The Extraction of Essential Oils by Distillation and Expression

Posted on: August 1st, 2009 by
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Photo of a Simple Homemade Still

For anyone who studies essential oils, distillation is probably the most familiar method of extracting essential oils from plant material; however, not all essential oils can be steam distilled. Most citrus oils, for example, are expressed. So what does ‘distilled’ and ‘expressed’ mean? And why are there different methods of extracting essential oils?

Essential oils can be extracted in the following ways:

- Distillation – the most common method of extracting essential oils and a method which has been used for centuries essentially. Plant matter which is steam distilled is in placed in a still, heated and the essential oils (the ‘aroma’ molecules of the plant) evaporate into the steam. The molecules are then carried along a pipe and when they start to cool (as the pipe passes through a cold water vat) the molecules form into liquid – the essential oils. The essential oils can be separated from the water, as the essential molecules either “sink or float’ on the water.

Distillation is used to extract essential oils from the sacs stored in the leaves, roots, seeds and flowers of plants. Aromatherapy and Botany explains more of the storage of essential oils by plants. Some plants have no difficulty producing a large quantity of essential oil in one batch, others are extremely difficult to extract from with minute quantities of essential oil produced in a single batch.

- Expression – citrus fruits are usually expressed to extract essential oils. Essential oils are located in the rind of the fruit and need to be ‘squeezed’ out – a bit like when you peel the orange and the juice is ‘squeezed’ out of the fruit, except it is the rind which is expressed in the case of the majority of the citrus essential oils. The problem with expressing pure essential oils from citrus oils is that, in today’s world, many fruit trees are chemically sprayed, ‘contaminating’ the rind of many citrus fruits. For this reason, many aromatherapists prefer to use organic or naturally grown fruits for essential oils (although these terms can be ‘open to interpretation’ sometimes too!)

Newer methods of extracting essential oils include Carbon Dioxide Extraction (CO 2 essential oils) and Perculation which is coming up next…

Do you have any comments to add on my post on the extraction of essential oils? Add you comments below if you do!

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When is an Essential Oil not an Essential Oil?

Posted on: August 1st, 2009 by
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…an interesting question which expands on essential oil, fragrance oil or hydrosol last month. Plants are capable of producing many things from their ‘material’ – aside from essential oils, plant material can be eventually made into concretes, absolutes, resinoids and oleoresins, depending on the plant and depending on the material and extraction process. However, aside from essential oils, none of these other substances are completely ‘natural’, as they involve some sort of chemical processing through solvent extraction.
Concretes and absolutes are often used in the perfumery world as they maintain the fragrance that perfumers require – but they do not possess the therapeutic properties of essential oils for aromatherapy use.
To learn more read When is an essential oil not an essential oil? And methods of distillation and extraction of essential oils will be discussed in my next blog post…

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Medieval 'Aromatherapy' Herbals

Posted on: July 27th, 2009 by
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Herbs and plants were in use in Medieval Europe, despite the Witchcraft Acts and the often misunderstood powers of herbs and plants. Two English herbalists who contributed to the popularity of herbs and plants for medicinal purposes were John Gerard and Nicholas Culpeper. Nicholas Culpeper even mentions the use of ‘essential oils’ in his famous Culpeper’s Herbal; although they were not known as essential oils in the Medieval period, they were essentially similar to the essential oils we use today in modern day aromatherapy.
Read The Use of Medicinal Medieval Herbs to learn more…

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When Not To Use An Essential Oil

Posted on: July 25th, 2009 by
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Essential oils have different safety ‘standards’ in different countries; as I’ve mentioned previously, essential oils in France are dispensed through a pharmacist. In the UK and in the USA, this is not the case. Anyone can walk into a store, or order online, any essential oil regardless of their knowledge about essential oils.
Essential oils, if used correctly, are relatively safe to use – those three words, ‘if used correctly’ are what makes the difference. Before qualifying as an aromatherapist and having no knowledge of aromatherapy or what essential oils actually were, I did not realise the power held in one essential oil bottle. Since qualifying as an aromatherapist, I am asked all sorts of questions about the use of essential oils which makes me question whether essential oils should be on restricted sale! After all, ‘knowledge is power’, and the lack of knowledge about essential oils could make a huge difference to someone’s reactions to a particular essential oil.
I discussed the safety of essential oils in a previous blog post but thought it prudent to mention some of the ‘risk’ factors (or contra-indicators) on when not to use an essential oil. Essential oils are made up of different chemical components and therefore the chemical make-up of an essential oil can determine the ‘risk factor’ of a particular oil. Some essential oils are toxic, sensitizing and an irritant. Some other potential risks of essential oils, and therefore ‘contra-indicators’, include:
- risk to pregnant women
- risk to children and babies
-risk to those with liver problems
-risk to those with kidney problems
-risk if not used in moderation
- risk if used in sunlight
- risk of skin irritation.
Not all essential oils carry these risks, it is dependent on the chemical make-up of the essential oils; some essential oil ‘families’ do share common characteristics and therefore similar risk factors. For example, the majority of citrus essential oils are photo toxic, and the high menthone content of most mint oils is a huge risk factor for young children and babies; however, there are often exceptions to the rule (and between different botanical species), making it wise to have some knowledge of essential oils before using them.
For those with little or no knowledge of essential oils, it is important to note that essential oils should normally be administered through a carrier oil; only few essential oils should be used neat, and then only with care and knowledge. There are other methods of essential oil administeration, oral and vaginal among them, but these practices are studied at advanced level.
As I continue to learn about essential oils and their uses, I really do believe that education about essential oils is vital in their correct use. I don’t think it is necessary to be ‘medically qualified’ to administer essential oils but I do believe that having some knowledge about essential oils before using them is important. If you want to know more about a particular essential oil, click on any of the essential oil profiles on the left side of this blog to get started – and take note of any ‘risk’ factors! I would like to finish by saying that essential oils can be used in most cases relatively safely – ‘if used correctly’…

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Vetiver Essential Oil Profile

Posted on: July 24th, 2009 by
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Vetiver Essential Oil
Vetiver Essential Oil

Vetiver Essential Oil

 Another of the scented grasses which produces an essential oil is vetiver – not as well known as citronella or lemongrass , vetiver is a popular plant used in ancient perfumes of India.

It is also extremely useful for problematic skin and is a gentle, non-toxic, non-sensisitizing and non-irritating essential oil due to its high chemical content of alcohols.

Learn more about vetiver essential oil by reading my latest essential oil profile vetiver

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Quality Testing Essential Oils

Posted on: July 22nd, 2009 by
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Essential oils undergo a number of quality tests to test for their purity; as discussed in the previous blog post on essential oil suppliers, it difficult to know if an essential oil is pure. Many ‘pure’ essential oils are, in fact, ‘fragrance oils’. However, quality testing essential oils with such tests as the GC-MS and GLC means that some ‘pure’ essential oils will not ‘pass the test’. Some essential oil suppliers will provide you with the GC-MS test reports if you ask.

Quality testing essential oils is a scientific and complex process but I have tried to explain, in simple terms, the process of quality testing essential oils in my latest article Essential Oil Quality Testing

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