This document summarizes the key characteristics and types of lipids. Lipids are insoluble in water but soluble in non-polar solvents. The main types of lipids discussed include fatty acids, neutral fats and oils, waxes, phospholipids, sterols, and fat-soluble vitamins. Specific lipids like triglycerides, cholesterol, and various fatty acids are examined in detail. Analytical methods for analyzing lipids, such as acid value, saponification value, iodine number, gas chromatography, and enzymatic assays are also outlined.

1. LIPID
Soluble in non-polar solvents and insoluble in polar
solvents. Lipid is not polymers.
Lipids:
1. Fatty acids
2. Neutral fats and oils
3. Waxes
4. Phospholipid
5. Sterols
6. Fat soluble vitamins

2. Fatty Acids
O
R C OH
#1 Carbon
Acid Group
O
R C OH
Polar End - Hydrophilic End
Non-polar End - Hydrophobic End
(Fat-soluble tail)

3. Saturated Fatty Acids
O
8 7 6 5 4 3 2 1
CH3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 C OH
Octanoic Acid

4. Unsaturated Fatty Acids
O
8 7 6 5 4 3 2 1
CH3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 C OH
O
3 - Octenoic Acid
8 7 6 5 4 3 2 1
CH3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 C OH
3, 6 - Octadienoic Acid
Short hand: 8:1 (D3)
8:2 (D3,6)

5. Cis And Trans Fatty Acids
O
H H
CH3(CH2)7 C C (CH2)7 C OH
10 9
Cis 9 - Octadecenoic Acid (oleic)
O
H
CH3(CH2)7 C C (CH2)7 C OH
H
Trans 9 - Octadecenoic Acid (elaidic acid)

6. 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

7. Naturally-occurring fatty acids
O
R CH2 CH CH CH2 CH CH CH2 C OH
7 6 5 4 3
1. Cis form
2. Not conjugated --- isolated double bond.
3. Even numbered fatty acids.

8. CLASSIFICATION OF FATTY ACIDS PRESENT
AS GLYCERIDES IN FOOD FATS
Systematic
Name
Formula Common source
I. Saturated Fatty Acids
Common
Name
Butyric Butanoic CH3(CH2)2COOH butterfat
Caproic Hexanoic CH3(CH2)4COOH butterfat, coconut
and palm nut oils
Caprylic Octanoic CH3(CH2)6COOH coconut and palm
nut oils, butterfat
Capric Decanoic CH3(CH2)8COOH coconut and palm
nut oils, butterfat
Lauric Dodecanoic CH3(CH2)10COOH coconut and palm
nut oils, butterfat
Myristic Tetradecanoic CH3(CH2)12COOH coconut and Palm nut oil, most
animal and plant fats
Palmitic Hexadecanoic CH3(CH2)14COOH practically all animal and
plant fats
Stearic Octadecanoic CH3(CH2)16COOH animal fats and minor
component of plant fats
Arachidic Eicosanoic CH3(CH2)18COOH peanut oil

9. Common
Name
Systematic
Name
Formula Common source
II. 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
Moroctic
4,8,12,15-
Octadecatetraenoic
C17H27COOH fish oils
Arachidonic 5,8,11,14-
Eicosatetraenoic
C19H31COOH traces in animal fats

10. Common and Systematic Names of Fatty Acids
Common
Name
Systematic
Name
Formula Common source
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
Moroctic
4,8,12,15-
Octadecatetraenoic
C17H27COOH fish oils
Arachidonic 5,8,11,14-
Eicosatetraenoic
C19H31COOH traces in animal fats

11. Melting Points and Solubility in Water of Fatty Acids
Solubility in H O
Chain Length
2
Melting Point

12. CHARACTERISTICS 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
C16 63 0.08
C18 70 0.04

13. Effects of Double Bonds on the Melting Points
F. A. M. P. (0C)
16:0
60
16:1 1
18:0 63
18:1 16
18:2 -5
18:3 -11
20:0 75
20:4 -50
M.P.
# Double bonds

14. FAT AND OILS
Mostly Triglycerides:
O
H2C OH
HC OH
H2C OH
O
HO C R
O
HO C R
O
HO C R
H2C O C R
O
HC O C R
O
H2C O C R
+
+ 3 H2O
Glycerol 3 Fatty Acids

15. GLYCERIDES
H2C OH
HC OH
H2C O
O
C (CH2)16CH3
H2C O
HC OH
H2C O
O
C (CH2)16CH3
O
C (CH2)16CH3
Monoglyceride (a - monostearin) Diglyceride (a, a' - distearin)
H2C O
HC O
H2C O
O
C (CH2)16CH3
O
C (CH2)14CH3
O
C (CH2)16CH3
(C18 )
(C16 )
(C18 )
Triglyceride (b - palmityl distearin)

