OIL AND FAT TECHNOLOGY
1st WEEK
Food Lipids
• Definition:Nonpolar, hydrophobic, poorly water
soluble components which are soluble in
organic solvents such as alkanes (e.g. hexane)
• Includes fats: solid at room temperature
oils: liquid at room temperature
• Definition based on physical properties
Triglycerides
Fatty Acids
Primary topics
Phospholipids
Terpenes/Terpenoids
Steroids
Waxes
Oils and Fats
Major Component (%95-99)
Minor Components (%1-5)
Triglycerides
Triglyceride Derivatives
Non-Triglyceride Derivatives
Glycerol
Phospholipids
Free Fatty Acids
Sterols
Mono- and Diglycerides
Pigments
Vitamins
Antioxidants
Oxidation Products
Trace Metals
Hydrocarbons
Triglyceride Structure
•Food fats/oils are primarily triacylglycerols, commonly called
triglycerides.
–3 fatty acid chains on a glycerol backbone
O
H2C
OH
HC
OH
3 fatty acids
O
+
OH
glycerol
HO -
H2C
C - R2
HO -
O
C - R1
O
O
C - R2
O
C - R1
HC
HO H2C
O
O
C - R3
–One chiral carbon with 1-3 acyl groups
–simpler stereochemistry than sugars
–more possible substituents
+3H20
H2C
O C - R3
triacylglycerol
O
-C
R
acyl
GLYCERIDES
O
H2 C O C (CH2 )16 CH3
H2 C OH
HC
OH O
H2 C O C (CH2 )16 CH3
Monoglyceride (a - monostearin)
HC
OH O
H2 C O C (CH2 )16 CH3
Diglyceride (a, a' - distearin)
O
H2 C
HC
H2 C
O C (CH2 )16 CH3
O
O C (CH2 )14 CH3
O
( C18 )
O C
(C18 )
(CH2 )16 CH3
(C16 )
Triglyceride (b - palmityl distearin)
Oleic
Palmitic
OPP
Palmitic
a - oleodipalmitin
1 - oleodipalmitin
Linoleic
Oleic
LOO
Oleic
a - Linoleyldiolein
1 - Linoleyldiolein
Fatty Acids
O
R C OH
#1 Carbon
O
R C OH
Acid Group
Polar End - Hydrophilic End
Non-polar End - Hydrophobic End
(Fat-soluble tail)
Fatty Acid Structure
• R-groups on fatty acid chains are generally
linear hydrocarbons, e.g.
O
H- O -
CH2
C
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
which may be more simply represented as
H- O -
O
C
CH2
CH2
CH2
CH2
CH3
CH2
Fatty Acid Chain Representation
• The symbol  followed by the carbon number is
used to indicate the position of the double bond
E.g. 18:19
O
-O-
C
2
1
4
3
6
5
11
8
7
9
10
13
12
15
14
consists of 18 carbons with 1 double bond
located between the 9th and 10th carbon.
17
16
18
Saturated Fatty Acids
8
7
CH3 CH2
O
5
3
4
6
2
1
CH2 CH2 CH2 CH2 CH2 C OH
Octanoic Acid
Unsaturated Fatty Acids
8
CH3
7
CH2
5
6
CH2 CH2
4
CH2
O
3
2
1
CH2 CH2 C
OH
3 - Octenoic Acid
8
7
CH3 CH2
O
5
3
4
6
2
1
CH2 CH2 CH2 CH2 CH2 C OH
3, 6 - Octadienoic Acid
Short hand: 8:1 (3)
8:2 (3,6)
Important Food Fatty Acid
Constituents
Abbreviation
Systematic Name
Common Name
Symbol
4:0
Butanoic
Butyric
B
6:0
Hexanoic
Caproic
H
8:0
Octanoic
Caprylic
Oc
10:0
Decanoic
Capric
D
12:0
Dodecanoic
Lauric
La
14:0
Tetradecanoic
Myristic
M
16:0
Hexadecanoic
Palmitic
P
18:0
Octadecanoic
Stearic
St
18:1
9-Octadecenoic
Oleic
O
18:29,12
9,12-Octadecadienoic
Linoleic
L
18:3
9,12,15-Octadecatrienoic
Linolenic
Ln
20:0
Eicosanoic
Arachadic
A
20:4
5,8,11,14-Eicosatetraenoic
Arachadonic
An
22:1
13-Docosenoic
Erucic
E
Chain Lenght – Molecular Weight
Fatty Acids Common Name
General
Formula
