Polyunsaturated fatty acid

Polyunsaturated fatty acids (PUFAs) are fatty acids that contain more than one double bond in their backbone. This class includes many important compounds, such as essential fatty acids and those that give drying oils their characteristic property.
Polyunsaturated fatty acids can be classified in various groups by their chemical structure:
Based on the length of their carbon backbone, they are sometimes classified in two groups:
Types.
Methylene-interrupted polyenes.
These fatty acids have 2 or more "cis" double bonds that are separated from each other by a single methylene bridge (--). This form is also sometimes called a "divinylmethane pattern".
The essential fatty acids are all omega-3 and -6 methylene-interrupted fatty acids. "See more at Essential fatty acids—Nomenclature"
Function and effects.
"The biological effects of the ω-3 and ω-6 fatty acids are largely mediated by their mutual interactions, see Essential fatty acid interactions for detail."
Thermal degradation.
Polyunsaturated fatty acids in culinary oils undergo oxidative deterioration at temperatures of . The heating causes a free radical chain reaction, which oxidizes the PUFAs into hydroperoxide, which further decomposes into a complex mixture of secondary products.