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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. Waxes4. Phospholipid
5. Sterols
6. Fat soluble vitamins
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Fatty Acids
O
R C OH
#1 Carbon Acid Group
O
R C OH
Non-polar End - Hydrophobic End(Fat-soluble tail)
Polar End - Hydrophilic End
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Saturated Fatty Acids
CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 C OH
O1245678 3
Octanoic Acid
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Unsaturated Fatty Acids
CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 C OHO1245678 3
CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 C OHO
1245678 3
3 - Octenoic Acid
3, 6 - Octadienoic Acid
Short hand: 8:1 ( 3)
8:2 ( 3,6)
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Cis 9 - Octadecenoic Acid (oleic)
Trans 9 - Octadecenoic Acid (elaidic acid)
O
CH 3(CH 2)7 C C (CH 2)7 C OH
HH
910
O
CH 3(CH 2)7 C C (CH 2)7 C OHH
H
Cis And Trans Fatty Acids
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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 - Eicosatetraenoicacid
Linoleic Acid
Linolenic Acid
Arachidonic Acid
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Naturally-occurring fatty acids
R CH 2 CH CH CH 2 CH CH CH 2 C OH
O
7 6 5 4 3
1. Cis form
2. Not conjugated --- isolated double bond.
3. Even numbered fatty acids.
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CLASSIFICATION OF FATTY ACIDS PRESENTAS GLYCERIDES IN FOOD FATS
I. Saturated Fatty Acids
Butyric Butanoic CH3(CH2)2COOH butterfat
Caproic Hexanoic CH3(CH2)4COOH butterfat, coconutand palm nut oils
Caprylic Octanoic CH3(CH2)6COOH coconut and palmnut oils, butterfat
Capric Decanoic CH3(CH2)8COOH coconut and palmnut oils, butterfat
Lauric Dodecanoic CH3(CH2)10COOH coconut and palmnut oils, butterfatMyristic Tetradecanoic CH3(CH2)12COOH coconut and Palm nut oil, most
animal and plant fatsPalmitic Hexadecanoic CH3(CH2)14COOH practically all animal and
plant fatsStearic Octadecanoic CH3(CH2)16COOH animal fats and minor
component of plant fatsArachidic Eicosanoic CH3(CH2)18COOH peanut oil
CommonName
SystematicName
Formula Common source
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CommonName
SystematicName
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, andcottonseed oils
C. Triethenoid Acids Linolenic 9,12,15-Octadecatrienoic C17H29COOH linseed and other seed
oilsEleostearic 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- C19H31COOH traces in animal fats
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Common and Systematic Names of Fatty AcidsCommon and Systematic Names of Fatty Acids
CommonName
SystematicName
Formula Common source
A. Monoethenoic Acids
Oleic Cis 9-octadecenoic C17H33COOH plant and animal fats
Elaidic Trans 9-Octadecenoic C17H33COOH animal fats
B. Diethenoic AcidsLinoleic 9,12-Octadecadienoic C17H31COOH peanut, linseed, and
cottonseed oils C. Triethenoid Acids Linolenic 9,12,15-Octadecatrienoic C17H29COOH linseed and other seed
oilsEleostearic 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
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C4 - 8 -
C6 - 4 970C8 16 75
C10 31 6
C12 44 0.55
C14 54 0.18
C16 63 0.08
Fatty Acids M.P.(0C) mg/100 ml Soluble in H2O
C18 70 0.04
CHARACTERISTICS OF FATTY ACIDS
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Effects of Double Bonds on the Melting Points
16:0 6016:1 118:0 6318:1 16
18:2 -518:3 -1120:0 75
F. A. M. P. (0C)
20:4 -50
M.P.
