Lipid Structure

 

 

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

Example:

Octanoic Acid

Unsaturated Fatty Acids

3 - Octenoic Acid

3, 6 - Octadienoic Acid

Short hand: 8:1 (D3)

8:2 (D3,6)

Cis

Cis 9 - Octadecenoic Acid (oleic)

Trans

Trans 9 - Octadecenoic Acid (elaidic acid)

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 are:

1. Cis form

2. Not conjugated --- isolated double bond.

3. Even numbered fatty acids.

 

 

CLASSIFICATION OF FATTY ACIDS PRESENT AS GLYCERIDES IN FOOD FATS

Common Name

Systematic Name

Formula

Common source

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

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

Fatty Acids

 

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

 

 

 

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

 

 

 

 

 

 

 

 

 

 

 

 

FAT AND OILS

 

Mostly Triglycerides:

Glycerol 3 Fatty Acids

 

GLYCERIDES

Monoglyceride (a - monostearin)

Diglyceride (a, a' - distearin)

 

Triglyceride (b - palmityl distearin)

a - oleodipalmitin

1 - oleodipalmitin

 

a - Linoleyldiolein

1 - Linoleyldiolein

 

FATS AND OILS ARE PRIMARILY TRIGLYCERIDES (97-99%)

Fats & Oils

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

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

 

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

 

 

 

 

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)

 

 

 

PHOSPHOLIPID

Lecithin (phosphatidyl choline)

 

 

 

 

STEROLS

Male & female sex hormones

Bile acids

Vitamin D

Adrenal corticosteroids

Cholesterol

 

 

 

FAT SOLUBLE VITAMINS

Vitamin A:

 

 

Vitamin D2:

 

 

Vitamin E:

 

Vitamin K1: