How to check the quality of an essential oil?

How to check the quality of an essential oil? Is it within the reach of anyone or does it require a BAC+5 in organic chemistry? From the point of view of an expert in aromatherapy or a trader, the knowledge to accumulate in order to master the quality of these products must be both specialized and vast. But from the point of view of a user of essential oils, it is quite possible to make the difference, to separate the good bottles from the mediocre ones, even the bad ones. This is the objective of this guide: to make you autonomous in the critical analysis of the quality of an essential oil.

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Why are there different qualities?

Essential oils are natural products, with powerful therapeutic virtues and in general with a high market value. The offer available on the market of essential oils is consequently very diverse in terms of quality, for 3 main reasons:

  • The first is that nature is not a factory: it is not capable of producing the same standard product twice. Each plant is a living organism whose fruit will depend on the genetics of the plant, its growing conditions, the weather, the soil that feeds it, etc. For essential oils, this natural variation in quality is increased by the fact that we are using a concentrated extract of the plant's active ingredients. It goes without saying that this concentration further accentuates the natural variability of each plant. Through nature's unique intervention, batches of essential oils with the same name are often of very different quality, even from the same plantation. Of course, this difference is strongly accentuated when the biotopes are not the same.
  • The second cause of this high diversity of qualities, is fraud. Essential oils are particularly affected by this risk of fraud: they are expensive and sometimes come from the other side of the planet, with many intermediaries. Cases of fraud are legion, and often go unnoticed until the final consumer. It can be a question of dilution with simple raw materials (water, alcohol, fat...), of mixture with a close and less expensive essential oil, of a modification of the essential oil by addition of synthetic compounds or by physical processes, etc. The imagination of fraudsters can go very far, and the impact of fraud is far from negligible on the average quality of essential oils.
  • Finally, the third and last cause is the diversity of the modes of use of essential oils. Indeed, essential oils are aimed at a very varied panel of consumers, with very different quality expectations. At the top of expectations is aromatherapy, then comes the DIY cosmetics, the use in diffusion of atmosphere, and the individual use for household products. This diversity of expectations maintains a diversity of qualities available on the market.

The subject of essential oil quality is therefore a very critical one. This is not nitpicking, but real impacting factors. The purpose of this article is to help you navigate this if you are looking for 100% natural, pure, therapeutic grade essential oils. To learn more about the intrinsic quality variations in essential oils, go here :

Why does the quality of essential oils vary so much?

Organic certification, absolutely essential

First of all, let's get the facts chemically straight. A plant containing pesticides will yield an essential oil containing pesticides. Distillation does not filter out pesticides, and they are unfortunately present in essential oils. The use of pesticides in organic agriculture is very regulated and more restricted than in conventional agriculture: the few authorized phytoprotective substances have in common that they have no intrinsic toxicity. Moreover, the organic regulation imposes to use these substances only as a last resort, when no other preventive measure could be implemented. Contrary to a conventionally grown plant, an organic plant has a low risk of containing pesticide residues.

From a physiological point of view, it should be remembered that the bioavailability of essential oils is excellent: this means that the components of essential oils are very quickly present in the tissues and the bloodstream. This is what makes their strength, and their potential toxicity. If you have pesticides in your bottle and you use that bottle for therapeutic purposes, then you will be administering pesticides (you don't know which ones) to yourself where they can act directly, without a filter. The use of non-Organic (conventional) essential oils to treat oneself should therefore be absolutely avoided, for health reasons above all.

If you are looking for therapeutic quality, we also recommend that you avoid any brand that distributes organic and conventional essential oils depending on the product. This often happens, as these brands adopt the organic label for products where the price difference is not significant (Tea Tree, Peppermint, Ravintsara, etc.), but switch to conventional essential oils as soon as the price difference is greater, for reasons of raw material cost (Italian Helichrysum, Chamomile, etc.), supply difficulties, etc. This is a weak signal for the whole brand, which is voluntarily located on a less therapeutic ground (well-being diffusion, soaps, detergents, etc.).

From the point of view of biodiversity, it is also valuable to defend the BIO channels, which are prohibited from using synthetic pesticides and fertilizers. And for good reason, pesticides have a strong impact on terrestrial fauna, herbicides are responsible for the decline of many flowers and seeds essential to many species of insects and birds and nitrogen fertilizers have negative impacts on aquatic biodiversity. In fact, on average, 30% more species and 50% more individuals are found in organic plots than in conventional plots.

Finally, from the point of view of fraud control and traceability, it is important to know that the requirements of organic certification, even if they are not sufficient, participate in a greater control of the quality of essential oils. A 100% ORGANIC brand assures you that monitoring processes are in place, and that these are regularly audited (twice a year on average). This helps to avoid a good number of fraudulent batches, which are much more numerous in conventional batches than in organic batches. For example, at the moment, almost all the batches of Gaultheria present on the market in conventional contain about 30% of synthetic methyl salicylate. In BIO, the fraud rate on this product is much lower.