# Double bonds
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FAT AND OILS
Mostly Triglycerides:
O
H2C OH
HC OH
H2C OH
HO C R
HO C R
HO C R
O
O
O
H2C O C R O
OH2C O C R
HC O C R + + 3 H 2O
Glycerol 3 Fatty Acids
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GLYCERIDES
Monoglyceride ( - monostearin) Diglyceride ( , ' - distearin)
H2C OH
HC OH
H2C O
O
C (CH 2)16 CH 3
H2C O
HC OH
H2C OO
C (CH 2)16 CH 3
C (CH 2)16 CH 3
O
Triglyceride ( - palmityl distearin)
H2C O
HC O
H2C O
O
C (CH 2)16 CH 3
C (CH 2)16 CH 3
O
O
C (CH 2)14 CH 3
( C18 )
(C16 )
(C18 )
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- oleodipalmitin
1 - oleodipalmitin
Oleic
PalmiticPalmitic
OPP
- Linoleyldiolein
1 - Linoleyldiolein
Oleic
Linoleic
Oleic LOO
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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
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Fatty Acids (%) of Fats and Oils
4 36 38 2 6
10 3 612 3 4414 10 18 116 26 11 4 12
16:1 7 118:0 15 6 3 218:1 29 7 18 2418:2 2 2 53 54
Fatty Acids Butter Coconut Cottonseed Soybean
18:3 2 8
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MELTING POINTS OF TRIGLYCERIDES
C6 -15
C12 15
C14 33
C16 45
C18 55C18:1 (cis) -32
Triglyceride Melting Point (C)
C18:1 (trans) 15
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WAXES Fatty acids + Long chain alcohol
Important in fruits:
3. Natural protective layer in fruits, vegetables, etc.
4. Added in some cases for appearance and protection.
Beeswax (myricyl palmitate), Spermaceti (cetyl palmitate)
O
C30 H61 O C C 15 H31
OC16 H33 O C C 15 H31
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PHOSPHOLIPID
Lecithin (phosphatidyl choline)
O
O
H2C O C R O
R C O CH
H2C O P O CH 2 CH 2 N+
CH 3CH 3
CH 3
O_
Phosphatidic Acid Choline
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STEROLS
Male & female sex hormones
Bile acids
Vitamin D
Adrenal corticosteroids
Cholesterol
HO
H 3 C
H 3 C
H 3 C CH 3
CH 3
123 4 5
6 789
1011
1213
14 15
1617
18
21 22
19
20
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FAT SOLUBLE VITAMINS
Vitamin A:
CH2 OHCH3 CH3
CH3
CH 3H3C
12
34
5
67
89
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Vitamin D2:
Vitamin E:
HO
CH 2
HH
H 3 C
H 3 C CH 3
CH 3
CH 3
OR
1
R 2
HO
R 3
CH 3(CH 2CH 2CH 2CH 2)2CH 2CH 2CH 2CH(CH 3)2
CH 3
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ANALYTICAL METHODS TO MEASURE THECONSTANTS OF FATS AND OILS
1. Acid Value
2. Saponification Value3. Iodine Value
4. Gas Chromatographic Analysis for Fatty Acids
5. Liquid Chromatography
6. Cholesterol Determination
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1. Acid Value
Number of mgs of KOH required to neutralize the FreeFatty Acids in 1 g of fat.
AV =ml of KOH x N x 56Weight of Sample
= mg of KO
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2. Saponification Value
Saponification - hydrolysis of ester under alkalinecondition.
O
C R
O
O
C R
C R O
H2C O
HC O
H2C O
KOH
H
H
H
H2C O
HC O
H2C O
R C OK + 3 + 3
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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.
6. Conduct blank determination.
B - ml of HCl required by Blank.
S - ml of HCl required by Sample.
SP# =56.1(B -S) x N of HCl
Gram of Sample
2. Saponification Value Determination
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Iodine Value = (ml of Na 2S2O3 volume for blank - ml of Na 2S2O3 volume for sample) N of Na 2S2O3 0.127g/meq 100
Weight of Sample (g)
CH CH CH CHCl I
ICl
Iodine chloride
+
ICl KI KCl
I 2
I 2
Na 2 S 2 O 3 Na 2 S 4 O 6 NaI
+
+ 2 2+
+Excess unreacted ICl
Iodine Value Determination
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Iodine Numbers of Triglycerides
Palmitoleic Acid 1 95
Oleic Acid 1 86
Linoleic Acid 2 173
Linolenic Acid 3 261
Fatty Acids # of Double-bonds Iodine #
Arachidonic Acid 4 320
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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
Fat C4 C6 C10 C16 C18 C18:1 C18:2 C18:3 C20:4
6 100
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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.
