of the tens of thousands of plant species found on earth, only 300-500 are used in perfumery or aromatherapy. The other thousands are either too difficult to extract or do not have an aroma to extract.
Let’s dive into the extraction process for these naturals, and then return to the other raw materials. The extraction process is the method that we use to take the oil from the aromatic part of the plant.
There are five ways to do this, each with its own purpose.
1. Steam distillation
The most common method. The harvested flowers or plant parts are placed in a large industrial vat over steam. As the steam goes through the flowers, it collects molecules of essential oils. It then travels through an enclosed pipe to another tank where it collects. Since water and oil do not mix, it is easy to take the oil with a tap and drain the water from the bottom.
This ‘floral water’ is a by-product of the distillation process and is repurposed as a hydrosol that can be used as a face mist or to consume when refined to food grade. Rosewater is an example of this, and lavender water is a safe, natural way to soothe an infant as essential oils are too strong.
The mulch that is left over from the process is used by farmers as a compost for the next crop, so absolutely nothing goes to waste.
Watch the video about the world's best Ylang-Ylang and the new distillation method designed by my friend!
2. Expression
This method is not to be confused with cold pressing which is used for oils like olive, grape seed and such. Citrus fruit oils like bergamot, lime and sweet orange are made using expression. First the peels are pressed with thousands of tiny needles to the point that the oil is expressed. Then, the oil is separated from the water by centrifuge or further pressure.
Here’s an interesting fact: Rose and most other natural oils are not really ‘oils’, they are aromatic isolates; we call them oils, because they are not soluble in water. Citrus oils however are actually oils.
3. Solvent extraction
This method is very practical for delicate flowers such as jasmine, narcissus and frangipani. This extraction is used rather than steam distillation because either the heat would destroy the fragrance, or the flower does not give up her scent so easily. Like all elegant, classy ladies!
Sometimes this method is used in addition to steam distillation. For roses and lavender for example, it gives a different aroma profile than the distilled oil, so it’s possible to have two scent profiles from the same flower. This adds a more complex, rounder accord to your perfume.
For this method, the plant is dissolved in a solvent like hexane, which pulls the oils from the plant. The oils, waxes and fats are washed with warm alcohol, which is removed by a vacuum afterwards, leaving us with a pure aromatic oil.
Absolutes are generally less expensive than their distilled compatriots because less material is required.
4. Enfleurage
This is an old-fashioned technique that is rarely used nowadays. This traditional method was pioneered in 17th century France. It was used for certain flowers that do not give up their scent easily, such as lilies or tuberose. The method works by soaking the petals in animal fat until the fat is completely saturated with the fragrance. The fat is then washed with alcohol to capture the perfume, and the alcohol evaporates to leave the fragrance compound. Fresh flowers are replaced in the fat over and over again until the fat is ‘full of fragrance’, making this is a very labour intensive method and the reason it is rarely used any more.
Robertet is the only large manufacturer that I know of that still uses this method today for the precious Tuberose flower.
Fun fact: Did you know that Tuberose is related to the humble daffodil?
5. Carbon dioxide extraction
Aka Co2 extraction. This process uses pressurized CO2 to pull the desired phytochemicals from the plant. At certain temperatures, the carbon dioxide acts like a solvent, but does not have the associated dangers. With this method, the CO2 quickly and completely evaporates without requiring heat. The final essential oil has an scent that is closer to the plant’s living aroma than with steam-distilled oils, but these are oils are more costly.
In fact most of these oils are pretty expensive. But why?
It’s because a huge quantity of source plants and flowers are needed to produce even a small quantity of oil.
For example, to make one kilogram of Neroli oil, you need 1000 kilograms of flowers, and to make one kilogram of Rose oil, you need roughly 700 kg of flowers.
Time to return to our raw materials. All of the above-mentioned processes render us with essential oils or absolutes. But remember, there are four kinds of raw materials: essential oils, absolutes, natural isolates and synthetic molecules.
You will hear the word absolute quite often in perfumery. The difference between absolutes and essential oils is the process of getting the oil. Absolutes are always obtained through solvent extraction or enfleurage.
It is also important to know about natural isolates. If you are extracting a single molecule, it is a natural isolate.
If you are extracting an entire compound, it is an essential oil. Natural isolates are more powerful and therefore costlier, but the benefit is that they are more stable. Take a rose, for example. The entire compound (aka, the “smell”) consists of three natural isolates: 2-phenylethanol, geraniol and citronellol.
Synthetic molecules are another perfume compound found in aromatherapy. They are entirely man-made. Typical synthetics include chocolate, caramel, leather, gooseberry, and so on.
Top tip: Want to give your sweetheart three dozen roses for Valentine’s day but can’t make it to the florists? Substitute the fresh roses with a single drop of Rose essential oil... Because that’s how many roses it takes to make just one drop!
Think of how many details we have learned within that one tip. A rose has a compound smell made up of three different natural isolates. The way to get the rose essential oil is through a variety of extraction techniques, in this case steam distillation or solvent extraction. The only thing that this oil can mix with are carrier oils, never water.
ENROL ONTO THE FREE ESSENTIAL OIL MASTERCLASS TO LEARN MORE!
