presentation chemistry option

FATS AND LIPID

PRESENTED BY:NABILAHANIS FATIN

1. Fat and oil is actually natural esters which occur in the tissue of living organism.

2. Oil and fat are all tri-ester of propan-1, 2, 3-triol (glycerol) with carboxylic acid which having a long hydrocarbon chain

3. There are 3 type of lipid that is found in the human body: – Triglycerides (fat and oil)– Phospholipids (lecithin)– Steroids (cholesterol

4. Chemically fat and oils are similar but it differ to each other due to the state In Room Temperature and melting point. Fat is solid state in room temperatureOils is liquid state in room temperature

5. Fat is ester of fatty acid with saturated hydrocarbon chain while oil is the unsaturated hydrocarbon chain whether it is mono-unsaturated or poly-unsaturated

2.1: DIFFERENCE IN STRUCTURE

BETWEEN SATURATED AND UNSATURATED

FAT

SATURATED FAT• Saturated fatty acid contains an even number of carbon atom in an

unbranched chain.• The hydrocarbon chain that has no double bond present between carbon

atoms, thus consist of maximum number of hydrogen bonded to carbon atom in R group.

• Saturated fat like coconut fat, butter, ghee and fat of animal have higher melting point because of the presence of single covalent bond.

• Always solid at room temperature.• It arranged in tetrahedral arrangement of carbon atoms which this make

pack fairly closely together with parallel chain. • Weak van der Waals’ force is involved but the large surface area in the long

R group produce force strong enough to make the saturated fat become solid in room temperature.

•

UNSATURATED FAT• It has one or more double bond that formed by removed of

hydrogen atoms.• Unsaturated fat like vegetable oils, sunflower oil have low melting

point due to the presence of double covalent bond.• Unsaturated fat is found in liquid at room temperature.• Oils that contain one C=C double bonds per fatty acid chain are

called as “mono-unsaturated oils”.• Oils contain more than one C=C double bonds per fatty acid chain

are called as “poly-unsaturated oils”.• The presence of double bond make the melting point of fatty acid

is decrease due to prevention of close packing possible in saturated fatty acids.

• Unsaturated fat contain cis- isomer and trans- isomer.

• Cis- isomer is carbon in the carbon chain joined to the same side of C-C double bond

• trans- isomer is the carbon in carbon chain joined to the opposite site side of C-C double bond

F 2.2 Predict the degree of crystallization

(solidification) and melting point of fats and oils from

their structure, and explain the relevance of this

property in the home and in industry.

• The longer the carbon chain, the greater the molar mass, the stronger the van der Waal’s forces and the higher the melting points.

• The presence of double means the hydrocarbon chain is less straight, so weakening the Van der Waals forces by reducing the close contact between the chains.

• As a result, the greater the degree of unsaturation, the lower the melting point.

• The effect of double bonds on the ‘straightness’ of the hydrocarbon chain is much greater in cis-(H atom on the same side of carbon chain) than if here are in trans- (H atom on the opposite side of carbon chain) .

F 2.3 Deduce the stability of fats and

oils from their structure.

1. Saturated fats are more chemically stable than unsaturated fats.

2. This is because the unsaturated hydrocarbon is more reactive than saturated one.

3. Unsaturated fats are more chemically reactive and undergo a number of different chemical reaction due to the presences of one or more C-C double bond

4. The bond of carbon-carbon double bond is the reactive part of double bond and it is also involved in electrophonic addition reaction or free radical reaction.

FACTORS THAT AFFECTS THE MELTING POINTS AND HARDNESS OF SOLID

1. Mean Length Of Hydrocarbon• The larger the carbon chain, greater the molecular mass,

so stronger the Van Der Waals Force. Thus, higher the melting point.

2. Degree of unsaturation • Presence of double bond means that hydrocarbon chain is

less “straight”.• So, this will weaken the Van Der Waals Force by reducing

the close contact between chains. • Thus, as a result degree of unsaturation increase and the

melting point become lower.

3. Type of hydrocarbon that is present whether in cis- or trans around the double bond

• The effect of double bond on straighteness of hydrocarbon chain is much greater in cis- isomer compare than in trans isomer.

• Cis unsaturated oil have low melting point rather than trans unsaturated oils.

• Poly-unsaturated oil has low melting points and form of solid than mono-unsaturated oil.

– Example of Poly-unsaturated:• Sunflower oil• Corn oil• Fish oil

– Example of mono-unsaturated:• Olive oil• Peanut oil

F 2.4: DESCRIBE THE PROCESS OF

HYDROGENATION OF UNSATURATED FATS

Hydrogenation is the process of adding hydrogen atoms to carbon atoms

Hydrogenation occurs when:•Hydrogen gas is pumped into oil at very high pressure at 200°C•Requires three components: heat, a metal catalyst and the pressurized hydrogen gas•Nickel is introduced to the hydrogen gas as the gas is forced into the oil. •The gas and metal are heated, and the heat helps them bond•The metal atoms also bond to the carbon atoms, allowing the hydrogen atoms to insert themselves between the carbon atoms that make up unsaturated fat molecules. •The bonds between the carbon atoms become saturated with hydrogen atoms, turning what was once an unsaturated fat into a saturated fat.

F 2.5: DISCUSS THE ADVANTAGES AND DISADVANTAGES OF HYDROGENATING FATS AND OILS

ADVANTAGES

The product is semi-solid or solid, rather than a liquid which is more convenient for some cooking techniques

The product is more stable because the rate of oxidation is decreased

The texture (hardness and plasticity) of the product can be controlled

Increases the shelf life of prepared foods

DISADVANTAGES

Raises the levels of low-density lipoprotein, or LDL, cholesterol in your blood

Can also lower the levels of high-density lipoproteins, or HDL. HDL is the "good" cholesterol that helps prevent LDL from sticking to the walls of your arteries

Poses a heart disease risk