Chemistry of Natural Fats and Oils Used in Cosmetics

By: Kelly A. Dobos

Natural fats and oils used in cosmetic are primarily prepared from plant seeds or nuts. To understand the properties of these materials it is helpful to understand their chemistry and composition.

Fats and?oils?are composed of molecules known as triglycerides, which are esters composed of three?fatty acid?units linked to glycerol. Think of a fatty acid as a long chain. This chain is made of carbon atoms that are linked together. At one end of this chain, there's a special group called a carboxyl group which gives it the "acid" part of its name. In?saturated fatty acids, carbon atoms are bonded to as many hydrogen atoms as possible. This causes the molecules to form straight chains. The straight chains can be packed together very tightly and this explains why saturated fatty acids are solids at room temperature.?

In unsaturated fatty acids, some carbon atoms are not bonded to as many hydrogen atoms as possible due to the presence of one or more double bonds in the carbon chain. This causes the chains to bend and kink. The bent chains cannot pack together tightly, so unsaturated fatty acids are liquids at room temperature and highly unsaturated fats are prone to oxidation.

Generally, plant-derived oils tend to have a higher proportion of unsaturated fatty acids, while animal fats typically contain more saturated fatty acids. For example, vegetable oils like canola oil are rich in oleic acid which is monounsaturated and linoleic acid which is polyunsaturated. Animal fats like butter and tallow have higher amounts of saturated fatty acids such as palmitic and stearic acid.

While cocoa but and argan oil are comprised of similar fatty acids, the typical compositions for each is quite different. Cocoa butter, which contains a higher proportion of saturated fatty acids is a solid that melts melting typically happens between 32 and 34°Celsius which is 89.6 - 93.2°Farenheit. Argan oil on the other hand contains a higher proportion of unsaturated components and is a liquid at room temperature.??

The distribution of fatty acids in natural oils varies significantly depending on the source of the oil.? Most natural oils contain a combination of saturated, monounsaturated, and polyunsaturated fatty acids. The specific distribution of fatty acids in seed oils can vary based on factors such as plant species and environmental conditions like climate and soil conditions.

Natural oils and fats may have certain drawbacks in use including sustainability concerns, the possibility of adulteration - which is refers to cutting expensive exotic oils with cheaper materials, and susceptibility to oxidation that results in detrimental changes color, odor, and stability.

Natural oils remain popular and effective ingredients in cosmetic and personal care formulas to provide emollience and conditioning properties. Understanding the chemistry and properties of these ingredients you can ensure the development of successful and stable products.