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Oils composition
The oil is made up of :
-Triglycerids
- Free fatty acids (1 to 10% for the unrefined oils)
- Unsaponifiable matter (0.2 to 10% according to the
oils)
THE TRIGLYCERIDS
Composition
A triglycerid is made up of
3 fatty acids fixed to a glycerol molecule.
The fatty acids are made up of a chain of carbon atoms
(6 to 24), held together by simple or double bonds.
On these atoms of carbon are fixed atoms of hydrogen.
The insaturation
of oils
The level of insaturation of an oil is measured by
the iodine value (0 to 210 according to the oils).
- The saturated fatty
acids
When a fatty acid does not contain any double bond,
it is called ‘saturated fatty acid’.
- The mono-unsaturated fatty acids
When a fatty acid contains a double bond, it is called
a ‘monounsaturated fatty acid’.
The most frequent is the oleic acid (C18:1), it can
be found in every fatty body:
- It reduces total cholesterol and LDL;
- It simultaneously increases the rate
of LDL (good cholesterol).
It can be found in large quantities in olive oil,
this is why this oil is so trendy.
- The essential polyunsaturated
fatty acids
When a fatty acid contains several double bonds,
it is called a ‘polyunsaturated fatty acid’.
The human body cannot synthetize the two following
polyunsaturated fatty acids:
- The
linoleic acid (C18:2, omega 6)
- The
alpha linolenic acid (C18:3, omega 3)
This is why they are called essential fatty acids.
A good daily diet should supply them.
From them the body make up other polyunsaturated
fatty acids of which namely the EPA (C20:5) and the
DHA (C22:6) from the omega 3 family.
The linoleic acid is the precursor of the Omega 6
family ;
The alpha linolenic acid is the precursor of the
Omega 3 family.
Our everyday diet is too rich in Omega 6 and too
poor in Omega 3, this is why the high Omega 3 content
fish oils are so valuable (namely in EPA and DHA).
Physical properties
At room temperature, the unsaturated
fatty acids are liquid (oils) and the saturated fatty
acids are solid (fats).
Chemical formula
The fatty acids are identified by their number of carbons
and double bonds.
Examples :
C16 :0 : 16 carbons and 0 double bond (saturated),
palmitic acid
C18 :1 : 18 carbons and 1 double bond (monounsaturated),
oleic acid
C20 :5 : 20 carbons and 5 double bonds (polyunsatured),
eicosapentaenoic acid (EPA)
Fatty acids table
| |
Number
of carbons |
Number
of double bonds |
ENGLISH |
FRENCH |
C4:0 |
4 |
0 |
Butyric |
Butyrique |
C6:0 |
6 |
0 |
Caproic |
Caproïque |
C7:0 |
7 |
0 |
Heptanoic |
Heptylique |
C8: 0 |
8 |
0 |
Caprilic |
Caprylique |
C9:0 |
9 |
0 |
Pelargonic |
Pélargonique |
C10:0 |
10 |
0 |
Capric |
Caprique |
C11:0 |
11 |
0 |
Undecanoic |
Undécylique |
C12:0 |
12 |
0 |
Lauric |
Laurique |
C12:1 |
12 |
1 |
Lauroleic |
Lauroléique |
C14:0 |
14 |
0 |
Myristic |
Myristique |
C14:1ω5 |
14 |
1 |
Myristoleic |
Myristoléique |
C15 :0 |
15 |
0 |
Pentadecanoic |
Pentadécylique |
C15:1 ω 6 |
15 |
1 |
Pentadecenoic |
Pentadécènoique |
C16:0 |
16 |
0 |
Palmitic |
Palmitique |
C16:1 ω
7 |
16 |
1 |
Palmitoleic |
Palmitoléique |
C17:0 |
17 |
0 |
Heptadecanoic |
Margarique |
C17:1 ω
8 |
17 |
1 |
Heptadecenoic |
Héptadécénoïque |
C18:0 |
18 |
0 |
Stearic |
Stéarique |
C18:1 |
18
|
1
|
Oleic
|
Oléique |
C18:1 ω 7 |
18
|
1
|
Vaccenic
|
Vaccénique |
C18 :1 |
18
|
1
|
Ricinoleic
|
Ricinoléique |
C18:2 ω 6 |
18
|
2
|
Linoleic
|
Linoléique |
C18:3 ω 3 |
18
|
3
|
Alpha Linoleic
|
Alpha Linolénique |
C18:3 ω 6 |
18
|
3
|
Gamma Linolenic
|
Gamma Linolénique (GLA) |
C18:4 ω 3 |
18
|
4 |
Stearidonic |
Stéaridonique (moroctique) |
| C20:0 |
20 |
0 |
Arachidic |
Arachidique |
C20:1 ω 11 |
20
|
1
|
Icosenoic
|
Gadoléique |
C20:1 ω 9 |
20
|
1
|
Eicosenoic
|
Eicosénoïque (gondoïque) |
| C20:3 ω 6 |
20 |
3 |
Homo-gamma-linolenic
|
Homo-gamma-linolénique |
C20:4 ω 6 |
20
|
4
|
Eicosatetraenoic
|
Eicosatétraénoïque
(ETA) |
C20:4 ω 6 |
20
|
4
|
Arachidonic
|
Arachidonique |
C20:5 ω 3 |
20
|
5
|
Eicosapentaenoic
|
Eicosapentaénoïque
(EPA) |
C22:0 |
22
|
0
|
Behenic
|
Béhénique |
C22:1 |
22
|
1
|
Erucic/docosenoic
|
Erucique |
C22:1 ω 11 |
22
|
1
|
Cetoleic
|
Cétoléique |
C22:5 ω 3 |
22
|
5 |
Docosapentaenoic |
Docosapentaénoïque
(DPA) |
C22:5 ω 6 |
22
|
5 |
Docosapentaenoic
|
Docosapentaénoïque |
C22:6 ω3 |
22
|
6 |
Docosahexaenoic |
Docosahexaénoïque
(DHA) |
C24:0 |
24
|
0 |
Tetracosenoic |
Lignocérique |
C24:1 ω 9 |
24 |
1 |
Tetracosenoic |
Nervonique |
C26:0 |
26
|
0 |
Cerotic |
Hexacosanoïque |
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THE FREE FATTY ACIDS
The free fatty acids acids are not fixed to a molecule
of glycerol and thus are not easily assimilated by
the man.
The content of an oil in free fatty acids is expressed
by the oleic acidity.
Refining enables to remove these free fatty acids.
THE UNSAPONIFIABLE MATTER
Fraction that cannot be converted in soap.
According to the oils, it is made up
of :
- vitamins (A, D, E in tocopherol form)
- different sterols (the analysis of these components
gives a genetic map of the oil and enables a reliable
identification of the oils)
- waxes
- natural hydrocarbons (carotene, squalene,…)
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