Food Lipids

1
Food Lipids
2
Roles of Food Lipids

• Energy Source
• Carrier of Fat Soluble Vitamins
• Main Flavor Source of Foods
• Hormone and Cell Structure
• Nerve System
• Thermal Insulation of Body
• Mouth Feeling
• Texture of Foods
• Emulsifying Agents
• Mold Releasing and Anti-spattering Agent

3
Definition
Any of a group of substances that in general are
soluble in organic solvents, but are not soluble
in water.
4
Types of Lipids
  1. Fatty acids 2. Neutral fats and
oils 3. Waxes 4. Phospholipid 5. Sterols 6. Fat
soluble vitamins lipids
5
Fatty Acids
1 Carbon
Acid Group
Polar End - Hydrophilic End
Non-polar End - Hydrophobic End
(Fat-soluble tail)
6
Saturated Fatty Acids
Octanoic Acid
7
Unsaturated Fatty Acids
3 - Octenoic Acid
3, 6 - Octadienoic Acid
Short hand 81 (D3) 82 (D3,6)
8
Cis and Trans Fatty Acids
Cis 9 - Octadecenoic Acid (oleic)
Trans 9 - Octadecenoic Acid (elaidic acid)
9
Fatty Acids
10
Saturated and Unsaturated Fatty Acids
11
Polyunsaturated Fatty Acids
Linoleic acid Cis, cis, 9, 12 - Octadecadienoic
acid Linolenic acid Cis, cis, cis 9, 12, 15 -
Octadecatrienoic acid Arachidonic acid Cis,
cis, cis, cis 5, 8, 11, 14 - Eicosatetraenoic
acid   Linoleic Acid Linolenic
Acid Arachidonic Acid
12
Naturally-occurring Fatty Acids

O
CH CH CH
C OH
R CH
CH CH CH
2
2
2
n
4
3
7
6
5
1. Cis form 2. Not conjugated --- isolated double
bond. 3. Even numbered fatty acids.
13
Saturated Fatty Acids
 
Butyric
Butanoic
CH3(CH2)2COOH
butterfat
Caproic
Hexanoic
CH3(CH2)4COOH
butterfat, coconut, palm nut oils
Caprylic
Octanoic
CH3(CH2)6COOH
Coconut, palm, nut oils, butterfat
Capric
Decanoic
CH3(CH2)8COOH
Coconut, palm, nut oils, butterfat
Lauric
Dodecanoic
CH3(CH2)10COOH
Coconut, palm, nut oils, butterfat
Myristic
Tetradecanoic
CH3(CH2)12COOH
Coconut, palm, nut oil, animal fats
Palmitic
Hexadecanoic
CH3(CH2)14COOH
practically all animal, plant fats
Stearic
Octadecanoic
CH3(CH2)16COOH
animal fat, plant fats
Arachidic
Eicosanoic
CH3(CH2)18COOH
peanut oil
14
Unsaturated Fatty Acids
 
 
A. Monoethenoic Acids  
Oleic
Cis 9-octadecenoic
C17H33COOH
plant and animal fats
Elaidic
Trans 9-Octadecenoic
C17H33COOH
animal fats
B. Diethenoic Acids
Linoleic
9,12-Octadecadienoic
C17H31COOH
peanut, linseed, and cottonseed oils
C. Triethenoid Acids  
Linolenic
9,12,15-Octadecatrienoic
C17H29COOH
linseed and other seed oils
Eleostearic
9,11,13-Octadecatrienoic
C17H29COOH
peanut seed fats
D. Tetraethenoid Acids
4,8,12,15-Octadecatetraenoic
Moroctic
C17H27COOH
fish oils
15
Important Fatty Acids for Nutrition

• EPA (Eicosapentaenoic acid)
• 205(n-3). Omega-3, all-cis eicosa-5,8,11,14,17
  pentaenoic acid
• DHA (Docosahexaenoic acid)
• 226 (n-3). omega-3, all-cis
  -docosa-4,7,10,13,16,19-hexaenoic acid

16
Fatty Acids Melting Points and Solubility in Water
x
Melting Point
x
x
x
Melting Point
x
x
x
x
Solubility in H O
z
2
Fatty Acid Chain Length
17
Characteristics of Fatty Acids
C4
- 8
 -
C6
- 4
970
C8
16
75
C10
31
6
C12
44
0.55
C14
54
0.18
C16
63
0.08
Solubility
18
Effects of Double Bonds on the Melting Points
  60
160
161
1
180
63
181
16
182
-5
183
-11
200
75
x
x
x
x
19
FAT AND OILS
20
Triacylglycerol (Triglycerides )
O
O
H
C O C R
2
HO C R
H
C OH
O
2
O
HC OH
HC O C R
3 H
O
2

HO C R
O
H
C OH
O
2
H
C O C R
2
HO C R
Glycerol 3 Fatty Acids
21
Glycerides
Monoacylglycerol (Monoglyceride)
Diacylglycerol (Diglyceride)
Triacylglycerol (Triglyceride) (b - palmityl
distearin)
22
Monoacylglycerol (Monoglyceride)
23
Triacylglycerol (Triglyceride)
24
Triacylglycerol (Triglyceride)
25

• Fats and Oils
• World Supply
• Vegetable oil - 68
• Animal fat - 28
• Marine oil - 4

26
Fatty Acids () of Fats and Oils
4
3
 
 
 
6
3
 
 
 
8
2
6
 
 
10
3
6
 
 
12
3
44
 
 
14
10
18
1
 
16
26
11
4
12
161
7
 
1
 
2
180
15
6
3
181
29
7
18
24
182
2
2
53
54
27
Melting Points of Triglycerides
28
Waxes

• Fatty acid Long chain alcohol
• Important in fruits
• Natural protective layer in fruits, vegetables,
  etc.
• Added in some cases for appearance and
  protection.
• Beeswax (myricyl palmitate), Spermaceti (cetyl
  palmitate)

O
O
C
H
O C C
H
C
H
O C C
H
30
61
15
31
16
33
15
31
29
Phospholipid
Lecithin (phosphatidyl choline)
30
Sterols
Male female sex hormones Bile acids Vitamin
D Adrenal corticosteroids Cholesterol
21
22
18
20
12
19
16
17
11
13
14
15
10
1
9
2
8
3
7
6
4
5
31
Cholesterol
32
Fat Soluble Vitamins
Vitamin A
33
Vitamin D2
Vitamin E
34
Analytical Methods for The Determination of
Characteristics of Fats and Oils
35
Analytical Methods
1. Acid Value 2. Saponification Value 3. Iodine
Value 4. Gas Chromatographic Analysis for Fatty
Acids 5. Liquid Chromatography 6. Cholesterol
Determination
36
Glycerides

O
(
C
)
H
C O
C (CH
)
CH
18
2
2
16
3
O
HC O
(C
)
C (CH
)
CH
16
2
14
3
O
H
C O
(C
)
C (CH
)
CH
2
18
2
16
3
37
Acid Value
Number of mgs of KOH required to neutralize the
Free Fatty Acids in 1 g of fat.
RCOOH KOH ROO- K H2O
38
Acid Value
The free fatty acid content in a good soybean
oil should be less than or equal to 0.05 . The
average molecular weight of free fatty acids of
the oil is 280 which is the molecular weight of
linoleic aid. What is the maximum acid value
of the good soybean oil? What is the content
() of free fatty acids of a soybean oil if the
acid value is 0.3? The average molecular weight
of free fatty acids of the oil is 280.
39

• The free fatty acid content in soybean oil is
  0.05.
• What is the content of free fatty acid in 1g oil
  in mg?
• 1g 1000mg
• What is the 1 of 1000mg in mg?
• What is the 0.1 of 1000 mg soybean oil in mg?
• What are the 0.5 of 1000mg soybean oil in mg and
  ug?

40
Acid Value
0.05 in 1gram is 0.5 mg fatty acid in 1 gram
of oil 56 mg of KOH reacts with 280 mg of
RCOOH 280 mg of RCOOH / 56 mg of KOH 51 The
0.1 mg KOH reacts with 0.5 mg RCOOH Acid Value
is 0.1
41

• What is the content () of free fatty acids of
  soybean oil if the acid value is 0.3?
• Acid value 0.3 means that 0.3 mg KOH is required
  to react with the free fatty acid in1g (1000mg)
  of oil
• The 56mg KOH reacts with 280 mg free fatty acid,
  56 280 1 5
• 1mg KOH reacts with 5 mg free fatty acid
• The 0.3 mg KOH reacts with 1.5 mg of free fatty
  acid in 1 gram oil
• 1.5 mg free fatty acid /1000 mg oil x100() 0.15
  

42
Saponification Value
Saponification - Hydrolysis of ester
(triglycerider) under alkaline condition.

O
H
H
C O
2
H
C O
C R
O
2
Heat
O

R C O-K
H
HC O
3
KOH

3
HC O
C R
O
H
H
C O
2
H
C O
C R
2
Definition mgs of KOH required to saponify 1 g
of fat
43
Saponification Value
A
Tricaprylin (MW 450)
B
Tristearin (MW 890)
1Gram of Oils A and B
44
Saponification Value
Definition mgs of KOH required to saponify 1 g
of fat
B
A
Small molecular triacylglycerols
Large molecular triacylglycerols
45

• The molecular weights of tributyrin and
  tristearin are 300 and 900, respectively. If the
  numbers of tributyrin in 1 gram is 21 x 1020,
  what are the approximate numbers of tristearin in
  1 gram?
• If the saponification value is tristearin is 190,
  what is the approximate saponification value of
  tributyrin?

