Essential oils are natural organic materials and as such have a finite useable life span. Although they do not typically have a best before date their effectiveness can diminish over time through oxidation or bacterial breakdown. Heat, sunlight and oxygen can attack the oils and cause their chemical structure to break down, the oils may then resinify and start to develop artifacts that detract from the oil’s quality and odour profile. Some of these reactions may also cause allergenic constituents to arise in the oil. Each essential oil has a different rate of degradation but the most susceptible group of oils are top note oils, mainly the citrus ones – these will need extra special care and attention. Thicker viscosity essential oils such as Patchouli, Vetiver and Sandalwood can actually mellow and improve with age.
There are a number of variables that determine the viability of a pure essential oil and there are no guarantees of how long an oil will last. Generally, well cared for oils will last for one to two years, although some might claim this time frame is longer. In order to maximise your oils shelf life Soulistic recommends that you follow these simple guidelines:
Reputable supplier: Ensure that you are buying 100% pure therapeutic grade essential oils. Specialist aromatherapy suppliers such as ourselves typically have a high turnover of oils which ensures a fresher purchase. If you do buy from a shop, make sure the oils haven’t been sitting in direct sunlight or under hot lights. Remember it is always best to buy little and often.
UV protection: Oils must be kept away from strong light and heat sources as these will accelerate the oxidation process. They should be kept in UV filtering, dark coloured glass. Keep your oils in the smallest possible sized bottles to reduce the amount of empty space in the container. Any empty space will be occupied by air which speeds up the rate of oxidation. It is best to rebottle your oils into smaller containers as they are used up! When using your oils remember to replace the caps as quickly as possible.
Temperature: An ideal temperature range would be from 5 to 10 deg C and as constant as possible.
Transportation: This should be kept to a minimum as any agitation to the oil in its vessel will increase the surface area exposed to the atmosphere and therefore the oxidation process.
Dates: Keep a record of when you purchased your oils and when you opened them so that you’ll be more aware of when they might be approaching the end of their life.
Checks: Always check! You should be able to detect if the oil is past its best. If the oil appears a different colour, has a different or acidic smell, or if it looks cloudy or thick (resinous) this indicates oxidation.