My opinion?? I am sort of one of those myth busters. Now think this through. They were steam distilled- Did the heat destroy them? When I learned something about steam I thought I learned that water turns to steam somewhere around 212 degrees F at sea level, a little less as you go higher in elevation. Still, I know it can get hot inside of a car on a hot day, but I doubt it gets that hot.
Cold? I have purposely, and by accident, set or left bottles of oils out side in all weather conditions. Sometimes I have forgotten about them and several years have gone by, even to point of the label being about weathered off. Sometimes, I left some oils in my tool box. Sometimes in a car. Sometimes I have found oils in my Vet kit from having used them on animals and just forgot about them. They were subject to all sorts of weather conditions from as cold as it gets outside to as hot as it gets outside.
When I noticed them, I said to myself, "Ah crap, I guess I ruined some good oils." But just to be sure, and out of curiosity I opened them. You know what I found out? It seems like the aroma was a little off, usually a little bit more mellow. But testing against a control bottle in proper storage conditions, there ishardly any difference. How did they work? Pretty good, not too much deterioration, in fact hardly any at all.
In the end, there are a lot of myths about oil temperatures. Yes, some oils go solid when they reach a certain point in low temp. Warm them up and away you go. So I have come to the conclusion, based on many factors, that most oils and their quality have everything to do with the conditions of the plant from which it comes. Oils from plants that are not in the best condition, usually grown in soil that is less than ideal for the given plant, has a far heavier influence in how well the plant deals with extremes in temperatures. For example, people that are not subject to proper nutrition, don't do well when placed under stress or as well as they would naturally do, if their nutrition was up to par. Oils are the same way, if their original plant they were sourced from was "sick" then the oils won't do good under stressful conditions. If the plant was healthy, then they can handle a lot of stress. (This is something that no GC/MS can specifically test for). Also, I have noticed that the shelf life of many oils, actually pretty much all of them, are directly related to the health of the plant from which the oil was obtained. There is ways of determining this, but that would take a long explanation that changes the objective of this blog post.
However, there is one aspect that actually does affect the quality of the oils and that is oxygen. When oils are left out under conditions such as I have done, then you will find that the amount of deterioration is directly related to the amount of oxygen in the bottle. The bottles that I ran tests on actually had very few drops pulled from them. So the amount of oxygen in the bottle was at a very minimum. I also had the lids on very tightly. One of the big factors that can occur in extremes in heat levels is the expansion and contraction of the glass and plastic of the lids do so at different rates. So if the lid is not tight enough to withstand the varying expansion and contraction rates, it can cause the lid to become loose. Loose enough to allow a fresh supply of oxygen to interact with the oils. That in turn causes the oils to deteriorate as this exposure is run over a length of time. . So who gets the blame? The extremes in temperature. When the real vandal is the oxygen.
In the end, does extremes in temperatures that the essential oils are subject to affect their quality? Directly.. not likely. Indirectly or in a round about way, perhaps that is true to the extent that the answer would have to be yes, for the reasons that I have listed above.
Still it is a good idea to store them under normal good conditions. But most people will sometimes question the whole idea and most people still will default to the myths and that will affect their ability to gain an otherwise positive experience with the oils. Just my opinion, and I am sticking to it.
Written by Leiann King.