46
Sample A has large molecular weight triglyceride
(e.g. MW.890). Sample B has small molecular
weight triglyceride(e.g. MW.450). In one gram of
sample, number of triglyceride in B is about two
times more than number of triglyceride in
A. Less mg of KOH is needed to saponify sample A
than sample B. Therefore, saponification value of
A is about half of that of sample B
Avogadros Number (N) 6.02 x 1023 / mol
47
Brazil soybean oil has molecular weight of
900 Cuba special tropical oil has molecular
weight of 450.
Avogadros Number (N) 6.02 x 1023 / mol
48
Saponification Value Determination

• Saponification --mgs of KOH required to
  saponify 1 g of fat.
• 1. 5 g in 250 ml Erlenmeyer.
• 2. 50 ml KOH in Erlenmeyer.
• 3. Boil for saponification.
• 4. Titrate with HCl using phenolphthalein.
• Conduct blank determination.
• Saponification number (B S) x N of HCl x 56
  /gram of sample
• B - ml of HCl required to titrate KOH in Blank.
• S - ml of HCl required to titrate excess KOH by
  Sample.

49
The molecular weights of tributyrin and
tristearin are 302 and 900, respectively. If the
numbers of tributyrin in 1 grams is 21?1020, what
is the approximate numbers of tristearin in 1
gram. If the saponification value of the
tristerarin is 190, what is the approximate
saponification value of tributyrin.
50
A 5.00 rams of exotic tropical oil was
saponified with excess KOH. The unreacted KOH
was then titrated with 1.00 N HCl. The blank
required 40 mL of HCl and the sample required 20
mL. Please calculate the saponification value
of the oil.
51
Saponification Values of Fats and Oils
Milk Fat
210-233
Coconut Oil
250-264
Cotton Seed Oil
189-198
Soybean Oil
189-195
52
Fatty Acids () of Fats and Oils
4
3
 
 
 
6
3
 
 
 
8
2
6
 
 
10
3
6
 
 
12
3
44
 
 
14
10
18
1
 
16
26
11
4
12
161
7
 
1
 
180
15
6
3
2
181
29
7
18
24
182
2
2
53
54
53
Iodine Value
Number of iodine (g) absorbed by 100 g of
oil. Molecular weight and iodine number can
calculate the number of double bonds. 1 g of fat
adsorbed 1.5 g of iodine value 150.
54
Iodine Value
O
C
H
(
C
H
)
C
H
(
C
H
)
C
H
C
H
O
C
2
7
2
7
3
2
Triolein (MW 884)
O
C
H
C
H
(
C
H
)
C
H
(
C
H
)
C
O
C
H
3
2
7
2
7
A
O
C
H
C
H
(
C
H
)
C
H
(
C
H
)
C
O
C
H
3
2
7
2
7
2
Trilinolein (MW 878)
B
55
A
B
56
Iodine Value Determination
_
_
Excess unreacted ICl
(ml of Na2S2O3 volume for blank - ml of
Na2S2O3 volume for sample) ? N of
Na2S2O3 ? 0.127g/meq ? 100
Weight of Sample (g)
Iodine Value
57

• The chemical equation of iodine value
  determination shows that one double bond requires
  one I2 molecule which is 254 in molecular weight.
  100 comes from the 100 gram of sample for the
  definition of iodine number
• Iodine value defines as the number of iodine in
  grams absorbed by 100 gram of sample.

58

• Fatty acids A and B have only one double bond per
  molecule. The molecular weights of A and B are
  150 and 300, respectively. The hypothetical
  iodine value of Compound A is 150. What is the
  Iodine value of compound B?
• Triglycerides A and B have the very similar
  molecular weights of about 878. The compound A
  has 6 double bonds per molecule and has iodine
  value is 174. The compound B has 3 double bond
  per molecule. What is the iodine value of the
  compound B?

