lipid more than sufficient

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

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

Saturated Fatty Acids CH3 CH2 CH2 CH2 CH2 CH2 CH2 C OH

O1245678 3

Octanoic Acid

Unsaturated Fatty Acids CH3 CH2 CH2 CH2 CH2 CH2 CH2 C OH

O1245678 3

CH3 CH2 CH2 CH2 CH2 CH2 CH2 C OH

O1245678 3

3 - Octenoic Acid

3, 6 - Octadienoic Acid

Short hand: 8:1 (3)

8:2 (3,6)

Cis 9 - Octadecenoic Acid (oleic)

Trans 9 - Octadecenoic Acid (elaidic acid)

O

CH3(CH2)7 C C (CH2)7 C OH

HH

910 O

CH3(CH2)7 C C (CH2)7 C OH

H

H

Cis And Trans Fatty Acids

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

Naturally-occurring fatty acids R CH2 CH CH CH2 CH CH CH2 C OH

O

7 6 5 4 3

1. Cis form

2. Not conjugated --- isolated double bond.

3. Even numbered fatty acids.

CLASSIFICATION OF FATTY ACIDS PRESENT AS GLYCERIDES IN FOOD FATS

I. Saturated Fatty Acids

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

Common Name

Systematic Name

Formula Common source

Common Name

Systematic Name


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

oilsEleostearic 9,11,13-Octadecatrienoic C17H29COOH peanut seed fats

D. Tetraethenoid Acids

Moroctic4,8,12,15-Octadecatetraenoic

C17H27COOH fish oils

Arachidonic 5,8,11,14-Eicosatetraenoic

C19H31COOH traces in animal fats

Common and Systematic Names of Fatty AcidsCommon and Systematic Names of Fatty Acids

Common Name

Systematic Name


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

oilsEleostearic 9,11,13-Octadecatrienoic C17H29COOH peanut seed fats

D. Tetraethenoid Acids

Moroctic4,8,12,15-Octadecatetraenoic

C17H27COOH fish oils

Arachidonic 5,8,11,14-Eicosatetraenoic

C19H31COOH traces in animal fats

Melting Points and Solubility in Water of Fatty Acids

Solubility in H O

Chain Length

2

Melting Point

C4 - 8 -

C6 - 4 970

C8 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

Effects of Double Bonds on the Melting Points

16:0

6016:1 118:0 6318:1 1618:2 -518:3 -1120:0 75

F. A. M. P. (0C)

20:4 -50

M.P.

# Double bonds

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 RO

O

H2C O C R

HC O C R+ + 3 H2O

Glycerol 3 Fatty Acids

GLYCERIDES

Monoglyceride ( - monostearin) Diglyceride (' - distearin)

H2C OH

HC OH

H2C O

O

C (CH2)16CH3

H2C O

HC OH

H2C O

O

C (CH2)16CH3

C (CH2)16CH3

O

Triglyceride ( - palmityl distearin)

H2C O

HC O

H2C O

O

C (CH2)16CH3

C (CH2)16CH3

O

O

C (CH2)14CH3

( C18)

(C16)

(C18)

- oleodipalmitin

1 - oleodipalmitin

Oleic

Palmitic

Palmitic

OPP

- Linoleyldiolein

1 - Linoleyldiolein

Oleic

Linoleic

OleicLOO

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

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

16:1 7 1

18:0 15 6 3 2

18:1 29 7 18 24

18:2 2 2 53 54

Fatty Acids Butter Coconut Cottonseed Soybean

18:3 2 8

MELTING POINTS OF TRIGLYCERIDES

C6 -15

C12 15

C14 33

C16 45

C18 55

C18:1 (cis) -32

Triglyceride Melting Point (°C)

C18:1 (trans) 15

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

PHOSPHOLIPID

Lecithin (phosphatidyl choline) O

O

H2C O C RO

R C O CH

H2C O P O CH2 CH2 N+ CH3

CH3

CH3

O_

Phosphatidic Acid Choline

STEROLS

Male & female sex hormones

Bile acids

Vitamin D

Adrenal corticosteroids

Cholesterol HO

H3C

H3C

H3C CH3

CH3

123 4 5

6 789

10

1112

1314 15

1617

18

21 22

19

20

FAT SOLUBLE VITAMINS

Vitamin A: CH2OH

CH3 CH3

CH3

CH3H3C

12

34

5

67

89

Vitamin D2:

Vitamin E:

HO

CH2

HH

H3C

H3C CH3

CH3

CH3 O

R1

R2

HO

R3

CH3(CH2CH2CH2CH2)2CH2CH2CH2CH(CH3)2

CH3

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

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 56Weight of Sample

= mg of KOH

2. Saponification Value

Saponification - hydrolysis of ester under alkaline condition.

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

Milk Fat 210-233

Coconut Oil 250-264

Cotton Seed Oil 189-198

Soybean Oil 189-195

Fat

Saponification #

Lard 190-202

Saponification Value of Fats and Oils

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.

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

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.

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

+ ICl KI KCl

I2

I2

Na2S2O3 Na2S4O6 NaI

+

+ 2 2+

+

Excess unreacted ICl

Iodine Value Determination

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

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

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.

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.

5. TRIGLYCERIDE ANALYSIS BY LIQUID CHROMATOGRAPHY

Soybean Oil

Solvent CH3CN/HF

Column 84346 (Waters Associates)

RESPONSE

RETENTION TIME

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 Acid Composition

Total Acyl Carbons: Unsaturation

Equivalent Carbon Number

OS2 54:1 52

6. CHOLESTEROL DETERMINATION

Enzymatic Determination: Cholesterol Oxidase HO O

H2O2

Cholesterol Oxidaseetc. +

H2O2

CH3O OCH3

H2N NH2 HN NH

OCH3CH3O

H2OPeroxidase+ +

0-Dianisidine Oxidized 0-Dianisidine

(Colorless) (Brown color)At 440 nm

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

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

Absorption at 440 nm

LIPID CONTENT ANALYSES

1. Gravimetric Method

(1) Wet extraction - Roese Gottliegb & Mojonnier.

(2) Dry extraction - Soxhlet Method.

2. Volumetric Methods (Babcock, Gerber Methods)

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.

(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.

Soxhlet Method.

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.

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.

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.

Pentane Formation from Linolenic Acid +

+

_

.+

.-

+

CH3 (CH2)3 CH2 CH CH CH CH CH CH2 COOH

CH3 (CH2)3 CH2 CH CH CH2 CH CH CH2 COOH

.

H

.


O

O

H

O

O



O

Initiation (metal)

Propagation

Propagation.

O2

H

OH.HydroperoxideDecomposition

CH3 (CH2)3 CH2 H C CH CH CH CH CH2 COOH

CH3 (CH2)3 CH3

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

ANALYSIS OF FLAVOR QUALITY & STABILITY OF OIL

1. Peroxide Value

KI CH3 C OH HI CH3 C OK

O O

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

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.

3. TBA Test.

To determine the rancidity degree of meat or fish product. N

N

HS

OH

OH

C CH2 C

O

H

O

H

OH

OH

HS

N

N

OH

SH

N

N

CH CH CH

HO

H2O

Colored Pigment

+

+ 2

lipid more than sufficient

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