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 or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, f ...
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 betw ...
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 (not ...
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
Cis or cis- may refer to:
Places
* Cis, Trentino, in Italy
* In Poland:
** Cis, Świętokrzyskie Voivodeship, south-central
** Cis, Warmian-Masurian Voivodeship, north
Math, science and biology
* cis (mathematics) (cis(''θ'')), a trigonome ...
'' 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 ...
(--). 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
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...
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
Hydroperoxides or peroxols are Chemical compound, compounds containing the hydroperoxide functional group (ROOH). If the R is organic, the compounds are called organic hydroperoxides. Such compounds are a subset of organic peroxides, which have t ...
, which further decomposes into a complex mixture of secondary products.
See also
*
Fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...
**
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 ...
*
Saturated fat
A saturated fat is a type of fat in which the fatty acid chains have all single bonds. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone and fatty acids that each contain a long linear or branched c ...
*
Unsaturated fat
An unsaturated fat is a fat or fatty acid in which there is at least one double bond within the fatty acid chain. A fatty acid chain is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond.
...
**
Monounsaturated fat
Monounsaturated fats are fatty acids that have one double bond in the fatty acid chain with all of the remainder carbon atoms being single-bonded. By contrast, polyunsaturated fats have more than one double bond.
Molecular description
Fatty aci ...
**
Polyunsaturated fat
Polyunsaturated fats are fats in which the constituent hydrocarbon chain possesses two or more carbon–carbon double bonds. Polyunsaturated fat can be found mostly in nuts, seeds, fish, seed oils, and oysters. "Unsaturated" refers to the fact tha ...
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