59
Brazil soybean oil has molecular weight of
900 Cuba special tropical oil has molecular
weight of 450.
Avogadros Number (N) 6.02 x 1023 / mol
60
Iodine Values of Triglycerides
Palmitoleic Acid
1
95
Oleic Acid
1
86
Linoleic Acid
2
173
Linolenic Acid
3
261
61
Compositions () of Fatty Acids of Fats
1
5
5
20
40
 
 
30
 
 
2
 
 
20
35
40
5
 
 
 
3
 
 
10
50
 
40
 
 
 
4
 
 
20
40
40
 
 
 
 
5
 
 
10
20
20
10
20
20
 
62
Number of Double bonds
Compound A and B have the same iodine values of
100. Compound A of molecular weight of 200 has
one double bond per molecule. Determine the
number of double bonds of Compound B of molecular
weight of 400.
63
Double Bond Determination
The unknown compound has molecular weight of 878
and iodine value of 173. Determine the number
of double bonds in the unknown compound
64
Determination of Double per Molecule
Iodine Value x Molecule Weight 2
x 127 x 100
Number of Double Bonds per Molecule

65
GC Analysis for Fatty Acids
1. Extract fat. 2. Saponify (hydrolysis under
basic condition). 3. Prepare methyl ester
(CH3ONa). 4. Chromatography methyl
ester. 5. Determine peak areas of fatty
acids. Fatty acids are identified by retention
time. 6. Compare with response curve of standard.
66
Triacylglycerol
O
(
C
)
H
C O
C (CH
)
CH
18
2
2
16
3
O
HC O
(C
)
C (CH
)
CH
16
2
14
3
O
H
C O
(C
)
C (CH
)
CH
2
18
2
16
3
b - palmityl distearin
67
Fatty Acids Methyl Esters
181
14
Response
183
211
24
182
20
16
18
22
Time
GC condition 10 DEGS Column (from
Supelco) Column temperature 200C.
68
Triglyceride Analysis by Liquid Chromatography
Soybean Oil Solvent CH3CN/HF Column 84346
(Waters Associates)
RESPONSE
RETENTION TIME
69
Triglycerides in Olive Oil
OL2
54 5
O2L
54 4
OPL
52 3
O3
54 3
OSL
54 3
O2P
52 2
70
Cholestrol Determination
Enzymatic Methods
R

0-Dianisidine Oxidized 0-Dianisidine (Colorle
ss) (Brown color) at 440 nm
71
Absorption Standard Curve of Cholesterol
at 440 nm
A
m
g/ml Cholesterol
72
Cholesterol Analysis by GLC
1. Prepare cholesterol butyrate. 2. Analyze by
GLC. Sensitivity - 10-7 g.
21
22
18
20
-H2O
12
19
16
17
11
13
14
15
10
1
9
2
8
3
7
6
CH3CH2CH2COOH
4
5
73
Brazil soybean oil has molecular weight of
900 Cuba special tropical oil has molecular
weight of 450.
Avogadros Number (N) 6.02 x 1023 / mol
74
Lipid Content Analysis
75

• 1. Gravimetric Method
• (1) Wet extraction - Mojonnier.
• (2) Dry extraction - Soxhlet Method.
•  
• Volumetric Methods
• (1) Babcock Method

76
Gravimetric Method

• Wet Extraction - Mojonnier.
•  For Milk
• 1) 10 g milk 1.25 ml NH4OH mix. solubilizes
  protein and neutralizes.
• 2) 10 ml CH3CH2OH - shake. Begins extraction,
  prevents gelation of proteins.
• 3) 25 ml CH3CH2OCH2CH3 - shake and mix.
• 4) 25 ml petroleum ether, mix and shake. 

77
Dry Extraction - Soxhlet Method 
Sample in thimble is continuously extracted with
ether using Soxhlet condenser. After the
extraction of fat from the sample, evaporate
ether in the flask and weigh the flask. The gain
of the weight of flask is the fat content
78
Soxhlet Method
79
Volumetric Method Babcock Method

• Theory
• Treat sample with H2SO4 or detergent.
• Centrifuge to separate fat layer.
• Measure the fat content using specially
  calibrated bottles.
• Methods
• 1. Known weight sample.
• 2. H2SO4 - digest protein, liquefy fat.
• 3. Add H2O to make fat be in graduated part of
  bottle.
• 4. Centrifuge to separate fat from other
  materials completely.

