Shelf life varies a lot with carrier oils so I want to take a few minutes today to discuss why this happens and how to work with the oils so that they stay fresh as long as possible.
The four factors that impact the shelf life of carrier oils are time, temperature, light, and air. Control as many of these four factors as possible, and you can extend the shelf life of your oils.
First, let’s look at carrier oils most prone to going off rapidly. These are the oils high in polyunsaturated fatty acids, like grapeseed oil or evening primrose, hemp, and flax.
Why do oil high in polyunsaturated oils go off more quickly than other carriers?
Polyunsaturated oils have places on the carbon chain where hydrogen atoms are absent and oxygen can attach. And, when oxygen attaches to the chain, it oxidizes, causing the oils to become rancid. As oil oxidizes, it will start to smell off, and eventually, the oil will begin to dry.
Store oils in a cool, dark place. This is good practice for all oils but is especially important for the polyunsaturated dominant oils. Brown bottles also help keep light out which can help extend shelf life. These oils typically have a shelf life of six to 18 months with careful handling.
Here are a few more examples of polyunsaturated oils:
- rosehip seed oil
- walnut oil
- safflower oil
- soy oil
- borage seed oil
- black currant seed oil
- kiwi seed oil
Heating polyunsaturated oils safely
But, what about making salves with polyunsaturated oils? There is no single temperature that turns an oil rancid. Rather it is heat and light over time as well as exposure to the air that causes oxidation and eventually rancidity. When working with the oils to make salves, keep the time that they are heated as short as possible. Start a salve by melting waxes and any butters and other saturated oils, then add the polyunsaturated oils last so they don’t get overly heated.
What about oil that is a year old with a one-year shelf life? If it has been stored in a cool cupboard and never opened it is most likely fine. An exception would be hemp or flax which need to be refrigerated. Unopened oils that haven’t been exposed to air (oxygen) will hold up longer than opened oils.
Saturated oils & stability
The most stable oils are the saturated oils – these are the butters that are solid at room temperature – because they have more hydrogen attached to their carbon chains and so fewer places for oxygen to attach.
Monounsaturated oils and shelf life
Somewhere between saturated oils and polyunsaturated oils are carrier oils dominant in monounsaturated fatty acids. These don’t need refrigeration but cool, dark storage is essential. Monounsaturated oils last 12 to 18 months or longer depending on the type, storage method and other factors.
Monounsaturated oils are your olive oils, almond oil, avocado and others.
Tips for prolonging shelf life of a recipe or formula
Adding a few drops of vitamin E extract to your formulas will help preserve the oils. Vitamin E is an antioxidant that acts as a natural preservative by slowing oxidation.
Or you can add meadowfoam seed oil. Meadowfoam seed oil is liquid at room temperature – meaning it is unsaturated – but it has an exceptionally long fatty acid chain and can naturally extend the shelf life of other oils in a blend. So if you are using a lot of grapeseed oil, rosehip seed oil, and other less stable oils, add some meadowfoam oil to your blend to stabilize it.
A lot of variables
While dominant fatty acids give us some indication as to the shelf life of a specific carrier oil, there are a lot of variables. I’ve noticed that raspberry seed oil, despite being high in polyunsaturated fatty acids, holds up well over time. But then raspberry seed oil is high in anti-oxidants so it would make sense that those are protecting the oil to some degree.
What carrier oils are you working with and loving right now? Leave a comment below and share your thoughts.
I made some face mask with only hemp seed oil, honey and clay in November last year, I was very surprised that these mixture last until now (July) and still fine. However, another one mix with apricot kernel oil gone bad in 2 weeks. I thought the apricot kernel oil might gone bad before I used them in the mask, but the same apricot oil that I used for making balms are totally fine. Oil are very interesting thing, I bought your book to learn some more, it’s a very good book, and good to see some updates online, thank you for sharing your knowledge Susan.
Thank you, Susan! This subject is specially interesting to me. It is a MUST to learn about oils, this is fascinating!
What about SymDecanox HA as an efficient natural identical ingredient?
Oils are natural compounds which is what I am interested in. Never been drawn to imitating nature when she does such a great job. I don’t know what that is, sorry so I’m no help. You could ask in a formulating group perhaps.
I’m about to use apple seed oil. I think it should be okay if it’s not ingested, but would welcome any comments from anyone who has any experience with it. I plan, ultimately, to make a butter with it, using mango butter and beeswax.
Wondering about Argan, baobab, pracaxi, açaí?
Alice, those all have pretty decent shelf lives – just keep them cool and dark.
Thank you, Sue. This is a help to me for my craft projects. I appreciate your knowledge and your ability to make it understandable to me.
I was blending it with other oils however I started using it alone. Wonderful. I just ordered 4 more oils that I’m going to experiment using alone instead of in blends so I can get the feel of each
I keep mine in a small refrigerator, is that ok?
yes that’s fine, will help keep them longer and you could turn it up to about 55 degrees if it’s a dedicated refrigerator. That way they don’t get over cold. cool and dark