Accepting variety in Aromatherapy Products
The change in the chemical composition of essential oils is influenced by soil conditions, climate and farming method among many other things, it makes sense that their values differ from place to place or batch to batch. This is why it is so important to request a GC-MS when you purchase your essential oils as they will give you the amount of key components in your oil. Not one from 10 years ago or a different batch to that oil you have received.
Essential oils and their components have important functions within the plant, such as pest defence and pollinator attraction. Considering this, essential oil components are important to the survival of the plant suggesting that the ability of the plant to respond to the external environment explains the differing amounts of chemical components batch to batch. The function will change depending on the overall plant health and what it needs from these secondary oils.
Harvesting an essential oil-bearing plant at different stages in its development can have an effect on both the yield and composition of the essential oil. This was reviewed by Gora et al. (2002), who stated that while the amount of some oils, such as pine and eucalyptus, stay the same throughout the plant’s life cycle, the essential oil content of some oils increase throughout the life cycle, whereas others such as peppermint and geranium have a maximum content before blooming.
The season in which essential oil-bearing plants are harvested can also have a significant impact upon particular essential oil components. A study on sage found that 1,8-cineole, camphene, camphor, cis-thujone and limonene increased towards the winter months, while other components had a higher concentration in spring.
Variety in weather conditions such as drought can lead to plant stresses, which affect essential oil production. For instance, under drought conditions, pine oil has been found to produce a decreased amount of terpenes because drought stress can limit photosynthesis and alter carbon and nutrient uptake. With more delicate plant material such as jasmine it can be the time of day picked and how long the material is left before the distillation process is started that can alter the chemical makeup of the final oil.
With this in mind as a consumer you must be prepared for differences in scent of batches of aromatherapy based products whether that’s an essential oil itself or a finished product you are buying such as a candle or skin oil.
Be bold if it is too different ask the manufacturer, they should be able to turn to you and explain why – perhaps it was a wet year or maybe it’s from a different country. If they can’t you may want to think about changing suppliers.
Gora, J., Lis, A., Kula, J., Staniszweska, M. and Woloszyn, A. (2002) Chemical composition variability of essential oils in the ontogenesis of some plants. Flavour and Fragrance Journal, 17, pp. 445-451.