February 19, 2016

Debunking Dangerous Myths About Essential Oils Shelf Life

aromatherapy should not be faith-based

There is always a place for faith in our lives, be it faith in our friends or in God or in ourselves. Faith is what carries us through tough times and bids us closer to those whom we love. But we need to leave our faith at the office door when we read about claims for products made by marketers. Today, we examine the claims made for essential oils shelf life.

It’s a sad fact that even with essentially excellent products such as pure essential oils, marketers still feel the need to exaggerate to the point of lying. I really cannot imagine why so many silly claims are made for essential oils, when you could fill a pile of books with the wonderful facts about these oils which are scientifically proven and really true!

We have gathered information on this subject from our own experience and from a particularly good article on the website of the American College of Healthcare Sciences (link and accreditation below the article).

The Myth of Essential Oils Shelf Life

A commonly believed myth is that pure and unadulterated essential oils don’t expire and can last for centuries(!). This belief can have damaging consequences and can be debunked with a deeper understanding of the properties of essential oils and their constituents. Let’s take a closer look.

This belief appears to be based on the articles about the composition of mummy embalming fluids (preservatives) published in the journal Nature in 2001 and 2004.
While these and follow-up studies revealed that fragrant plant materials were used in the embalming process, they do not remotely suggest that essential oils do not degrade or oxidize.

Resins of coniferous trees and myrrh, not pure essential oils, were used as embalming materials. A few diterpenoid acids (these compounds are present in resins and are not found in essential oils) and numerous products of their degradation were identified upon detailed chemical analysis of the materials. Additionally, simple chemistry can show us why and how essential oils degrade with time.

A little chemistry background

Essential oils are complex mixtures. Their medicinal benefits come from active constituents like monoterpenes, sesquiterpenes, monoterpenoids, and sesquiterpenoids. These are compounds consisting of 10 (mono-) or 15 (sesqui-) carbon atoms that may also have an oxygen atom attached to them in the form of alcohol, aldehyde, acid, or ketone group (-oid). They also always contain a few carbon—carbon double bonds—unstable bonds that are characteristic for unsaturated fatty acids.

When monoterpenoids and sesquiterpenoids are exposed to air, they tend to undergo the following oxidation process: alcohol is transformed to aldehyde, aldehyde may turn into acid. Sound familiar? This is the same process responsible for spoiling wine and turning it to vinegar when it is accidentally exposed to air during storage.

Some monoterpenoids, such as geraniol (which is also an alcohol found in essential oils like geranium Pelargonium graveolens (L’Her.) and grapefruit Citrus paradisi (Macfad.)) are more prone to oxidation. Others, such as linalool (found in essential oils like immortelle Helichrysum italicum (Roth) and lavender Lavandula angustifolia (Mill.)), are more stable.

In addition, carbon-carbon double bonds can also open into single bonds and grab oxygen atoms forming oxides, epoxides, and peroxides.

Have you ever had a bottle of unsaturated vegetable oil go rancid in your cupboard? Did you notice the “off” odor of the oil? It’s the same chemical process. Since nearly all essential oil constituents are unsaturated compounds containing carbon, essential oils can undergo this same reaction and spoil or oxidize. While in the case of essential oils, this process does not usually produce the unpleasant odor (though oxidized citrus and other essential oils rich with limonene develop a rather unpleasant smell), and oxidized essential oils should be avoided.

With the rare exception of patchouli Pogostemon cablin (Blanco), sandalwood Santalum spp., and vetiver Chrysopogon zizanioides (L.), oxidation spoils essential oils and degrades their aromatic quality and therapeutic properties. In addition, it leads to the formation of skin irritants and potent allergens. Exposure to spoiled essential oils may cause skin rashes and more serious allergic reactions. Drastic change in the aroma and consistency (thickening or clouding) of essential oil are good indicators that your oil has oxidized and spoiled.

What makes essential oils go bad?

Degradation of essential oils is ususally triggered by one (or a combination of) the following:-

Oxygen

Oxygen that gets into your bottle and reacts with some of the constituents is called oxidation. This oxidation can affect the therapeutic properties of the essential oil, as well as render it more hazardous (source). The biggest hazard is increased risk for sensitization.

Heat

Heat causes the more volatile constituents to evaporate more quickly. CO2 extracts are more prone to damage from heat than steam-distilled essential oils (source).

Light

Ultraviolet light promotes free radicals. Amber colored bottles are best at keeping UV light out. Cobalt (blue being the opposite color of brown) bottles do not do a very good job of keeping UV light out, and they allow the light to pass through the glass more readily, and therefore into the oil.

So What Is the Shelf Life of Essential Oils and Carrier Oils?

When properly stored, pure essential oils should last about two years minimum and up to five years. No essential oil has to be discarded though, even if you know it is past its therapeutic effective shelf life – you can still use them for cleaning, freshening and scenting.

What about Carrier Oils?

The majority of carrier oils have a shelf life of around 2 years when stored in the refrigerator. They will start to go rancid even earlier if not kept in a cool place also. Some carrier oils such as Borage and Evening Primrose are extremely susceptible to oxidation and after 6-8 months will need to be discarded.

Accreditation

The above information was mainly extracted from an article on the website of American College of Healthcare Sciences and . We thank them for the valuable information and encourage you to visit them via the link provided.

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KeithR

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