Fatty acid clusters (Unit 5 a)

FAT T Y A C I D C L U S T E R S A N D
R E A C T I O N A N D D E R I V AT I V E S
5 . 1 S a t u r a t e d f a t t y a c i d s
5 . 2 M o n o - e n e i c a c i d s
5 . 3 M e t h y l e n e - i n t e r r u p t e d p o l y u n s a t u r a t e d a c i d s
5 . 4 B r a n c h e d f a t t y a c i d s
11/3/2020 Dr. Mohammed Danish/CPB30303 Oil & Fat Technology 1

FATTY ACIDS
Characteristics of the fatty acids:
• Long straight chain carboxylic acids with no branching.
• Most common fatty acid chains contains 10-20 carbon atoms in the
chain.
• Usually, an even number of carbon in the chain, including the carboxyl
carbon.
• Fatty acid can be saturated or unsaturated, but usually no other
functional groups present in it.
• Any fatty acid that cannot synthesized by the body, but it required for
biological function is called an essential fatty acid.

NOMENCLATURE OF
FATTY ACIDS
• Fatty acids are known by it
trivial names, which
frequently chosen to indicate
the source of the acid. For
example: palmitic acid, oleic
acid, etc.
• Trivial names of fatty acid
are commonly used because
IUPAC names are
cumbersome, for example α-
eleostearic acid has IUPAC
name 9c11t13t-octadecenoic
acid
Trivial name Source of fatty acids
Palmitic acid 16:0 Palm oil
Oleic acid 18:1 Olive oil
Linoleic & Linolenic acid 18:2/18:3 Linseed oil
Ricinoleic acid 18:1 Castor oil (Ricinus
communis)
Arachidic acid 20:0 Ground nut oil
(Arachis hypogea)
Lauric acid 12:0

Systematic or trivial names are sometimes abbreviated to two or three capital letters, some example of it
given below:
• Gamma linolenic acid GLA
• Arachidonic acid AA
• Eicosapentaenoic acid EPA
• Docosahexaenoic acid DHA
• Another way of representing the fatty acid involves the use of numbers such as, 18:2, 18:0, etc.
• These numeric symbols describes as linoleic acid with 18 carbon (assumes straight chain) and two
unsaturated bonds (assumed to be cis-olefinic).

• Since there are many isomeric compound that could be represented by additional descriptions as given:
(1) 18:2 (9, 12) or 18:2 (Δ9, Δ12 ), (2) 18:2 (9c, 12c), (3) 18:2(9Z, 12Z), (4) 18:2 (n-6)
• All these refer to same fatty acids, the first indicates the position of the two unsaturated centers in C18
chain and counting from the – COOH carbon sometimes it can be represented through Δ sign, the second
and third confirms the cis or Z configuration of double bonds.
• The fourth represented the double bond position with respect to the CH3 end group, and this is done with
symbols such as ω6 or n-6, which indicated the first double bond appear at carbon-6, counting from the
methyl end group.
• In the absence of other information it is assumed that all the double bond is methyl- interrupted and have
the cis(Z) configuration.
• Symbols such as c, t, and e are used to show cis, trans, and ethylenic unsaturation; a (acetylenic) or y
(ynoic) is used to show triple bonds.

• The number of known natural fatty acids exceeds 1000, but only 20-50 of them is of common concern.
• Based on the survey of these 1000 structures, four general statement can be stated.
1. Naturally fatty acids are both saturated and unsaturated, they are mostly straight chain with even
number of carbon. The carbon chain C12-C22 is most common, but we can find straight chain fatty
acids from C2-C80. exception of odd number of carbon fatty acidheptadecanoic acid (C17), branched
chain fatty acids are isopalmitic and anteisononadecanoic, carbocyclic fatty acid unit are Sterculic and
Chaulmoogric.
2. Acids with one unsaturated center are usually olefinic compounds with cis (Z) configuration and with the
double bond in on of the limited number of preferred position. Most commonly 9th carbon atoms from
the carboxylic group (Δ9) or from methyl group (n-9). Exception petroselinic (6 c-18:1) and tariric 6t-
18:1).

3. Polyunsaturated fatty acids are mainly polyolefinic with a methyl-interrupted arrangement of double
bonds having cis (Z) configuration. The cis double bonds are separated from each other by one –CH2
groups as in arachidonic acid. The 1,4 pattern of unsaturation found in natural fatty acids. Exception of
it is biosynthesized acyclic isoprenoids which usually followed 1,3 (conjugated) or 1,5 pattern.
4. Fatty acid rarely have functional groups apart from the carboxyl groups and unsaturated bonds.
Exception to this rule are ricinoleic acid (12-hydroxy oleic acid) and vernolic acids (12, 13-epoxyoleic
acid).