16. a - oleodipalmitin
1 - oleodipalmitin
Oleic
Palmitic
Palmitic
OPP
a - Linoleyldiolein
1 - Linoleyldiolein
Linoleic
Oleic
Oleic
LOO

17. FATS AND OILS ARE PRIMARILY TRIGLYCERIDES (97-99%)
Vegetable oil - world supply - 68%
Cocoa butter - solid fat
Oil seeds - liquid oil
Animal fat - 28% (from Hogs and Cattle)
Marine oil - 4%
Whale oil
cod liver oil

18. Fatty Acids (%) of Fats and Oils
Fatty Acids Butter Coconut Cottonseed Soybean
4 3
6 3
8 2 6
10 3 6
12 3 44
14 10 18 1
16 26 11 4 12
16:1 7 1
18:0 15 6 3 2
18:1 29 7 18 24
18:2 2 2 53 54
18:3 2 8

19. MELTING POINTS OF TRIGLYCERIDES
Triglyceride Melting Point (°C)
C6 -15
C12 15
C14 33
C16 45
C18 55
C18:1 (cis) -32
C18:1 (trans) 15

20. WAXES
Fatty acids + Long chain alcohol
Important in fruits:
1. Natural protective layer in fruits, vegetables, etc.
2. Added in some cases for appearance and protection.
Beeswax (myricyl palmitate), Spermaceti (cetyl palmitate)
O
C30H61 O C C15H31
O
C16H33 O C C15H31

21. PHOSPHOLIPID
Lecithin (phosphatidyl choline)
O
H2C O C R
O
O
R C O CH
CH3
+
CH3
CH3
H2C O P O CH2 CH2 N
O_
Phosphatidic Acid Choline

22. STEROLS
Male & female sex hormones
Bile acids
Vitamin D
Adrenal corticosteroids
Cholesterol
HO
H3C
21
22
H3C CH3
18
H3C
CH3
1
2
3
4
5
8
9
6 7
10
11
12
13
17 16
14 15
19
20

23. FAT SOLUBLE VITAMINS
Vitamin A:
CH2OH
CH3 CH3
H3C CH3
CH3
1
2
3
4
5
6
7
8
9

24. Vitamin D2:
Vitamin E:
HO
H3C CH3
H3C
CH2
H
H
CH3
CH3
O
R1
R2
HO
R3
CH3
CH3
(CH2CH2CH2CH2)2CH2CH2CH2CH(CH3)2

25. ANALYTICAL METHODS TO MEASURE THE
CONSTANTS OF FATS AND OILS
1. Acid Value
2. Saponification Value
3. Iodine Value
4. Gas Chromatographic Analysis for Fatty Acids
5. Liquid Chromatography
6. Cholesterol Determination

26. 1. Acid Value
Number of mgs of KOH required to neutralize the Free
Fatty Acids in 1 g of fat.
AV =
ml of KOH x N x 56
Weight of Sample
= mg of KOH

27. 2. Saponification Value
Saponification - hydrolysis of ester under alkaline
condition.
O
O
C R
O
C R
O
C R
H2C O
HC O
H2C O
+ 3 KOH
+ 3 R C OK
H2C O
H
HC O
H
H2C O
H

28. Saponification Value of Fats and Oils
Fat Saponification #
Milk Fat 210-233
Coconut Oil 250-264
Cotton Seed Oil 189-198
Soybean Oil 189-195
Lard 190-202

29. 2. 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.
5. Conduct blank determination.
SP# =
56.1(B -S) x N of HCl
Gram of Sample
B - ml of HCl required by Blank.
S - ml of HCl required by Sample.

30. 3. Iodine Number
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.

31. Iodine Value Determination
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 CH
Cl I
ICl
+
Iodine chloride
Excess unreacted ICl
ICl KI KCl
I2
I2
+
Na2S2O3 Na2S4O6 NaI
+
+ 2 + 2

32. Iodine Numbers of Triglycerides
Fatty Acids # of Double-bonds Iodine #
Palmitoleic Acid 1 95
Oleic Acid 1 86
Linoleic Acid 2 173
Linolenic Acid 3 261
Arachidonic Acid 4 320

33. Compositions (%) of Fatty Acids of Fats
Fat C4 C6 C10 C16 C18 C18:1 C18:2 C18:3 C20:4
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
6 100

34. 4. 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.

35. Fatty Acids Methyl Esters:
14
18:1
18:2 20
18:3
22
21:1 24
16
18
Time
Response
GC condition: 10% DEGS Column (from supelco)
Column temperature 200C.

