Vegetable oils are mainly composed of fatty acids and it is these different molecules that give the oils their cosmetic, nutritional and therapeutic properties. But be careful, fatty acids often mean oxidation! And it is this oxidation which will harm the quality of your oil, apart from the choice of raw material at the start obviously. So how do you choose good quality vegetable oils and, above all, how do you store them properly? We explain everything to you here.
How to recognize a quality vegetable oil?
Mentions and certifications
Just like essential oils, there are many grades of vegetable oils. To guarantee the quality of your vegetable oil, you just need to pay attention to these few points:
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The mention virgin oil : this mention means that the oil has not undergone any treatment before or after pressing, it is a pure oil which has simply been filtered to remove any impurities.
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The mention first cold pressing : the first cold pressing is a simple, mechanical extraction method where oilseed fruits and seeds are pressed to directly extract the oil. It is possible to press by heating the raw material and pressing repeatedly to obtain more oil, but the quality will be lower.
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ORGANIC certifications : these certifications guarantee that the plant from which the oil was produced was produced according to the principles of Organic Farming, and that there are no phytosanitary products in it. Depending on how the vegetable, food or cosmetic oil is used, there are two types of certifications: AB and Cosmos.
Quality control
These different mentions ensure that the oil has been produced in the best possible conditions, however like essential oils, vegetable oils are natural products and their final quality depends initially on the raw materials selected.
Indeed, if the raw material is of poor quality, the finished product will also be poor, regardless of the skills of the processor. And to ensure that an oil contains all the molecules we are looking for, there is only one solution:chromatographic analysis ! It alone allows us to know precisely which molecules are present in the oil and in what proportion.
This is why the composition of the oils is carefully analyzed to guarantee the best possible quality. Small subtlety for oily macerates, it is important to check both thebiological origin of carrier oil, often sunflower oil, as well asorigin of the plant used in maceration.
Good to know
It is possible to see tocopherol mentioned in the list of ingredients on the label of certain vegetable oils. This is actually the other name for vitamin E, which is an antioxidant. It is often added to vegetable oils or oily macerates that are most sensitive to oxidation, to increase their stability and thus preserve them for longer.
What should the label of a vegetable oil contain?
On the label of a quality vegetable oil, you must find:
- The botanical name in French and Latin provides more information on the type of plant used to produce vegetable oil.
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There method of obtaining with the mentions virgin oil of first cold pressing
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THE certifications with the COSMOS ORGANIC logo certified by Ecocert or the AB and Eurofeuille logos certified by Ecocert FR-BIO-01.
- The list of ingredients ideally with the chemical composition and the part of the plant used.
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THE Batch number, l'geographic origin and tHE contact details from the manufacturer are a guarantee of traceability
How to store vegetable oils?
If essential oils are rather stable products that can be stored for several years at room temperature, vegetable oils are less stable and will age more quickly, particularly because of their fatty acid composition.
Oxidation of vegetable oils
Vegetable oils are often defined by their oxidative potential, this is a breakdown of fatty acids which make up the oil and which therefore go alter the quality of the oil. This oxidation can be caused by different factors:
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Oxygen in the air : an oil in contact with air can in the long term alter the molecular structure of fatty acids and thus modify the structure of the oil. This phenomenon of oil alteration is explained by the fixation of oxygen atoms on the carboxylic acid functions of the fatty acid.
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The light : UV rays are factors in the degradation of the bonds between the atoms forming fatty acids. Thus, too frequent exposure to light can lead to the formation of free radicals and mutations altering the quality of the oil.
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Interactions with the container : metal packaging, such as iron or copper, can react with the contents and release molecules which will degrade the oil.
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The heat : it is known that heat acts as a catalyst in these reactions, that is to say that it will promote the denaturation of fatty acids and therefore lead to the oxidation of the oil. Although some oils are less sensitive to heat than others, it is important to store them in a cool place.
These factors can therefore promote the oxidation of oils and consequently lead to allergic reactions, of the buttons (because an oxidized oil becomes very comedogenic) and a rancid smell when using. It is therefore important to store your oils away from heat and light, but also in a cool and dry place to avoid any contamination from micro-organisms and in a suitable container! Virgin oil extracted by first cold pressing is richer and will therefore tend to degrade more quickly than mineral oils. This is why it is essential to take care of the conservation of your vegetable oils.
Here are some examples of vegetable oils classified according to their oxidation stability:
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Excellent: the oil of Coco, the oil of Jojoba or the oil of Sesame.
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Good : the oil of Apricot kernels, oilArgan or oilAlmond.
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Sensitive to very sensitive: the oily macerate ofArnica, the oil of Borage or the oil of Wheat germ.
Good gestures
To put all the chances on your side and use your oils for as long as possible, take care of them. always store away from light, in a closed bottle. Wipe the neck of the bottle well after each use to avoid contamination and oxidation. And choose containers of a suitable size: the more the oil is in contact with air, the quicker it will oxidize.
Conservation of vegetable oils
For conservation, oils can be grouped into four categories according to their nature and their stability to oxidation.
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