Some years ago we had a message from a customer to say that a bottle of lemon thyme oil that we had sent her had only four months before its sell-by date, and she did not feel that she would use it all within this period.
We respectfully pointed out that it was a ‘sell-by’ date not a ‘use-by’ date, but she still felt uncomfortable and asked if she could return the oil. So of course we agreed that she could, and she sent it back, unopened.
However this left me with an unsatisfactory feeling because I didn’t want her to feel that we had sent her a substandard product. So I decanted a couple of ml of the oil, put it in a little phial and sent it back to her with our compliments and a hand-written note to say that this was a sample of the oil that she had returned, and that I hoped she would enjoy using it.
In retrospect I’m not exactly sure what I was hoping to achieve by this. I certainly didn’t get a reply from her to say, ‘Oh gosh, how silly of me! It’s such a beautiful oil, and now I really wish I hadn’t sent it back’. In fact we never heard from her again. But the half empty bottle stayed on my desk for a few months; I would sniff it quite regularly, and I came to really appreciate the soft clean liveliness of its ‘lemon sherbet’ aroma.
A few months later we booked one of those very early morning cheap flights (do you remember those days when we used to go on aeroplanes?), and as we were walking out of the door at 4am, on impulse I decided to pick up the lemon thyme and take it with me.
As it turned out, a day after we arrived at our Mediterranean destination one of our party developed quite a bad sore throat and head cold, and you can probably guess the rest of the story: a couple of steam inhalations with the lemon thyme dealt with it very effectively.
The Lemon Thyme Part of the Story
So this is partly a story about lemon thyme. It is a beautiful oil which definitely embodies the anti-infectious theme of thyme, but offers a softer and gentler experience than some of the ‘fiercer’ chemotypes of thyme. (Thyme thymol, for example, may contain 35-55% thymol, which is a phenol. Phenols are some of the most powerful anti-infectious agents in essential oils, but are to be used with caution as they can irritate the skin. Lemon Thyme contains 7%.)
The Sell-By Date Part of the Story
But I wanted to use the story also to mention something about sell-by dates. Customers are quite rightly concerned to make sure that the essential oils they receive from us are fresh. The reason for this is that essential oils contain components which will oxidise (i.e. they react with the oxygen in the air) over time, and change into different compounds with distinctly different effects, some of which can cause hazardous reactions such as skin irritation.
Oxidation is accelerated by warmth, by direct sunlight, and by long exposure to oxygen, which is why it is important to replace the caps when not in use and to store the oils properly. (And, from a freshness point of view, it’s better to have two 5ml bottles than one 10ml one).
The essential oil compounds most prone to oxidation are called terpenes and they are found particularly in citrus oils and evergreens. Therefore these are the oils that you need to be particularly careful about.
However there are some oils which contain components that oxidise very slowly. They tend to be the less volatile oils such as vetiver, patchouli, and sandalwood. These oils may last for many years and may actually improve with age, although the longest sell-by date allowed is three years. So please don’t feel you necessarily have to discard any of these oils beyond a certain date (although I am aware that if you work in a clinical or professional environment there will be legal reasons that you should be very conservative). Best is to understand a bit about the chemistry of the oils, and be guided by your nose.
Lemon Thyme Essential Oil Summary
Botanical name: Thymus citriodorus
Part of plant: Blossom/plant
Extraction: Steam distilled
Main biochemical compounds: geraniol (37%), geranial (10%), neral (9%), nerol (9%), beta-caryophyllene (7%), and thymol (6%)
Oil characteristics: No noticeable colour, lemony aroma
Safety considerations: Avoid during pregnancy and with babies and small children