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Triglycerides and Skin Care

Posted by on May 28, 2010 · 5 Comments 

I thought I would do a series of blog entries on chemistry concepts that are important to the cosmetics crafter.  But before we get started, if you are planning on making your products ‘chemical free’ I suggest you think otherwise. Our bodies themselves are composed of chemicals and everything we put in or on our body is composed of chemicals. With some knowledge of chemistry we can find out which of these chemicals are safe, effective and actually good for us.

Lipids could be considered the most important part of skin care products. They are able to protect the skin from water loss, helping the barrier function of the skin. Lipids are defined by their ability to be soluble in organic solvents. In general lipids are used by mammals like us for energy reserves and to form cell membranes. The main lipid category is a triglyceride, also called a triacylglycerol. Other lipids include phospholipids, steroids and essential oils (for lack of any other category to put them). We’ll focus on the triglycerides alone though.

The structure of a triglyceride is a glycerol molecule as a backbone with three fatty acids attached to that. Since glycerol is a three carbon sugar, each fatty acid can bond to one of the carbons. Glycerine is also an alcohol as defined by the –OH groups.

glycerine

Below is a triglyceride. You can see the three carbon glycerin portion of the molecule on the left and the fatty acid chains to the right. Using this type of connotation each bend of the line represents a carbon atom.

Fatty acids are long chain hydrocarbons and identified by the number of carbons in their chain as well as by the number and placement of double bonds.

In this figure the first fatty acid from the top has16 carbons with no double bond. This fatty is abbreviated 16:0 and called palmitic acid. This fatty acid is saturated meaning that there are no double bonds in the chain. Each carbon atom is bonded to two hydrogen atoms (not shown) so the carbons are saturated with hydrogens.

The second fatty acid from the top has 18 carbons and one double bond. This is abbreviated 18:1 and is called oleic acid. Notice too that the double bond is at the ninth carbon.

The third fatty acid chain has 18 carbons again but three double bonds. This is abbreviated 18:3 and is referred to as alpha linolenic acid. This is an omega-3 fatty acid which refers to the fact that it has a double bond 3 carbons from the omega end of the chain.

So each different oil or fat you use in skin care is made up of triglycerides. Triglycerides found in different oils have different fatty acids associated with them which is referred to as the fatty acid profile. Various fatty acids can have different properties for skin care, a topic for another blog.

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More about the author:  Cindy Jones is a formulator and microbiologist. After receiving a Ph.D. in biochemistry from the University of Cincinnati she worked in cancer research, later as a health/medical writer and now in cosmetic science. Read more from this author

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  • http://www.neveroverthehill.com John C. Hill

    I think this is fantastic to post a primer on triglyceride oils and fatty acids. For the past decade or so, I have worked exclusively with botanical oils and research on their fatty acid profiles. I think it would be very good to expand on the basics. I think it is important for formulators to know that there are both inherently STABLE fatty acids, and inherently UNSTABLE fatty acids. By “unstable” I am refering to the ability of an oil to go “rancid”. If an oil has more than 5% polyunsaturated fatty acids (more than 5% double bonds in the carbon chain), then that oil is inherently unstable. It is critical to understand that no amount of anti-oxidants can stop an inherently unstable oil from going rancid. So, the age-old idea of loading up a formula with anti-oxidants like Vitamin E or BHT, etc, to prevent unstable oils from going rancid is futile. Unstable oils will go rancid no matter what. A list of inherently unstable oils would also look like a list of the most popular oils in cosmetics today: Avocado, Palm, Olive, Almond, Neem, Canola, Borage, Sesame, Wheat Germ, Corn, Soybean, Sunflower (low oleic content), Kukui, Chia, Grape, Rice Bran, Hemp, Safflower, and others. All of these oils have more than 5% polyunsaturated fatty acids, and will go rancid, causing the cosmetic product to potentially smell bad over time.

    To avoid this problem, it is best to formulate as much as possible with inherently stable botanical oils. These include things like Macadamia Oil (which also has a fatty acid profile very similar to that of natural skin sebum), Moringa Oil, Sunflower Oil (high oleic acid content), coconut, palm kernel, and cocoa butter, among others.

    There are other variables to consider when choosing emollient oils to include in cosmetic formulas. Because of the different fatty acid profiles of the different oils, you can create very different skin feel (slip, spread, penetration), and you can have good or bad water barrier capability.

    All of these variables should be considered as pieces of a puzzle, that when put together correctly, creates a formula that shows the full picture (full efficacy) that a consumer desires.

    John

  • http://greenskincareblog.com/ Kristin Fraser Cotte

    Thanks for your comments and sharing your knowledge John. If you ever want to contribute to Personal Care Truth, we encourage you to submit an article at the link in the top tool bar.

  • http://greenskincareblog.com/ Kristin Fraser Cotte

    Thanks for your comments and sharing your knowledge John. If you ever want to contribute to Personal Care Truth, we encourage you to submit an article at the link in the top tool bar.

  • http://www.apsaraskincare.com/ best natural face cream

    Interesting post. This is the first time I come across equations and chemistry in skin care. really good to know them. Thanks for sharing Cindy.

  • http://www.expederm.com organics skin care

    Loving every word of this blog post. Thanks for your diligence in testing :)