How Temperatures Affect Essential Oils
As winter storms begin to affect us, don't worry if your essential oils are delivered in cold weather, even if they have to sit outside for a good while. Cold or freezing temperatures will not harm oils, whether they are distilled, CO2 extracted, expressed, absolutes or a carrier. If your oils are ever chilled to the freezing point, our suggestion is to keep the caps on and let them warm up gradually to room temperature. They should be fine.
While I'm covering the temperature topic, we have friends in the deep south who want to know about the effects of heat on the essential oils. While we make every attempt to protect our essential oils from excessive heat, there are some simple things we can do to minimize compromizing the therapeutic value. The flash point of some essential oils is between 100-140F (38-60C), which means that the lightest oil components may temporarily separate, vaporizing in the sealed bottle. The good news is that once the bottle has cooled back down, these components condense and become liquid again, leaving their chemical makeup unaltered. If your essential oils get too warm, keep the caps on until they have cooled back down to room temperature. If you must open a bottle that is too warm, the lightest compounds may escape and alter the balance of the oil. In that case, your oil will likely not be as effective as before the incident.
Expressed oils such as Bergamot, Grapefruit, Lemon, Lime (although our Lime is distilled) Mandarin, Orange and Tangerine can be damaged by temperatures in excess of 100F (38C), and they need to be kept in moderate temperatures. Blends with these oils in them are included. We try to keep our citrus oils and blends that contain them in temperatures we feel comfortable in. If they have been subjected to temperatures over 90F, allow them to cool down before removing the caps. If damaged, they will smell different than when they were fresh, and the damage will reduce their therapeutic value and may cause skin irritation. Refrigeration extends shelf life.
Absolutes fragrances, such as Jasmine, are destroyed by excessive heat (90F or 32C). They are slightly more sensitive to heat than expressed oils. Normal room temperatures help them maintain their delicate chemistry. Refrigeration extends shelf life.
Carrier oils are typically cold pressed because heat makes them susceptible to undesirable alteration. When fatty oil molecules break down, we say they have become "rancid." Blends that contain carrier oils should be kept reasonably cool. Refrigeration extends shelf life.