Fatty Acids and the Formulator
In our recent post on cosmetic emollients I mentioned that many of them were derived from triglycerides. Triglyceride molecules are made up of two segments including glycerin and fatty acids. Since fatty acids are the main components of many natural oils and used to create thousands of different types of cosmetic ingredients, it’s worthwhile to know a bit about them.
What is a fatty acid
Fatty acids are molecules made up of repeating units of Carbon attached to Hydrogen. One end of the molecule is capped off with a Carbon attached to two Oxygen atoms. This is called the Carboxyl group. (see picture). They are found widely in nature providing a natural way for living organisms to store energy. Common sources of fatty acids are natural oils like coconut oil, palm kernel oil, soybean oil, and sunflower oil. 
The number of carbons and hydrogens affects the physical and chemical properties of the fatty acid. In cosmetic products, fatty acids range in carbon length from 6 to 22. Much longer fatty acids can be produced but they are more rare and not normally used as cosmetic ingredients. Since these are produced through a natural biochemical reaction you typically find only even numbered carbon chains. That’s just how the mitochondria works.
Why are they used in cosmetics
Fatty acids are used in cosmetics for a number of reasons. First, they are emollients and can provide conditioning effects to both skin and hair. They are also good wetting agents which can make a formula feel more slippery on the skin.
Many fatty acids are starting materials for a number of cosmetic ingredients including cleansing surfactants, emulsifiers, esters, alcohols, and more. They are also chemically reacted and placed on polymers to provide flexibility and conditioning.
Natural Formulating
While fatty acids may not be superior to petroleum derived ingredients they do have the benefit of being sustainable and having a natural sounding name. This is useful when it comes to creating products that will be touted as natural.
