September 2, 2011
Storing Your Essential Oils: Best Practices and "Shelf Lives"
We're often asked what the "shelf life" of our oils are, or of a particular oil, as well as how best to store essential oils for longevity.
The shelf life of essential oils is a complicated question. First because each oil has a different shelf life, and much of that has to do with how the oils are stored. Some companies claim their oils do not have a shelf life, and others (like Ananda) try to be more truthful, noting that there is such a thing, even with the highest grade oils available. But answering the question very specifically is tricky, so we'll do our best to explain it all.
What Does "Shelf Life" Mean for Essential Oils?
First, what does "shelf life" mean for essential oils? The truth is they don't go "bad" as a carrier oil could (which we'll get to in a bit). They can, over time, loose a sense of freshness, and could smell "flat" or less lively. But this doesn't necessarily mean they've lost their therapeutic value.
For example, the oils which can "go flat" fastest, if not properly cared for, are the cold-pressed citrus oils: Grapefruit, Lemon, Lime, Orange, Bergamot and Mandarin. This is because they're pressed directly from the fruit, without ever being heated -- so they're in the most natural state of all essential oils. These oils are considered to have a shelf life of anywhere from 6 months to a year, yet this only means they loose some of the freshness in their aroma, not that they "go bad" as the term is commonly understood.
A couple specific oils have been shown to cause skin irritation in a small amount of the population if they've oxidized, perhaps over more than a year, again if not properly stored. Scientific examination has shown this can happen with Tea Tree and Lavender, though thus far these are the only ones known to do this. (The study discussed oils that are an ingredient in a cream or other compound, where you can imagine the life of the oil: shipping from the distiller, to the manufacturer, to the store -- and at each point the oil could sit for some time). Compare these to Helichrysum for example, which doesn't necessarily have a shelf life -- it's aroma improves over the first year, and it doesn't oxidize in a way that causes irritation of any sort.
As you can see, "shelf life" means different things for different oils. For most oils, it really comes down to their aromas being as fine, bright and potent as they were when they were fresh. Looking at it this way, the cold-pressed citrus oil have the shortest shelf life, then some of the floral oils (though not really Rose or Jasmine), herbal, and conifer needle oils. Then we get to the woods and resins: Cedarwood, Frankincense, Myrrh -- these can age quite nicely. And some oils are more highly valued the older they get: Sandalwood and Patchouli are the most renown of this group.
Storage Conditions and Shelf Life
Given all that, the storage conditions of your essential oils makes a huge difference in how long they'll stay fresh (when we're talking about oils that don't necessarily improve with age). Grapefruit, kept in a tightly capped bottle, with as little "air space" as possible, in a dark cabinet, refrigerator, can be kept for at least two years (perhaps longer) without any change in the aroma. Even if not kept "cold", but still in a dark cool cabinet, it's likely there would be no detectable change even for a year.
So essentially, if you're buying oils you plan on using up within a year, there's really no concern about shelf life at all, should you store your oils properly. And for all oils other than the cold-pressed citrus, this extends to two years or more.
The factors which age an oil are heat, light, and oxygen. Hence the ideal condition being in a cool, dark place, capped tightly. And should you decide to refrigerate your oils, though use them frequently, it would be best to pour yourself a smaller bottle that's not kept refrigerated, as taking the oil from cool to warm to cool to warm (etc.) isn't ideal (frequent change in temperature can affect the oils too, and they can collect moisture if this is done often as well).
The bottom line is that as long as you're storing your oils properly, there's really no reason to be concerned about their "shelf life", should you expect to use them within two years of their purchase.
Shelf Life and Carrier Oils
Carrier oils are more like food than essential oils. Some can go rancid, and some do this faster than others. Oils with the most unsaturated fatty acids are the most sensitive. Hempseed, with it's high amount of omega-3's, Sunflower, Borage Seed, Rosehip Seed, Avocado, and Evening Primrose oils are best kept refrigerated if they'll be kept for longer than a month.
At the other end of the spectrum, Jojoba and Fractionated Coconut last for years, without need for keeping them cool. And to extend the life of ALL carrier oils, you can add a few drops per ounce of vitamin E, or even better, Rosemary Antioxidant (it's more effective because of the way it quenches oxidative radicals). This is a good idea when making blends that may not be used very quickly as well.
We hope this helps you understand about shelf lives and essential oils! It is a complicated subject, because each oil ages differently. At the same time, it's easy to keep them fresh, simply by with proper storage.