Holem Hashm Rasul

Collage Agriculture / Department of Food Sciences

October /2014

Food Lipids

Lipids Lipids

Lipids are biological molecules that are insoluble in Lipids are biological molecules that are insoluble in

water but soluble in nonpolar solvents.water but soluble in nonpolar solvents.

Types of LipidsTypes of Lipids

1.Fats and oils (Triglycerides)1.Fats and oils (Triglycerides)

2.Phospholipids2.Phospholipids

3. Steroids as they do not contain fatty 3. Steroids as they do not contain fatty acidsacids

Fats & Oils Triglycerides – Fats & Oils Triglycerides –

1. Predominate form of fat in foods1. Predominate form of fat in foods

and major storage form of fat in the bodyand major storage form of fat in the body, , also called triacylglycerols.also called triacylglycerols.

2. Esters of glycerol.2. Esters of glycerol.

3. Produced by esterification.3. Produced by esterification.

4. Formed when the hydroxyl groups of 4. Formed when the hydroxyl groups of glycerol react with the carboxyl groups of glycerol react with the carboxyl groups of fatty acids.fatty acids.

Triglycerides – Fats & OilsTriglycerides – Fats & Oils

HH

H C-OHH C-OH

H C-OHH C-OH

H C-OHH C-OH

H H

Fatty AcidFatty Acid

Fatty Acid Fatty Acid

Fatty Acid

Fatty Acid

Glycerol Monoglyceride Diglyceride TriglycerideGlycerol Monoglyceride Diglyceride Triglyceride

Structure of TriglycerideStructure of Triglyceride

OHCH2

OH

OHCH2

CHO

(CH2)14CH3CHO

O

(CH2)14CH3CHO

O

(CH2)14CH3CHO

glycerol + 3 fatty acids → triglyceride + H2O

O

O

C (CH2)14CH3

CH O

O

C (CH2)14CH3

CH2 O

O

C (CH2)14CH3

CH2

→

+ 3H2O

1.1. HydrogenationHydrogenation Unsaturated compounds rUnsaturated compounds react with Heact with H22

CC=C bonds =C bonds C–CC–C bondsbonds

2. 2. HydrolysisHydrolysis Split by water and acid or enzyme catalystSplit by water and acid or enzyme catalyst Produce glycerol and 3 fatty acidsProduce glycerol and 3 fatty acids

Properties of TriglyceridesProperties of Triglycerides

1.1. Energy storageEnergy storage

2.2. Physical & thermal insulatorPhysical & thermal insulator

3.3. Carrier of fat soluble vitaminsCarrier of fat soluble vitamins

Functions of TriglyceridesFunctions of Triglycerides

Fatty AcidsFatty Acids

1.1. long-chain carboxylic acids.long-chain carboxylic acids.

2.2. Typically contain 12-18 carbon Typically contain 12-18 carbon atoms.atoms.

3.3. insoluble in water.insoluble in water.

4.4. Can be saturated or unsaturated.Can be saturated or unsaturated.

5.5. Some contain double bondsSome contain double bonds

Copyright © 2007 by Pearson Education, Inc.Publishing as Benjamin Cummings

Properties of SaturatedProperties of SaturatedFatty AcidsFatty Acids

1. Saturated = C–C bonds

2. Closely packed

3. Strong attractions between chains

4. High melting points

5. Solids at room temperature

COOHCOOHCOOH

Properties of UnsaturatedProperties of UnsaturatedFatty AcidsFatty Acids

1.1. Contain one or more double CContain one or more double C=C bonds=C bonds

2.2. Nonlinear chains do not allow molecules to pack Nonlinear chains do not allow molecules to pack closelyclosely

3.3. Few interactions between chains.Few interactions between chains.

4.4. Low melting points.Low melting points.

5.5. Liquids at room temperature.Liquids at room temperature.6.6. Cis double bonds.Cis double bonds.

C CH H

COOHcis double bond

© 2002 Wadsworth Publishing / Thomson Learning™

Peanuts

PhospholipidsPhospholipids

1. similar to triglycerides in structure except only 2 fatty acids + choline

2. Structure with two distinct parts-Fat soluble part.-Water soluble part (phosphate + N-compound)

3. Phospholipids in foods: Lecithin, egg yolks, soybeans, wheat germ, peanuts

Functions of PhospholipidsFunctions of Phospholipids

1. Cell membrane structure1. Cell membrane structure

2. Emulsifier 2. Emulsifier

(helps keep fats in solution)(helps keep fats in solution)

- Fat digestion- Fat digestion

- Fat transport in blood- Fat transport in blood

SterolsSterols

Structure Consists of Carbon Rings

Sterols (Sterols (Cholesterol)Cholesterol)

Cholesterol is a sterols – in foods andCholesterol is a sterols – in foods and

made by the liver; dietary sources made by the liver; dietary sources include egg yolks, liver, meats, dairy include egg yolks, liver, meats, dairy productsproducts

Functions of CholesterolFunctions of Cholesterol

1.1. Cell membrane structureCell membrane structure2.2. Precurser for:Precurser for:

-Bile acids-Bile acids-Steroid hormones-Steroid hormones-Vitamin D-Vitamin D

3.3. Sources: Sources: -Animal fats only-Animal fats only-Made in liver (non-dietary essential)-Made in liver (non-dietary essential)

Thank You

Thank You