MAJOR FATTY
ACIDS FOUND IN
LIPIDS
Based on the annual production of vegetable oilseeds, it has been estimated that
eight fatty acid account for about 97% of the total production:
• Lauric acid – 4%
• Myristic acid – 2%
• Palmitic acid – 11%
• Stearic acid – 4%
• Oleic acid – 34%
• Linoleic – 34%
• α-Linolenic acid – 5%
• Erucic acid – 3%

STRUCTURE OF FATTY ACIDS
• A fatty acid is nothing more than a long –CH2– chain with a carboxyl groups (COOH) at
the end of the chain.
• The –COOH gives it an acid property.

PHYSICAL PROPERTIES
OF FATTY ACIDS
Solubility in water:
• Long chain fatty acids are hydrophobic in
nature, less soluble in water.
• Double bonds in chain increase the
solubility of fatty acid in water.
Melting points:
• Depends on chain length and saturation
• Double bonds lead chain disorder and
low melting temperature.
• Saturated fatty acids are solid at room
temperature.

TYPES OF
FATTY ACIDS
The length of the carbon chain:
• Long chain
• Medium chain
• Short chain
The degree of unsaturation:
• Saturated
• Unsaturated
The location of double bonds
• Omega-3 fatty acids
• Omega-6 fatty acids

LENGTH OF CARBON
CHAIN IN FATTY ACIDS
• Short chain fatty acids contains less than 6
carbons.
• Medium chain fatty acids contains 6-10 carbons.
• Long chain fatty acids contains 12 or more
carbons.

SOME COMMON FATTY
ACIDS
• Butyric Acid
• Caproic Acid
• Caprylic Acid
• Capric Acid
• Lauric Acid
• Myristic Acid
• Palmitic Acid
• Stearic Acid
• Oleic Acid
• Linoleic Acid
• Linolenic Acid

DEGREE OF UNSATURATION
Fatty acids broadly classify as:
• Saturated fatty acid
• Unsaturated fatty acids (cis and Trans configuration)
The unsaturated fatty acid further classify as
• Monounsaturated fatty acids (MUFA)
• Polyunsaturated fatty acids (PUFA)

SATURATED FATTY ACIDS
• Saturated fatty acids have no double bond between the carbon atoms connected in the chain. Normal
aliphatic carboxylic acids with 4 or more carbon atoms are called fatty acids. In nature they occur with an
even number of carbon atoms, with few exceptions.
• Nomenclature: the first real fatty acid is called by its systematic name butanoic acid. Its common (trivial)
name is butyric acid.
Systematic
name
Trivial name Chain length m. p. (C) Triacylglycerol
m. p. (C)
Decanoic Capric acid 10:0 31.6 31.5
Dodecanoic Lauric acid 12:0 44.4 46.4
Tetradecanoic Myristic acid 14:0 54.3 57.0
Hexadecanoic Palmitic acid 16:0 62.9 --
Octadecanoic Stearic acid 18:0 70.0 73.1

PHYSICAL PROPERTIES OF SATURATED FATTY ACIDS
• Going along the series of saturated fatty acids from those of short chain length to those
of long chain length the physical state changes from liquid to a solid consistency.
• The saturated fatty acid of longest chain length having, under ambient temperature in
moderate climates, a wax-like appearance.
• The melting point (m.p.), boiling point (b.p.) and the refractive index all increase with
increasing chain length, whilst the density (d) decrease with increasing chain length.
• The shorter-chain members are easily distilled at atmospheric pressure, whereas the
longer-chain ones, which have very low vapour pressures, should preferably be distilled
under vacuum.

• The shortest-chain fatty acids with up to 12 carbon atoms (lauric acid) can be distilled
easily by steam distillation.
• Fatty acids with more than 12 carbons are not distilled even by steam under practical
conditions, because solubility of fatty acids decreased as increase in the number of
carbon in chain.
• However, nearly all fatty acids are at least fairly soluble or readily miscible with polar
(water, Alcohol, Ketones) and nonpolar (aliphatic, aromatic, branched and cyclic
hydrocarbons) solvents.

CHEMICAL PROPERTIES OF SATURATED FATTY ACIDS
• In general fatty acids are easily transformed by alkalis or metallic oxides to their
corresponding salts, called soaps.
• This neutralization reaction is easily performed even in heterogeneous phases.
• In spite of their saturated nature the saturated fatty acids are not quite inert.
• Free radicals initiate oxidation and halogenationprocesses which become very
enhanced at high pressures and elevated temperatures.

• The cleavage of the chain (rupture) and the formation of lower molecular weight
scission products at exaggerated reaction conditions (e.g. temperature above 300 °C)
are quite feasible.
• Heating to high temperatures in an inert atmosphere may cause decarboxylation of fatty
acids by loss of carbon dioxide, with the formation of hydrocarbon.