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Fatty Acids Methyl Esters:
14
18:1
18:2 2018:3
22
21:1 2416 18
Time
Response
GC condition: 10% DEGS Column (from supelco)
Column temperature 200C.
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5. TRIGLYCERIDE ANALYSIS BY LIQUIDCHROMATOGRAPHY
Soybean Oil
Solvent CH 3CN/HF
Column 84346 (Waters Associates)
RESPONSE
RETENTION TIME
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Oleate-containing triglycerides in olive oil
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
Fatty AcidComposition
Total Acyl Carbons:Unsaturation
Equivalent Carbon Number
OS2 54:1 52
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6. CHOLESTEROL DETERMINATION
Enzymatic Determination: Cholesterol Oxidase
HO OH2O2
Cholesterol Oxidase
etc. +
H2O2
CH3O OCH3
H2 N NH2 HN NH
OCH3CH3O
H2OPeroxidas e+ +
0-Dianisidine Oxidized 0-Dianisidine
(Colorless) (Brown color)At 440 nm
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Spectromertic Absorption Standard Curve of CholesterolSpectromertic 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
Absorptionat 440 nm
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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.
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(2) Dry Extraction - Soxhlet Method .
Sample in thimble is continuously extracted with ether
using Soxhlet condenser. After extraction, directmeasurement of fat
- evaporate ether and weigh the flask.
Indirect measurement - dry thimble and weigh thimble andsample.
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Soxhlet Method .
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2. Volumetric Method (Babcock, Gerber Methods)
Theory:
2. Treat sample with H2SO4 or detergent.
3. Centrifuge to separate fat layer.
4. 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.
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REACTIONS OF FATS
Hydrolytic Rancidity:
1. Triglyceride -> Fatty acidsSpecially C4 butyric acid (or other short chain fattyacids) are the real problem.
2. By lipase.
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P F i f Li l i A id
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Pentane Formation from Linolenic Acid
+
+
_
.+
.-
+
CH 3 (CH 2)3 CH 2 CH CH CH CH CH CH 2 COOH
CH 3 (CH 2)3 CH 2 CH CH CH 2 CH CH CH 2 COOH
.
H
.
CH 3 (CH 2)3 CH 2 CH CH CH CH CH CH 2 COOH
O
O
H
O
O
CH 3 (CH 2)3 CH 2 CH CH CH CH CH CH 2 COOH
CH 3 (CH 2)3 CH 2 CH CH CH CH CH CH 2 COOH
O
Initiation (metal)
Propagation
Propagation.
O2
H
OH.HydroperoxideDecomposition
CH 3 (CH 2)3 CH 2 H C CH CH CH CH CH 2 COOH
CH 3 (CH 2)3 CH 3
O.
H.Termination
Pentane
14 13 12 11 10 9
12 11 10 9
12 11 10 9
12 11 10 9
12 11 10 9
12 11 10 9
n
n
n
- n
n
n
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ANALYSIS OF FLAVOR QUALITY & STABILITY OF OIL
1. Peroxide Value
KI CH 3 C OH HI CH 3 C OK
O O
ROOH HI I 2 H 2 O ROH
I 2 Na 2 S 2 O 3 NaI Na2 S 4 O 6
A.
B.
C.
+
+
+
+
+
+
+
2
2
2
Peroxide Value = ml of Na2S2O3 N 1000
(milliequivalent peroxide/kg of sample) Grams of Oil
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3. TBA Test.
To determine the rancidity degree of meat or fish product.
N
N
HS
OH
OH
C CH 2 C
O
H
O
H
OH
OH
HS
N
N
OH
SH
N
N
CH CH CH
HO
H 2O
Colored Pigment
+
+ 2
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