To conclude: should you only use organic essential oils to treat yourself? For all the reasons mentioned above, this seems pretty obvious. Taking it a step further, one could even say that one should favor brands marketing only ORGANIC essential oils for any therapeutic use.

Is the essential oil really chemotyped?

Chemotype is a word commonly used in aromatherapy jargon, but its interpretation varies, and continues to evolve as the industry becomes more professional. Originally, this word referred to the necessary distinction that had to be made between a Thujanol Thyme, for example, and a Thymol Thyme, and this distinction therefore only concerned a few species: thymes, rosemary, lavender, etc.

Today, when we talk about a chemotyped essential oil, we are talking about an essential oil whose 3 components are known by the manufacturer and specified on the label:

  • The precise botanical definition, in Latin therefore, including genus, species, and subspecies or variety (if any). For example, for a Rosemary Verbenone: Rosmarinus officinalis L. verbenoniferum, which does not have the same properties at all as a Rosemary Cineole: Rosmarinus officinalis L. cineoliferum. In France, it has become very rare, fortunately, to find essential oils that do not make this distinction. Beware, however, of some major American brands that are as expensive as they are low quality.
  • The main molecules found in this essential oil. This is a short list containing the few main molecules of this chemotype, without specifics on expected concentrations. A Ravintsara for example, will need to mention the composition in 1,8 cineole, sabinene, alpha terpineol.
  • The origin of the plant and thus its essential oil. This is a critical piece of data that is often missing, and can have a considerable impact on the price of the essential oil. It is however essential to guarantee a chemotype, and completes the list of molecules in a clear and precise way. An essential oil of Chamomile Matricaria from Nepal, for example, will indeed contain alpha bisabolol, but only 5% instead of 35% in a Chamomile Matricaria from Hungary.

A chemotyped essential oil is therefore an essential oil defined, right down to the label, on these 3 criteria: botanical (precisely) + composition (approximately) + origin (precisely). If you aspire to benefit from therapeutic virtues via essential oils, orally or dermally, the use of chemotyped essential oils is capital, for reasons of effectiveness, but also safety. So check your bottles well, and greatly favor brands indicating the origin of the lot sold.

Are the analyses of the essential oil public?

Your essential oil is ORGANIC, it is chemotyped: this is already very good, and rather rare. If you use this essential oil to purify the air in your home with a diffuser, or for a recipe for a DIY cosmetic cream, this is good enough. If you're expecting a therapeutic use, you're almost there. All you have to do is check the brand's transparency regarding the testing they do for each batch.

Why is this important?

  • This assures you that the brand has a strong control plan. Today, you don't avoid fraud with simple hunches, or random checks. Every batch must be tested, at least to verify the composition of the essential oil and its few basic physical components (density, refractive index, etc.). For the most risky essential oils, additional tests should be planned.
  • This assures you that the choice of its chemotype is relevant or has been worked, that it is not motivated by pecuniary interests, but by precise specifications, corroborated by public analyses. The composition of essential oils is also specified in most aromatherapy books. This allows users to compare with the one put forward by the brand, and verify that it is indeed the desired chemotype. For example, an essential oil of Italian Helichrysum from the Balkans may be quite chemotyped... but this chemotype is not the right one if one wishes to benefit from the properties recognized in aromatherapy books for Italian Helichrysum.
  • And finally it encourages the brand to maintain its consistency with respect to its advertised quality. Claiming to sell the best essential oil is one thing, voluntarily publishing one's analysis, at the risk of being held accountable, is another.

What analyses are we talking about?

Within the framework given above, the following analyses should be performed and analyzed for each batch of essential oil, in order to reject those that do not meet expectations.

  • The most important of these is chromatographic analysis. This is an analysis that allows us to know precisely the composition of the essential oil: which molecules, and in what quantity? This analysis and its interpretation must be the heart of any quality approach in aromatherapy.
  • Next comes the control of organoleptic characteristics. Each essential oil has a unique color, odor and appearance, identifiable among other essential oils, even those from the same plant family. Sometimes, this control can detect failing qualities that chromatography would not have seen.
  • And finally, the analysis of some physical data such as density, refractive index and rotational power, which again allow for some lots to be ruled out.

Of course, the established control plan should not be reduced to these analyses, but in terms of systematic analyses, batch by batch, we have here a sufficient basis.

How do we check?

  • The physical and chemical specifications of the essential oil, its specifications in a way, must be public (website, data sheets, etc.).
  • A lot number must be indicated on the bottle.
  • On the brand's website, the batch analysis results must be available. It is therefore possible to compare them with the specifications put forward.

As there is no certifying body for this quality requirement, the voluntary transparency of the brand about its specifications and the tests it performs for each product is decisive in the trust you can place in it.

If we recap: to ensure the therapeutic quality of an essential oil, it is therefore first and foremost necessary that it be OCN certified, that its chemotype be specified and verified (that it be chemotyped), and last but not least that the results of its analyses be accessible.