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LIPID - PowerPoint PPT Presentation


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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. Waxes 4. Phospholipid 5. Sterols 6. Fat soluble vitamins. Fatty Acids . Saturated Fatty Acids. Octanoic Acid . Unsaturated Fatty Acids .

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slide1

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

slide3

Saturated Fatty Acids

Octanoic Acid

slide4

Unsaturated Fatty Acids

3 - Octenoic Acid

3, 6 - Octadienoic Acid

Short hand: 8:1 (D3)

8:2 (D3,6)

slide5

Cis And Trans Fatty Acids

Cis 9 - Octadecenoic Acid (oleic)

Trans 9 - Octadecenoic Acid (elaidic acid)

slide6

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

slide7

Naturally-occurring fatty acids

1. Cis form

2. Not conjugated --- isolated double bond.

3. Even numbered fatty acids.

slide8

Common Name

Systematic Name

Formula

Common source

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

slide9

Common Name

Systematic Name

Formula

Common source

Arachidonic

5,8,11,14-Eicosatetraenoic

C19H31COOH

traces in animal fats

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

4,8,12,15-Octadecatetraenoic

Moroctic

C17H27COOH

fish oils

common and systematic names of fatty acids

Common Name

Systematic Name

Formula

Common source

Arachidonic

5,8,11,14-Eicosatetraenoic

C19H31COOH

traces in animal fats

Common and Systematic Names of 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

slide12

Fatty Acids

M.P.(0C)

mg/100 ml Soluble in H2O

C18

70

0.04

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

slide13

F. A.

M. P. (0C)

60

16:0

16:1

1

18:0

63

18:1

16

18:2

-5

18:3

-11

20:0

75

20:4

-50

Effects of Double Bonds on the Melting Points

slide14

FAT AND OILS

Mostly Triglycerides:

Glycerol 3 Fatty Acids

slide15

GLYCERIDES

Monoglyceride (a - monostearin) Diglyceride (a, a' - distearin)

Triglyceride (b - palmityl distearin)

slide16

a - oleodipalmitin

1 - oleodipalmitin

a - Linoleyldiolein

1 - Linoleyldiolein

slide17

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

slide18

Fatty Acids

Butter

Coconut

Cottonseed

Soybean

18:3

2

8

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

slide19

Triglyceride

Melting Point (°C)

C6

-15

C12

15

C14

33

C16

45

C18

55

C18:1 (cis)

-32

C18:1 (trans)

15

MELTING POINTS OF TRIGLYCERIDES

slide20

WAXES

  • Fatty acids + 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)
slide21

PHOSPHOLIPID

Lecithin (phosphatidyl choline)

slide22

STEROLS

Male & female sex hormones

Bile acids

Vitamin D

Adrenal corticosteroids

Cholesterol

slide24

Vitamin D2:

Vitamin E:

slide25

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

slide26

1. Acid Value

Number of mgs of KOH required to neutralize the Free Fatty Acids in 1 g of fat.

slide27

2. Saponification Value

Saponification - hydrolysis of ester under alkaline condition.

slide28

Fat

Saponification #

Lard

190-202

Saponification Value of Fats and Oils

Milk Fat

210-233

Coconut Oil

250-264

Cotton Seed Oil

189-198

Soybean Oil

189-195

slide29

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.
  • Conduct blank determination.
  • B - ml of HCl required by Blank.
  • S - ml of HCl required by Sample.
slide30

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.

slide31

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)

Excess unreacted ICl

slide32

Fatty Acids

# of Double-bonds

Iodine #

Arachidonic Acid

4

320

Iodine Numbers of Triglycerides

Palmitoleic Acid

1

95

Oleic Acid

1

86

Linoleic Acid

2

173

Linolenic Acid

3

261

slide33

Fat

C4

C6

C10

C16

C18

C18:1

C18:2

C18:3

C20:4

6

100

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

slide34

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.

slide35

Fatty Acids Methyl Esters:

GC condition: 10% DEGS Column (from supelco)

Column temperature 200C.

slide36

5. TRIGLYCERIDE ANALYSIS BY LIQUID CHROMATOGRAPHY

Soybean Oil

Solvent CH3CN/HF

Column 84346 (Waters Associates)

slide37

Fatty Acid

Composition

Total Acyl Carbons: Unsaturation

Equivalent Carbon Number

OS2

54:1

52

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

slide38

6. CHOLESTEROL DETERMINATION

Enzymatic Determination: Cholesterol Oxidase

0-Dianisidine Oxidized 0-Dianisidine

(Colorless) (Brown color)At 440 nm

slide39

Cholesterol by GLC

1. Prepare cholesterol butyrate.

2. Analyze by GLC.

time in GC - 15 min.

sensitivity - 10-7 g.

spectromertic absorption standard curve of cholesterol
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.

slide41

LIPID CONTENT ANALYSES

1. Gravimetric Method

(1) Wet extraction - Roese Gottliegb & Mojonnier.

(2) Dry extraction - Soxhlet Method.

2. Volumetric Methods (Babcock, Gerber Methods)

slide42

1. Gravimetric Method

  • 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
(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.

slide45

2. Volumetric Method (Babcock, Gerber Methods)

  • 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 so that fat will be in graduated part of bottle.
  • 4. centrifuge to separate fat from other materials completely.
slide46

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.

slide47

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.

slide49

ANALYSIS OF FLAVOR QUALITY & STABILITY OF OIL

1. Peroxide Value

Peroxide Value = ml of Na2S2O3  N  1000

(milliequivalent peroxide/kg of sample) Grams of Oil

slide50

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.

slide51

3. TBA Test.

 To determine the rancidity degree of meat or fish product.