Polyunsaturated fatty acids (PUFAs) are

fatty acids In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an B ...

that contain more than one

double bond In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betwee ...

in their backbone. This class includes many important compounds, such as

essential fatty acid Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them. Only two fatty acids are known to be essential for humans: alpha-linolenic ac ...

s and those that give

drying oil A drying oil is an oil that hardens to a tough, solid film after a period of exposure to air, at room temperature. The oil hardens through a chemical reaction in which the components crosslink (and hence, polymerize) by the action of oxygen (no ...

s their characteristic property. Polyunsaturated fatty acids can be classified in various groups by their chemical structure: * methylene-interrupted polyenes * conjugated fatty acids * other PUFAs Based on the length of their carbon backbone, they are sometimes classified in two groups: * short chain polyunsaturated fatty acids (SC-PUFA), with 18 carbon atoms * long-chain polyunsaturated fatty acids (LC-PUFA) with 20 or more carbon atoms

Dietary sources

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 In organic chemistry, a methylene bridge, methylene spacer, or methanediyl group is any part of a molecule with formula ; namely, a carbon atom bound to two hydrogen atoms and connected by single bonds to two other distinct atoms in the rest of t ...

(--). 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''

Omega-3

Omega-6

Omega-9

Conjugated fatty acids

Other polyunsaturated fatty acids

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 A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Ailments of unknown cause Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabo ...

chain reaction, which oxidizes the PUFAs into hydroperoxide, which further decomposes into a complex mixture of secondary products.

References

Citations

General References

* * * *{{cite journal , author= Heinz, title=Similarities and Differences in Lipid Metabolism of Chloroplasts Isolated from 18:3 and 16:3 Plants , journal=Plant Physiol , volume=72 , issue=2 , pages=273–279 , year=1983 , pmid=16662992 , doi= 10.1104/pp.72.2.273 , last2= Roughan , first2= PG , pmc= 1066223 Fatty acids Nutrition Nutrients pt:Gordura poliinsaturada