How do you know an essential oil is of good quality?
1. Let us first take a look at how, as a professional in the industry, we evaluate and compare the quality of our oils.
We do love essential oils and are selecting what we consider to be some of the best qualities out there. And deciding what quality to select is a bit like selecting wines, this is first and foremost a sensory (smell here) evaluation.
Let's start maybe by saying that one need to compare at least two qualities to state that one is better than the other. This is obvious of course and the more qualities of a particular oil you are able to smell and compare, the more knowledge you will build.
But before smelling an oil against another, it is important to make sure that you are comparing apple to apple. The questions to ask are the following:
- Are the two essential oils I am comparing pure and natural?
- Are they the same botanical species (and when applicable varietals)
- Do they have a specific chemotype* and is it the same
- What are the country/region of origin?
- How are they distilled? Water? Steam? Expression?
- Are they whole, rectified, fractionated, etc?
Only once you have this information can you truly start making some smell comparisons. This is the technical part.
But then how do we know what's better?
To answer this question, you need to slowly build your knowledge. The way to do it is usually by:
1) having discussions and smell with people/peers who have some experience to share. I was lucky to work alongside some of the best 'noses' (perfumers) in the world for many years and engage regularly in smelling sessions. So when you start, listening to comments by professionals about the character of certain oils is hugely important. And perfumers are not the only people who can share: distillers, quality control or lab technicians, passionate amateurs, aromatherapists, etc.
2) building a vocabulary to help characterise and memorise what you are smelling. This means sometimes getting into some details like 'this rose oil has a slightly peppery note with a slight artichoke like smell on top of a fruity rosy character"
3) taking notes, references of the supplier and keeping samples. Many essential oils will last years so keep them as long as you can; discard only when they start clearly getting bad.
As you are getting ready to evaluate a new oil you can then use that knowledge you have built and even pull out other/older samples of the same oil to compare.
1) It's first important to be in a calm environment, with no other strong smells so you can fully concentrate on what you are smelling.
2) When you take a first sniff, you might initially detect if something is a bit off with an oil - like when wine is corky - If that is the case, you will notice some 'boiled' or 'burnt' notes for instance, suggesting that something went wrong during the distillation, or that the oil might need to be aerated. Sometimes it is some other uncharacteristic facets/notes due to the harvesting, the quality of the botanical and where it is grown.
3) Once the obviously 'subpar' oils are eliminated you will then start making selections that can be more personal. Because keep in mind that there is no such thing as the best lavender oil in the World! Once you eliminate the 'not so great oils', and there are many, you will still find a lot of good quality out there. And we are allowed to have different taste!
Lastly, we have been talking here about quality as 'scent quality'. There are other definitions of quality depending who you ask: some will talk about the composition of an oil (its balance of natural constituents), some will talk about the purity and integrity of an oil, some about sustainability.
For us though, at the end of the day and everything else being equal, it's all about how beautifully an essential oil smells. So enjoy your journey.
*Chemotypes are often defined by the most abundant chemical produced by a particular aromatic plant, due to its specie and varietal and its terroir, ie geographic location, soil and climate.
2. So what does it take to produce a quality oil then?
Here are the key steps that influence the quality of an essential oil, from the producer perspective:
- botanical specie and varietal
- terroir, location, soil. the country of origin is not enough.
- climate that particular season
- care of the farmer for the land and the botanical. Does it need pruning, weeding, watering, etc
- timing of the harvesting: is the harvest at the right maturity, ie the time when the plant will deliver a better oil?
- selection of the plant part that is going to the distillery. If a flower, are the stems and leaves removed, if a fruit, are there pieces of wood as well?
- distillation equipment
- distillation know how and technique
- post distillation work: agitation/aeration to let the oil breathe and lose some unwanted top notes. Note that some crude oils are sometime re-'extracted' to remove an unwanted fraction for instance but this topic is a long discussion in itself so we will leave that for another blog.
And to be successful as a producer is first and foremost to understand and have a knowledge of the target quality one want to achieve. This is what will condition all the other steps.