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Introduction to LipidsIntroduction to Lipids

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DefinitionDefinition

Any of a group of substances that inAny of a group of substances that ingeneral are soluble in organic solvents,general are soluble in organic solvents,

but are not soluble in water.but are not soluble in water.

The term fats and lipids used interchangeably

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1. Fatty acids

2. Neutral fats and oils

3. Waxes

4. Phospholipid

5. Sterols

6. Fat soluble vitamins

Types of Lipids

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Functions and Properties

Functions and Properties

Source of energy (9 kcal/g)

Energy reserve: any excess energy from

carbohydrate, protein and lipids are stored

as TG in adipose tissues

Provide insulation to the body from cold

Mechanical insulation: protects vital organs

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Functions and Properties

Functions and Properties

Supply Essential Fatty Acids (EFA)

Linoleic acid and linolenic acid

Helps in the formation of cell membranes

Phospholipids

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Functions and Properties

Functions and Properties

Help carry fat soluble vitamins

Flavor and taste

The satiety value

Fullness; fats are digested slower

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Fatty Acids

O

R C OH

#1 CarbonAcid Group

O

R C OH

Non-polar End - Hydrophobic End

(Fat-soluble tail)

Polar End - Hydrophilic End

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Saturated Fatty Acids

178

ctanoic Acid

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Cis 9 - Octadecenoic Acid (oleic)

Trans 9 - Octadecenoic Acid (elaidic acid)

O

C (C ) C C (C ) C O

90

O

C (C ) C C (C ) C O

Cis And Trans Fatty Acids

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Fatty Acids

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Saturated and Unsaturated Fatty AcidsSaturated and Unsaturated 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, , 11, 14 - Eicosatetraenoic

acid

Linoleic Acid

Linolenic Acid

Arachidonic Acid

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Naturally-occurring Fatty Acids

R CH2 [ 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.

n

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C4 - -

C6 - 4 9

C 16 5

C10 31 6

C12 44 0.55

C14 54 0.18

C16 63 0.08

Fatty Acids M.P.(C) mg/100 ml in H2O*

C18 70 0.04

Characteristics of Fatty Acids

* Solubility

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Effects of Double Bonds on the Melting Points

16:060

16:1 118:0 6318:1 16

18:2 -518:3 -1120:0 75

F. A. M. P. (C)

20:4 -50

M.P.

# Double bonds

x

x

xx

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FAT AND OILS

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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

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GLYCERIDES

Monoglyceride (E - monostearin) Diglyceride (EE' - distearin)

C

C

C C (C ) C

C

C

C C (C ) C

C (C ) C

Triglyceride (F - palmityl distearin)

C

C

C C (C ) C

C (C ) C

C (C ) C

( C 8)

(C )

(C 8)

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Formation of MonoglycerideFormation of Monoglyceride

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TriglyceridesTriglycerides

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Triglyceride

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FATS AND OILS

World Supply

Vegetable oil - 68%

Animal fat - 28%

Marine oil - 4%

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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

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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

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Waxes

Fatty acid + Long chain alcoholImportant in fruits:

1. Natural protective layer in fruits, vegetables, etc.

2. Added in some cases for appearance and protection.

Beeswax

O

C30 H61 O C C15H31

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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

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Fat Soluble Vitamins

Vitamin A

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Vitamin D2

Vitamin E

HO

CH 2

HH

H 3 C

H 3 C CH 3

CH 3

CH 3

2 2 2 2 2 2 2 2 2 2

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PUFAPUFA

Two or more double bonds

Members of omega 3 and omega 6 FA

(EFA) Linolenic acid omega 3 FA

Linoleic acid omega 6 FA

Richest sources of PU

FA: Vegetable oils

Corn, sunflower, cotton seed oils

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EFAEFA-- Omega

3&

6FAsOmega

3&

6FAs

Omega indicates the position of the firstdouble bond from the methyl group

The first point of unsaturation if next to thethird C= omega 3 FA

The first point of saturation if next to the

sixth C= omega 6 FA Great significance on human nutrition and

health issues