Oils, whether they be vegetable and plant oils in a
jar, or oils that make up the cell membranes of an organism are prone to
oxidation and degradation. This oxidation can be stopped by antioxidants,
particularly vitamin E.
Oils are mainly triglycerides which are composed of
fatty acids. These fatty acids are carbon chains that consist of either double
bonds or single bonds between the carbons.
Carbon chains containing single bonds are known as saturated fatty acids
while those with one or more double bonds are referred to as unsaturated. It is
the unsaturated fatty acids that are more prone to oxidation and the risk of
oxidation increases with the number of double bonds.
This oxidation is initiated by light, heat, metals or
oxygen, so keeping oils away from these helps to slow oxidation, but it is
inevitable. A free radical contains an unpaired electron which makes it highly
reactive and unstable. It is looking for an electron on another molecule to
steal, thus setting up a chain reaction of forming free radicals. When these
oxidative products are formed from oils the breakdown products are off flavor
compounds such as ketones, aldehydes, alcohols and more. They tend to have a characteristic
smell known as ‘rancid’.
Your body is constantly making free radicals, and at
the same time making antioxidants to stop them from causing damage. Hopefully,
a nice balance exists, but not always. The oil in a bottle on your shelf or
your newly made skin care product has no way to make antioxidants like your
body does so it is helpful to add an antioxidant to prevent oxidation.
Vitamin E is an important oil soluble antioxidant to protect
polyunsaturated fatty acids and other cell membrane components from oxidation. Vitamin
E reacts with a lipid radical faster than that lipid radical can react with
other lipids and so suppresses the propagation of oxidation. It does this by transferring a hydrogen atom
to a lipid free radical. Of course now the vitamin E molecule becomes a free
radical but it can react with another vitamin E free radical to form a
non-radical product. This terminates the chain reaction of oxidation.
Vitamin E is a family of eight different molecules; 4
tocopherols and 4 tocotrienols. Vitamin E is high in wheat germ oil, canola oil,
and almond oil, but commercially, vitamin E is typically extracted from soybean
oil. Buy your vitamin E from a skin care ingredient supplier, do not use capsules from the store as this is not pure vitamin E.
Bottom line
is that your skin care products should contain an antioxidant such as vitamin E
to prevent the breakdown of oils in your product. Many crafters are being taught that this
is similar to a preservative that will prevent the growth of bacteria or fungus
in a product where it is not at all similar. If you have a product that
contains any form of water, you need to have a preservative to prevent growth
of microbes. Vitamin E will not prevent growth of microbes, but vitamin E
should be in your products that contain oil to prevent the breakdown of these
oils.
To learn more about preservatives (anti-microbials) see this post on What is the Best Preservative?
