Distilling Essential Oils - An Art and a Science?
The Methods of Extracting
Distillation appears to have been practiced throughout ancient times. Based upon the current interpretation Paolo Rovesti’s discovery of an earthenware distillation apparatus, the production or extraction of aromatic oils by means of steam distillation, has been known for 5000 years.1 During the fifth century AD, the famed writer, Zosimus of Panopolis, refers to the distilling of a divine water and panacea. Throughout the early Middle Ages and beyond, a crude form of distillation was known and was used primarily to prepare floral waters or distilled aromatic waters. These appear to have been used in perfumery, as digestive tonics, in cooking, and for trading.
What are the Methods of Extracting Essential Oils?
There are many different ways to extract essential oils and a complete listing and description is provided here. This section will mainly deal with the details and methods of steam distillation.
What is Steam Distillation?
Distilling essential oils by steam distillation can be accomplished three different ways. They are:
- Water Distillation;
- Water/Steam Distillation; and
- Straight Steam.
The Methods of Extracting
Essential Oils are Still Being Proven!
Some methods of extracting essential oils have been around for thousands of years while others are still being proven. The section will give you an understanding of the different methods!
What are the Methods of Extracting Essential Oils?
There are many different ways to extract essential oils and they are listed below:
- Enfleurage
- Expressed Oils
- Steam Distillation
- Solvent Extraction
- Fractional Distillation and Percolation
- Carbon Dioxide Extraction
- Phytonic Process
What is Enfleurage?
Enfleurage is one of the oldest methods of extracting essential oils and is rarely used these days because of its high cost. It involves placing the flower petals on a layer of glass that is first spread with a thin layer of fat called "chassis". The volatile oil diffuses into the fat, then the fat is collected and the oil is extracted from the fat using alcohol.
Once the alcohol evaporates what is left behind is called the absolute. As you can imagine, this is a very time consuming process, but it was the only way to extract delicate flowers like Jasmine for a very long time!
What is Expression of Oils?
When oils are taken from the rind of fruits they are called "expressed oils". This method is cold and does not involve any solvents or heat of any kind. Most of the citrus oils are extracted in this manner including grapefruit, lime, orange and lemon essential oils.
These are not technically considered essential oils for this reason, but they are still definitely therapeutic oils. The most important thing to consider with cold pressed oils is the source of the crop since citrus fruits are constantly sprayed with pesticides and it can be very concentrated in the oil!
What is Involved in Steam Distilling Essential Oils?
Steam distillation has been used for hundreds of years and today remains one of the most favorably methods of extracting essential oils. Technically speaking if it not extracted using steam distillation or cold expression it is not a therapeutic grade essential oil.
There are actually three different steam processes that are described further in the distilling section. But in all of the methods, steam is used to rupture the oil membranes in the plant and release the essential oil.
The steam carries the essential oil to a condenser and then as it re-liquefies the lighter essential oil floats on top. The water and oil is then separated and the water portion is referred to as the hydrosol, hydrolat, or flower or floral water. And the oil portion, of course, is the essential oil!
The essential oil distilling equipment including the condenser, separator and cooking chambers can all have an enormous impact on the quality of the oil. As well as, the distillation temperature and pressure! And even if everything appears correct, the process can still produce oils that don't meet the AFNOR Standards. So essential oil distillers must have the knowledge and expertise to know how to produce therapeutic grade essential oils.
Are you interested in learning more about steam distillation? Then click here!
What is Solvent Extraction?
Solvent extraction is a method of extracting essential oils that is dominated by the perfume industry. And technically does not produce therapeutic grade oils because chemicals such as hexane, acetone, di-methylene-chloride and others are used in the process!
Did you know that the plant material is actually immersed into the solvents to become a thick substance called "concrete"?
The oil particles are released when the concrete substance is then mixed with alcohol. Once it is separated out, the chemicals remain in the oil and the oil is used by the perfume industry. These are perfume or aromatherapy grade oils and are not therapeutic grade!
As you can see this is process requires far less time and expense because the oil is cut with solvents and can increase the oil production volume significantly.
Are these the oils that are used in bath oils and gels, candles, shampoos, toothpaste, fly spray, and air fresheners?
Yup, you got it! These are also the 98% of the oils sold in health food stores, retail outlets and aromatherapy suppliers!
What is Percolation and Fractional Distillation?
Fractional distillation separates the volatile oil in different fractions or portions at various boiling points. This is used in oil refineries for distillation of petroleum products and is not suited for therapeutic grade essential oils.
Percolation is one of the newer methods of extraction essential oils. It is similar to normal distillation but the equipment is literally upside down! It has been used successfully in France; however sometimes an emulsion is produced that can not be separated out, so until it can be further developed you will not see it on a large scale.
What is Super Critical Fluid Extraction? (Carbon Dioxide Extraction)
Super critical fluid extraction or carbon dioxide extraction is also a fairly new solvent extraction process that uses carbon dioxide at very high pressure. The carbon dioxide is injected into the tank where the plant material is contained and acts as a solvent to extract the oil.
The carbon dioxide is colorless and odorless liquid and can be completely removed which is a good thing; however, there is no research at this point to verify if there are any effects of using this procedure.
Additionally, the distilling equipment is extremely expensive. So until more is known about this process, it is advised to use only steam distilled and expressed oils!
What is the Phytonic Process?
The Phytonic process is a one of the newest methods of extracting essential oils using non-CFCs (non-chlorofluorocarbons). It is also called Florasol Extraction and the oils are referred to as phytols.
What Else is There to Know about Methods of Extracting Essential Oils?
Well, if this section spurred your interest definitely read the section on steam distillation. I will give you some examples of ideal pressures and temperatures for distilling several oils, and tell you other ways that distillers adulterate their oils! So check it out!
I hope this section on methods of extracting essential oils, gave you an understanding on why using therapeutic grade essential oils are so important.
The perfume grade oils still contain a portion of the solvent and are only for fragrance so please do be careful.
How Are Essential Oils Extracted?
Essential oils can be extracted via two key methods: Distillation (includes hydrodistillation) and Expression.
Absolutes, other the other hand, can be extracted via Solvent extraction or Enfleurage, although enfleurage is rarely performed in the modern day.
Another type of aromatic product available on the market are CO2 extracts, referred to simply as that, CO2 extracts. They differ in chemistry from their related distilled essential oils but are becoming increasing available on the market.
The Practice of Distillation
Distillation appears to have been practiced throughout ancient times. Based upon the current interpretation Paolo Rovesti’s discovery of an earthenware distillation apparatus, the production or extraction of aromatic oils by means of steam distillation, has been known for 5000 years.1 During the fifth century AD, the famed writer, Zosimus of Panopolis, refers to the distilling of a divine water and panacea. Throughout the early Middle Ages and beyond, a crude form of distillation was known and was used primarily to prepare floral waters or distilled aromatic waters. These appear to have been used in perfumery, as digestive tonics, in cooking, and for trading.
Although an extensive trade of odoriferous material has been shown to have occurred in the ancient Orient and ancient Greece and Rome, the oils used were not essential oils per se, “rather they were obtained by placing flowers, roots, and other plant material into a fatty oil of best quality, submitting the glass bottles containing these mixtures to the warming influence of the sun and finally separating odoriferous oil from the solid constituents”.2