36. 5. TRIGLYCERIDE ANALYSIS BY LIQUID
CHROMATOGRAPHY
Soybean Oil
Solvent CH3CN/HF
Column 84346 (Waters Associates)
RESPONSE
RETENTION TIME

37. Oleate-containing triglycerides in olive oil
Fatty Acid
Composition
Total Acyl Carbons:
Unsaturation
Equivalent Carbon
Number
OL2 54:5 44
O2L 54:4 46
OPL 52:3 46
O3 54:3 48
OSL 54:3 48
O2P 52:2 48
O2S 54:2 50
OPS 52:1 50
OS2 54:1 52

38. 6. CHOLESTEROL DETERMINATION
Enzymatic Determination: Cholesterol Oxidase
HO O
H2O2
Choles terol Oxidase
etc. +
H2O2
CH3O OCH3
CH3O OCH3
+ Peroxidase + H2O
H2N NH2 HN NH
0-Dianisidine Oxidized 0-Dianisidine
(Colorless) (Brown color)At 440 nm

39. Cholesterol by GLC
1. Prepare cholesterol butyrate.
2. Analyze by GLC.
time in GC - 15 min.
sensitivity - 10-7 g.
g/ml Cholesterol
Absorption
at 440 nm

40. Spectromertic Absorption Standard Curve of Cholesterol
Cholesterol by GLC
1. Prepare cholesterol butyrate.
2. Analyze by GLC.
time in GC - 15 min.
sensitivity - 10-7 g.
g/ml Cholesterol
Absorption
at 440 nm

41. LIPID CONTENT ANALYSES
1. Gravimetric Method
(1) Wet extraction - Roese Gottliegb & Mojonnier.
(2) Dry extraction - Soxhlet Method.
2. Volumetric Methods (Babcock, Gerber Methods)

42. 1. Gravimetric Method
(1) Wet Extraction - Roese Gottlieb & Mojonnier.
For Milk:
1) 10 g milk + 1.25 ml NH4OH mix. solubilizes
protein and neutralizes.
2) + 10 ml EtOH - shake. Begins extraction, prevents
gelation of proteins.
3) + 25 ml Et2O - shake and mix.
4) + 25 ml petroleum ether, mix and shake.

43. (2) Dry Extraction - Soxhlet Method.
Sample in thimble is continuously extracted with ether
using Soxhlet condenser. After extraction, direct
measurement of fat
- evaporate ether and weigh the flask.
Indirect measurement - dry thimble and weigh thimble and
sample.

44. Soxhlet Method.

45. 2. Volumetric Method (Babcock, Gerber Methods)
Theory:
1. Treat sample with H2SO4 or detergent.
2. Centrifuge to separate fat layer.
3. Measure the fat content using specially calibrated bottles.
Methods:
1. Known weight sample.
2. H2SO4 - digest protein, liquefy fat.
3. Add H2O so that fat will be in graduated part of bottle.
4. centrifuge to separate fat from other materials completely.

46. REACTIONS OF FATS
Hydrolytic Rancidity:
1. Triglyceride -> Fatty acids
Specially C4 butyric acid (or other short chain fatty
acids) are the real problem.
2. By lipase.

47. LIPID OXIDATION
Major flavor problems in food during storage are mainly
due to the oxidation of lipid.
Lipid Oxidation - free radical reactions.
1. Initiation.
2. Propagation.
3. Termination.

48. Pentane Formation from Linolenic Acid
14 13 12 11 10 9
CH3 (CH2)3 CH2 CH CH CH2 CH CH CH2 COOH
- .
12 11 10 9
CH3 (CH2)3 CH2 CH CH CH CH CH CH2 COOH
+
12 11 10 9
12 11 10 9
CH3 (CH2)3 CH2 CH CH CH CH CH CH2 COOH
+
_
+ .
12 11 10 9
12 11 10 9
+
O
O
.
H
.
CH3 (CH2)3 CH2 CH CH CH CH CH CH2 COOH
O
O
H
CH3 (CH2)3 CH2 CH CH CH CH CH CH2 COOH
O
Initiation (metal)
Propagation
Propagation
.
O2
H
OH .
Hydroperoxide
Decomposition
O
CH3 (CH2)3 CH2 H C CH CH CH CH C2H COOH
CH3 (CH2)3 CH3
.
H Termination .
Pentane
n
n
n
- n
n
n

49. ANALYSIS OF FLAVOR QUALITY & STABILITY OF OIL
1. Peroxide Value
O O
KI CH3 C OH HI CH3 C OK
ROOH HI I2 H2O ROH
I2 Na2S2O3 NaI Na2S4O6
A.
B.
C.
+
+
+
+
+
+
+
2
2
2
Peroxide Value = ml of Na2S2O3  N  1000
(milliequivalent peroxide/kg of sample) Grams of Oil

50. 2. 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.

51. 3. TBA Test.
To determine the rancidity degree of meat or fish product.
N
N
HS
OH
OH
C CH2 C
O
O
H
H
OH
OH
HS
N
N
OH
SH
N
N
HO
+
CH CH CH
H2O
Colored Pigment
+ 2