PALMITIC ACID
• Palmitic acid (16:0) is the most widely occurring saturated fatty acid.
• It is present in fish oil (10-30%), milk and body fat of land animals (up to 30%), in all
vegetable fats at levels of between 5-50%, palm oil (30-60%), Chinese vegetable tallow
(60-70%), lard (20-30%), and tallow from sheep and cattle (25-35%)

STEARIC ACID
• Stearic acid (18:0) is much less common than palmitic acid.
• Stearic acid is a typical saturated fatty acids with 18 carbon is the chain

• It is a major component of the tallow of ruminant aminals (5-40%), and a significant
component in a number of vegetable fat including cocoa butter (30-35%), Illipe or
Borneo tallow (40%), and shea butter (45%).
• Stearic acid is also easily made by hydrogenation of readily available oleic, linoleic ,
and linolenic acids.
• Saturated fatty acids of chain length greater than 18 carbon atoms are present at low
levels in a few seed oils and at higher levels only in a few uncommon sources.
• The C20-C30 members of fatty acids often present in waxes.

UNSATURATED FATTY ACIDS
• The fatty acids having hydrogen deficient carbon atoms bonded by double or triple
bonds are called unsaturated.
• According to the number of double bonds present they are called monounsaturated
(monoenoic) or polyunsaturated (polyenoic) fatty acids.

STRUCTURE OF OLEIC ACID
• A typical unsaturated fatty acids with 18 carbon in the chain.

CIS-TRANS FATTY ACIDS
• Cis-fatty acids: H’s are on the same side of the double bond; fold into U-like formation;
naturally occurring.
• Trans-fatty acids: H’s are on the opposite side of double bond, more linearoccurs in
partiall hydrogenated foods.

• Some more cis- and trans- fatty
acids.

LOCATIONS OF DOUBLE BONDS
• Polyunsaturated fatty acids (PUFA) are identified by position of the double bonds
nearest to the methyl (CH3 -- ) end of the carbon chain, this is described as a omega
(ω) number.
• If PUFA has firs double bond at carbon number 3 away from the methyl end is called
omega 3 fatty acids.
• If PUFA has firs double bond at carbon number 6 away from the methyl end is called
omega 6 fatty acids.

MONOENEIC ACIDS
• Monoeneic acids are those fatty acids which contain only one carbon
-carbon double bond (C=C) in the carbon chain.
• Example of such fatty acids are: Eicosenoic acid (20:1), Erucic acid
(22:1), palmitoleic acid (16:1), Oleic acid (18:1) etc.
• More than 100 monoene acids have been known to us, these acids
contains carbon in the range of C10-C30, among them C16, C18,
and C22 members are most common.
• Most have cis-(Z) configuration, and the most common location of
double bond are either Δ9 or n-9.
• The most common monoene is oleic acid (18:1 n-9c).

• The location of double bond in
the carbon chain also
influences the melting point of
monoenes,
• Both cis-and trans C18
monoenes are higher melting
point when the double bond is
at even positions than at odd
positions.
•

POLYUNSATURATED FATTY ACIDS
• When fatty acids contains two or more than two carbon-carbon
double bonds (C=C) in the carbon chain is called poly
unsaturated fatty acids.
• These fatty acids chemically reactive compared to monenes, as
the number of double bonds increased the chemical reactivity
increased.
• Polyunsaturated fatty acids with 2 to 6 double bonds are
considered nutritionally valuable.
• Vegetable oils are principal source of the two essential fatty
acids such as linoleic and linolenic acids.
• Essential fatty acids: are those fatty acids which must be
obtained from food sources because human body lacks the11/3/2020 Dr. Mohammed Danish/CPB30303 Oil & Fat Technology 30

EXAMPLES OF POLYUNSATURATED
FATTY ACIDS
• Linoleic:
source: Corn oil or safflower;
Chemical structure: 18:2 with double bonds in 9 and 12 position
from –COOH end. It is known as Omega-6.
• Linolenic:
Source: Canola and Soyabean oil
Chemical structure: 18:3 with double bonds in 9, 12 and 15
position known as omega 3.

DIETARY IMPORTANCE OF
• It stimulate skin and hair growth
• Maintaining bone health and reproductive capability
• Prevent eczema, hair loses, neurological dysfunction,
• Decrease LDL cholesterol
• Help fetus (baby) growth
• Prevent heart disease and arthritis blockage.

METHYLENE INTERRUPTED
• In polyunsaturated fatty acids, when two or more double bonds are separated by one –
CH2- groups are called methylene interrupted polyunsaturated fatty acids
• This pattern results from the operation of a few specific desaturates and chain-
elongation enzymes.

S L I D E S E N D H E R E !
T H A N K S F O R
Y O U R
AT T E N T I O N !
Dr. Mohammed Danish
Senior Lecturer, Food
Technology Section,
UniKL-MICET, Alor Gajah
78000, Melaka, Malaysia

Fatty acid clusters (Unit 5 a)

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