Formula
CnH2nO2 C12H24O2
Mol
Weight (g)
200
C 12:0
Lauric
C 14:0
Myristic
CnH2nO2
C14H28O2
228
C 16:0
Palmitic
CnH2nO2
C16H32O2
256
C 18:0
Stearic
CnH2nO2
C18H36O2
284
C 18:1
Oleic
CnH2n-2O2 C18H34O2
282
C 18:2
Linoleic
CnH2n-4O2 C18H32O2
280
C 18:3
Linolenic
CnH2n-6O2 C18H30O2
278
Melting Points and Solubility in Water of Fatty Acids
Fatty Acids
M.P.(0C)
mg/100 ml
Soluble in H2O
C4
-8
-
C6
-4
970
C8
16
75
C10
31
6
C12
44
0.55
C14
54
0.18
Melting Point
Solubility in H O
C16
63
0.08
C18
70
0.04
Chain Length
2
Effects of Double Bonds on the Melting Points
F. A.
16:0
16:1
M.P.
18:0
18:1
18:2
18:3
20:0
20:4
# Double bonds
M. P. (0C)
60
1
63
16
-5
-11
75
-50
Triglycerides differ from each other in
regard to
• Number of Carbon Atoms in fatty acid
chains
• Number of double bonds
• Isomerization
• Distribution of FA on glycerol backbone
Analytical Methods
• Saponification Value
• Iodine Value
• Gas Chromatographic Analysis for Fatty
Acids
• Liquid Chromatography
Saponification Value
Saponification - hydrolysis of ester under alkaline
condition.
The saponification value of an oil or fat is defined
as the number of mg of potassium hydroxide
(KOH) required to neutralize the fatty acids
resulting from the complete hydrolysis of 1 g of
the sample.
Saponification Value
O
O C- R
O
HC O C- R +
O
H2C O C - R
triacylglycerol
H2C
3 K+OH -
H2C
OH
HC
OH
H2C OH
glycerol
O
+
3 KO -
Potassium salt
Similarly;
RCOOH
+
KOH
C-R
RCOO-K+
+
Glycerol
MG
+
KOH
RCOOK
+
Glycerol
DG
+
2KOH
2RCOOK
+
Glycerol
Saponification Value
1 mol TG
1 g TG
3 mol KOH required
X mol KOH required
MWKOH: 56 g = 56000 mg
1 g TG : 1 g / MWTG (g/mol) mol
1 mol TG
1 g TG / MWTG
3x 56000 mg KOH required
X mg KOH required
168000
X  SN 
MWTG
Saponification Value
168000
X  SV 
MWTG
• What is the MWTG ?
H2C
HC
H2C
O
O
O C- R
O
O C- R
O
O C-R
O C - R1
O
O C- R1
O
O C - R2
H2C
HC
H2C
O
H2C
HC
H2C
O C - R1
O
O C- R2
O
O C - R3
Saponification Value
168000
X  SV 
MWTG
• Which one’s MW should be taken?
H2C
HC
H2C
O
O
O C- R
O
O C- R
O
O C-R
O C - R1
O
O C- R1
O
O C - R2
H2C
HC
H2C
O
H2C
HC
H2C
O C - R1
O
O C- R2
O
O C - R3
Saponification Value
168000
X  SV 
AMWTG
• The Answer is the Weighted Average MW
H2C
HC
H2C
O
O
O C- R
O
O C- R
O
O C-R
O C - R1
O
O C- R1
O
O C - R2
H2C
HC
H2C
O
H2C
HC
H2C
O C - R1
O
O C- R2
O
O C - R3
Saponification Value
Calculation of AMWTG
Oil consists of only type Simple Triglyceride
O
H2C
HC
H2C
O C- R
O
O C- R
O
O C-R
AMWTG  41  3  (MWFA R - 1)
Saponification Value
Calculation of AMWTG
Oil consists of Simple and Mixed type Triglyceride with
two fatty acids R1 (%90 w/w) and R2 (%10 w/w)
O
O
O
O
H2C
O C - R1
O
H2C
O C - R1
O
H2C
O C - R2
O
H2C
O C - R1
O
HC
O C- R1
O
HC
O C- R1
O
HC
O C- R2
O
HC
O C- R2
O
H2C
O C - R1
H2C
O C - R2
H2C
O C - R2
H2C
O C - R2
AMWTG  41 3 [(xR1  MWFAR1  x R 2  MWFAR 2 ) -1]
Average Moleculer Weight of FAs in Oil
(AMWFA)
Saponification Value
Generalized Calculation of AMWTG
Oil consists of Simple and Mixed type Triglyceride with N
fatty acids
FA
R1
R2
.
.
RN
xi
x1
x2
.
.
xN

