Simple Lipids Flashcards
Why are simple lipids called as neutral lipids
They are called neutral because they are uncharged due to absence of ionisable groups
Why are simple lipids called as Triglycerides
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
What are all the types triglycerides ( Fats and oils)
1)Simple Triglycerides
2) Mixed triglycerides
What are simple Triglycerides
If the three fatty acids connected to glycerol are of the same type it is called as simple Triglycerides
e.g, Tripalmitin
What are mixed Triglycerides
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
What is the difference between fats and oils
Oils are liquid in room temperature whereas fats are solids in room temperature
What are all the physical properties of fats and oils
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
What are all the chemical properties of fats and oils
1) Hydrolysis
2) Saponification
3) Halogenation
4) Hydrogenation or hardening of oils
5) Oxidation (Rancidity)
What is hydrolysis of fats and oils
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
What is Saponification of fats and oils
Alkaline hydrolysis produces glycerol and salts of fatty acids ( Soaps )
What is Halogenation of fats and oils
Neutral fats containing unsaturated fatty acids have the ability of adding halogens at the double bond
What is hydrogenation or hardening of oils
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
What is oxidation ( Rancidity )
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
What is Rancidity
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
What are the types of Rancidity
1) Hydrolytic Rancidity
2) Oxidative Rancidity
3) Ketonic Rancidity
What is Hydrolytic Rancidity
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
What is oxidative Rancidity
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
What is Ketonic Rancidity
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
What accelerates Ketonic Rancidity
Moisture accelerates Ketonic Rancidity
What is iodine number or value
It is the number of grams of iodine absorbed by 100 grams of fat or oils
What is the use of iodine number
It is the measure for the degree of unsaturation if the fat as a natural property for it
What is Saponification number
It is the number of milligrams of KOH required to completely saponify one gram of fat
What is the use of Saponification number
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
What is acids number
It is the number of milligrams of KOH required to neutralize the free fatty acids present in one gram of fat
