Simple Lipids

Question 1

Why are simple lipids called as neutral lipids

Answer 1

They are called neutral because they are uncharged due to absence of ionisable groups

Question 2

Why are simple lipids called as Triglycerides

Answer 2

They are esters of glycerol with various fatty acids. Since the 3 hydroxyl groups of glycerol are esterified , the neutral fats are called as Triglycerides

Question 3

What are all the types triglycerides ( Fats and oils)

Answer 3

1)Simple Triglycerides
2) Mixed triglycerides

Question 4

What are simple Triglycerides

Answer 4

If the three fatty acids connected to glycerol are of the same type it is called as simple Triglycerides
e.g, Tripalmitin

Question 5

What are mixed Triglycerides

Answer 5

If the three fatty acids connected to glycerol are of different types it is called mixed Triglycerides
e.g, stearo- diolein and palmiti-oleo-steaein

Question 6

What is the difference between fats and oils

Answer 6

Oils are liquid in room temperature whereas fats are solids in room temperature

Question 7

What are all the physical properties of fats and oils

Answer 7

1) Freshly prepared fats and oils are colorless, odourless and tasteless. Any colour or taste is due to association with foreign substance
2) Fats have specific gravity less than 1 and therefore, they float on water
3) Fats are insoluble in water but soluble in organic solvents
4) Melting points of fats are usually low

Question 8

What are all the chemical properties of fats and oils

Answer 8

1) Hydrolysis
2) Saponification
3) Halogenation
4) Hydrogenation or hardening of oils
5) Oxidation (Rancidity)

Question 9

What is hydrolysis of fats and oils

Answer 9

They are hydrolyzed ( Broken down in the presence of water) into fatty acids and glycerol by the action of steam, acid, alkali or enzymes ( lipase of pancreas) . Glycerol and fatty acids are produced at the end

Question 10

What is Saponification of fats and oils

Answer 10

Alkaline hydrolysis produces glycerol and salts of fatty acids ( Soaps )

Question 11

What is Halogenation of fats and oils

Answer 11

Neutral fats containing unsaturated fatty acids have the ability of adding halogens at the double bond

Question 12

What is hydrogenation or hardening of oils

Answer 12

It is a type of addition reaction in which hydrogen is added into the double bond of unsaturated fatty acids
It is done unde high pressure of hydrogen and is catalysed by finely divided nickel

Question 13

What is oxidation ( Rancidity )

Answer 13

It is a toxic reaction of Triglycerides which leads to unpleasant odour or taste of oils and fats developing after oxidation by oxygen of air

Question 14

What is Rancidity

Answer 14

It is a physio-chemical change of fats that leads to development of bad odour or taste or abnormal colour after ageing in the exposure to oxygen and moisture

Question 15

What are the types of Rancidity

Answer 15

1) Hydrolytic Rancidity
2) Oxidative Rancidity
3) Ketonic Rancidity

Question 16

What is Hydrolytic Rancidity

Answer 16

It results from the slight hydrolysis of the fat by lipase from bacterial contamination leading to the liberation of free fatty acid and glycerol at hig temperatures and moisture

Question 17

What is oxidative Rancidity

Answer 17

It is oxidation of fat or oil by exposure to air, oxygen, light or heat producing peroxide derivatives which on decomposition gives substance like peroxide, aldehyde and ketone which have bad odour and toxic

Question 18

What is Ketonic Rancidity

Answer 18

It is due to contamination with certain fungi such as aspergillus Niger on fats such as coconut oil. Ketones, fatty aldehydes and fatty alcohols are formed

Question 19

What accelerates Ketonic Rancidity

Answer 19

Moisture accelerates Ketonic Rancidity

Question 20

What is iodine number or value

Answer 20

It is the number of grams of iodine absorbed by 100 grams of fat or oils

Question 21

What is the use of iodine number

Answer 21

It is the measure for the degree of unsaturation if the fat as a natural property for it

Question 22

What is Saponification number

Answer 22

It is the number of milligrams of KOH required to completely saponify one gram of fat

Question 23

What is the use of Saponification number

Answer 23

Since each carboxyl group of a fatty acid reacts with one mole of KOH during Saponification, therefore the amount of alkali needed to saponify certain weight of fat depends upon the number of fatty acids present per weight. Thus fats with short chain acids will have higher Saponification number than long chain fatty acids

Question 24

What is acids number

Answer 24

It is the number of milligrams of KOH required to neutralize the free fatty acids present in one gram of fat

Question 25

What is the use of acid number

Answer 25

It is used for detection of Hydrolytic Rancidity as it measures the amount of fatty acids present

Question 26

What is Reichert- Meissl number

Answer 26

It is the number if millilitres of 0.1N KOH required to neutralize the water soluble fatty acids distilled from 5 grams of fat

Question 27

What is the use of Reichert-Meissl number

Answer 27

This studies the natural composition of the day and is used for detection of fat adulteration

Question 28

What is acetyl number

Answer 28

It is number of milligrams of KOH required to neutralize the acetic acid liberated from hydrolysis of 1 gram of acetylated fat

Question 29

What is the use of acetyl number

Answer 29

It is used for studying the natural property of the fat and to detect adulteration and Rancidity