AMWTG  41  3  [(
N
i 1
x R i  MWFAR i ) - 1]
Saponification Value
168000
SV 

AMWTG 41  [3  (
Fat
168000

N
i 1
x R i  MW FA R i  1)]
SV
Milk Fat
210-233
Coconut Oil
250-264
Cotton Seed Oil
189-198
Soybean Oil
189-195
Lard
190-202
Iodine Number
•
The iodine value of an oil or fat is defined as the mass of iodine absorbed by
100 g of the sample.
•
The unsaturated fatty acid residues of the glycerides react with iodine, and
thus the iodine value indicates the degree of unsaturation of the fatty acid
residues of the glycerides.
•
It is constant for a particular oil or fat, but depends on the method used.
Animal fats (butter, dripping, lard) 30 - 70 Iodine Value
• Non-drying oils (olive, almond) 80 - 110 Iodine Value
• Semi-drying oils (cottonseed, sesame, soya) 80 - 140 Iodine Value
• Drying oils (linseed, sunflower) 120 - 200 Iodine Value
•
The iodine value is often most useful in identifying the source of an oil.
Generally, the higher iodine values indicate oils and the lower values fats.
Iodine values are normally determined using Wigs or Hanus methods.
Determination of Iodine Number
Iodine Value = (ml of Na2S2O3 volume for blank - ml of Na2S2O3
volume for sample)  N of Na2S2O3  0.127g/meq  100
Weight of Sample (g)
CH
CH
CH
Cl
+ ICl
Iodine chloride
Excess unreacted ICl
ICl
I2 +
+
KI
2 Na2 S2 O3
KCl
+
Na2 S4 O6
I2
+ 2 NaI
CH
I
Theoretical Iodine Value
• Monoene + I2
• Diene + 2*I2
• Triene +3* I2
Saturated
Saturated
Saturated
Assumption: Oil =TG
Sample: 100 g basis
FA
C16:0
C18:0
C18:1
C18:2
C18:3
C20:0
xi
5
15
15
40
1
3
Theoretical Iodine Value
1 mol C18:1
15 g C18:1
1 mol I2 (254 g)
X (g) I2
IVC18:1
1 mol C18:2
40 g C18:2
IVC18:2
15  254

282
Assumption:
Oil =TG
FA
C16:0
C18:0
C18:1
C18:2
C18:3
C20:0
2 mol I2 (2x254 g)
X (g) I2
40  2  254

280
xi
5
15
15
40
1
3
Theoretical Iodine Value
1 mol C18:3
1 g C18:3
3 mol I2 (3x254 g)
X (g) I2
IVC18:3
1 3  254

276
Theoritical IV= IV C18:1 + IV C18:2+ IV C18:2
Real IV= 0.95xTheoricital Value