80
Analyses of Flavor Quality and Stability of Oil
81
1772 Scheele Priestley Discovered
Oxygen 1811 Avogadro Oxygen is a Diatomic
Molecule 1848 Faraday Oxygen is a
Paramagnetic Molecule 1934 Herzberg
Observation of Singlet Oxygen 1969 Foote
Wexler Rediscovered Singlet Oxygen  
               
Oxygen History
82
Molecular Orbital of Triplet Oxygen
Molecular
?
Atomic
Atomic
?
?
?
?
2Px 2Py 2Pz
2Pz 2Py 2Px
?
Energy
?
2S
2S
?
83
Valence Electrons of Triplet Oxygen
x
x
?
?
O O
?
x
x
?
?
?
x
x
Triplet oxygen
84
Pentane from Linoleic Acid by Triplet Oxygen
14
13 12 11
10 9
C
H
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
2
2
3
3
Initiation
- H

13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

Alkylradical
O
2
13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2
O
Peroxyradical
O
H


Propagation
85
13
12 11 10 9
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
4
3
O
Hydroperoxide
-
O

OH
H
13
12 11 10 9
C
H
R
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
2
2
4
3
O

Oxyradical
O

C
C
H
C
H
C
H
C
H
C
H
R
C
H
(
C
H
)
C
H

2
3
2
3
2
H
Termination

H
C
H
(
C
H
)
C
H
3
3
3
2
86
Peroxide Value
ml of Na2S2O3 ? Normality ?
1000 (milliequivalent peroxide/kg) Grams of Oil
Peroxide Value

87
Pentane from Linoleic Acid by Triplet Oxygen
14
13 12 11
10 9
C
H
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
2
2
3
3
Initiation
- H

13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

Alkylradical
O
2
13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2
O
Peroxyradical
O
H


Propagation
88
13
12 11 10 9
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
4
3
O
Hydroperoxide
-
O

OH
H
13
12 11 10 9
C
H
R
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
2
2
4
3
O

Oxyradical
O

C
C
H
C
H
C
H
C
H
C
H
R
C
H
(
C
H
)
C
H

2
3
2
3
2
H
Termination

H
C
H
(
C
H
)
C
H
3
3
3
2
89
Active Oxygen Method (AOM)
Determined the time required to obtain certain
peroxide value under specific experimental
conditions. The larger the AOM value, the better
the flavor stability of the oil.
90
Pentane from Linoleic Acid by Triplet Oxygen
14
13 12 11
10 9
C
H
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
2
2
3
3
Initiation
- H

13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

Alkylradical
O
2
13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2
O
Peroxyradical
O
H


Propagation
91
13
12 11 10 9
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
4
3
O
Hydroperoxide
-
O

OH
H
13
12 11 10 9
C
H
R
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
2
2
4
3
O

Oxyradical
O

C
C
H
C
H
C
H
C
H
C
H
R
C
H
(
C
H
)
C
H

2
3
2
3
2
H
Termination

H
C
H
(
C
H
)
C
H
3
3
3
2
92
TBA (Thiobarbituric Acid) Test  To determine the
rancidity degree of meat or fish product.

HS
N
OH
O
O

C CH
C
2
N
H
H
OH
S
OH
N
SH
N
HO

2
H
O
2
N
N
CH CH CH
OH
OH
Colored Pigment _at_532 nm
93
REACTIONS OF FATS
94
Hydrolytic Rancidity
Triglyceride Fatty acids Specially C4 butyric
acid and other short chain fatty acids in butter
are the real problem.  
Lipase
Lipase

O
C
H
O
C
(
C
H
)
C
H
2
2
2
3
O
C
H
O
C
(
C
H
)
C
H
2
4
3
O
C
H
O
C
(
C
H
)
C
H
2
2
16
3
95
Pentane from Linoleic Acid by Triplet Oxygen
14
13 12 11
10 9
C
H
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
2
2
3
3
Initiation
- H

13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

Alkylradical
O
2
13
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2
O
Peroxyradical
O
H


Propagation
96
13
12 11 10 9
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
4
3
O
Hydroperoxide
-
O

OH
H
13
12 11 10 9
C
H
R
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
2
2
4
3
O

Oxyradical
O

C
C
H
C
H
C
H
C
H
C
H
R
C
H
(
C
H
)
C
H

2
3
2
3
2
H

H
Termination
C
H
(
C
H
)
C
H
3
3
3
2
97
Malonaldehyde Formation from 3-Hexenal
O
CH3-CH2-CHCH-CH2-C
H
- H
Initiation

- OH

O

O2
O
O

O
O

CH3-CHCH
C-CH2-C
H
H
H
H
Termination
Propagation
CH3-CHCH2
Malonaldehyde