Dear EG, Do Your Oils Have An Expiration Date?
“Pure essential oils do not have a shelf life.” We’ve heard it before and often get asked why EG’s essential oils have a shelf life. The short answer is that pure essential oils have an expiration. The explanation to this fact is chemistry-related but won’t require a bunsen burner or safety goggles, fortunately.
The chemistry of expiration
If you’ve read our past blog posts, you may have seen terms like monoterpenes, monoterpenols and sesquiterpenols before. These are three examples of chemical families which essential oils belong to. For example, Mandarin and other citrus oils are high in limonene, pinene, terpinene and other constituents ending in -ene, which one can gather by looking at a citrus GC/MS report. Constituents ending in -ene are considered monoterpenes. Monoterpenes characteristically have a low molecular weight, making them unstable and susceptible to oxidation, or the process of an oil decaying due to interaction with oxygen or heat. Thus, essential oils categorized as monoterpenes typically have the lowest shelf life, of about 1-2 years.
On the opposite end of the spectrum, sesquiterpenols such as Sandalwood, Vetiver, Patchouli and Cedarwood, have a higher molecular weight. Therefore, essential oils classified as sesquiterpenols have a much higher shelf life, generally ranging between 6-8 years. In between these two chemical families are monoterpenols, which have a shelf life between 3-5 years.
Rather than going through each GC/MS report and figuring out which chemical family your essential oil belongs to, we’ve simplified the process by adding a “Safety & Shelf Life” section to each oil’s product page.
How to store
With the shelf life in mind, what’s the best way to store essential oils? Since oils decay with oxidation, we recommend storing oils in a cool, dry and dark area. Refrigerating oils is an efficient way to keep oils fresh as it meets all three of these requirements. We suggest placing oils in a bag or container in the fridge, so your food doesn’t begin to taste like essential oils.
To prevent oxygen from interacting with your oils, you may continuously move oils to smaller containers to keep oxygen out. For example, when you use half of a 10 ml bottle, transfer the rest of the oil to a 5 ml bottle to keep out as much oxygen as possible. This is not necessary, but suggested if you wish to extend the shelf life of your oils.
Have a question for E.G.? Ask us in the comment section below!