Fatty acids are a class of compounds composed of three elements: carbon, hydrogen and oxygen, and are the main components of neutral fats, phospholipids and glycolipids. Fatty acids can be divided into two categories, one is a saturated fatty acid without a carbon-carbon double bond in the molecule, such as stearic acid, soft acid, etc.; the other is an unsaturated fatty acid with one or several carbon-carbon double bonds in the molecule, the most common are oleic acid, oleic acid and so on.

Fatty acids:

Glycerol i esters containing large amounts of saturated fatty acids tend to be solid at room temperature, such as butter, suet, etc., mostly animal fats. Triglycerides containing more unsaturated fatty acids tend to be liquid at room temperature, such as corn oil, vegetable oil, etc. Most of the oils from plants and fish are triglycerides of unsaturated fatty acids.