Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st year (First Year) Biochemistry ppt lectures Topic 3 L4 Simple Lipids Notes. - biochemistry notes pdf, biochemistry mbbs 1st year notes pdf, biochemistry mbbs notes pdf, biochemistry lecture notes, paramedical biochemistry notes, medical biochemistry pdf, biochemistry lecture notes 2022 ppt, biochemistry pdf.
Study Of
Simple Lipids/Neutral Lipids
Triacylglycerols/Triglycerides
? Chemical name of Fat/Oil is Triacylglycerol
(TAG).
? TAG is a Simple, Glycerol based
,Neutral Lipid.
Chemical Structures Of
Triacylglycerol (TAG)
Triacylglycerol/Fats/Oils
? TAG/Fats/Oils are
? Chemically Esters of
? Three Fatty acids ( Same or Different)
? with one Glycerol (Trihydric Alcohol).
Most Common Fatty Acids in Triacylglycerol
Fatty acid
Carbon:Double bonds
Double bonds
Myristic
14:0
Palmitic
16:0
Palmitoleic
16:1
Cis-9
Stearic
18:0
Oleic
18:1
Cis-9
Linoleic
18:2
Cis-9,12
Linolenic
18:3
Cis-9,12,15
Arachidonic
20:4
Cis-5,8,11,14
Eicosapentaenoic
20:5
Cis-5,8,11,14,17
Docosahexaenoic
22:6
Cis-4,7,10,13,16,19
CH3(CH2)n COOH
?TAG is Neutral or Non
polar lipid.
?Since TAG structure has
no charged/polar groups
in its structure.
Types Of Triacylglycerol
Based On Nature Of Fatty Acid
?Simple TAG
?Mixed TAG
? Simple TAG: Three same Fatty
acids are esterified to Glycerol to
form simple TAG.
? Examples of Simple TAG:
?TriPalmitin
?TriStearin
?TriOlein
? Mixed TAG:
? The 3 different Fatty acids
esterified to Glycerol to form a
mixed TAG.
? Mixed TAG's are more
predominant in nature.
? In a Mixed TAG
? First Carbon C1 -has Saturated Fatty acid
? Second position C2-has Unsaturated
Fatty acid-PUFA
? The 3 rd position C3 Fatty acid in TAG has
- either Saturated/Unsaturated fatty
acid
Olive Oil Rich In Simple TAG
? Olive oil contains mostly TAG as Triolein, which has
three Oleic acids.
Sources OF Triacylglycerol
To
Human Body
?Exogenesis source of TAG :
?Dietary Fats/Oils
?Endogenous source of TAG :
?Liver Lipogenesis in wel fed
condition
?Using Glucose product Acetyl-
CoA.
Dietary Sources Of TAG
?Animal Fat (Solid)
?Plant Oils (Liquid)
Fats (solid Triacylglycerol)
Oil (a liquid Triacylglycerol)
Occurrence/Distribution Of TAG
qTAG is a most widely
distributed abundant
natural lipid.
TAG Major Lipid Form Of Human Body
?Predominant Lipid ingested
in Human diet is TAG 98%.
?Abundant Lipid of human
body Lipid is TAG 95 %.
Transportation Of TAG in
blood is By Lipoproteins
?Chylomicrons :
?Transports
exogenous dietary
TAG
?VLDL:
? Transports
endogenous TAG
Biomedical Importance Of TAG
S.No Distribution/Location Of TAG in Role of TAG
Human Body
1
Predominant Dietary Form of
Dietary and Calorific
Lipid Ingested in GIT
Value- Secondary
Source of Energy
2
Adiposecytes/Depot Fat-
Reservoir of Energy
Exclusively TAG
3
Subcutaneous layer /Below Skin Insuating Effect,
Regulates Body
Temperature
4
Fat Pad around Internal Soft
Mechanical Shock
Visceral Organs
absorbers
1.TAG Serves As Source Of Energy
? TAG has high calorific value
(9Kcal/gram) more than
Carbohydrates (4 Kcal/gram ).
2.TAG Reservoir Of Energy
Storage form of Lipid in
human body is TAG.
Triacylglycerols In Its Structure
Links and Stores Fatty acids
? Fatty acids are not stored in free
form in living beings.
? Fatty acids are stored in bound
form as TAG.
? Thus TAG is a storage form of
Fatty acids .
Criteria's For TAG To Be Chosen As
Reservoir of Energy
? TAG is highly reduced and
anhydrous form.
? Hence chosen as energy
reserve of the body.
? Because of insolubility of TAG in
aqueous phase:
? Body TAG are mostly found in
isolated compartments as
droplets.
? TAG in anhydrous form is packed
in Adipocytes
(Depot Fat)
3.Store House Of TAG
is High
In Comparison To
Glycogen Stores
? More content of energy can be
stored by TAG in comparison to
Glycogen stores.
? 1 gm of anhydrous TAG
stores more than 6 times as
much as energy as 1 gm of
hydrated Glycogen.
? Hydrated molecules requires more space.
? TAG stored in anhydrous form
requires less space.
? In contrast Glycogen being hydrated
requires more space.
(1 gm of Glycogen binds with 2gm of water)
? TAG When excess serves as
an energy reservoir stored in
Adipocytes as :
?Anhydrous form
?Concentrated
?Unlimited amount
?Stores of TAG are utilized in
between meals and
starvation phase.
?A good storage of depot
Fat can suffice for 2-3
months in starvation
condition.
? The stored TAG is used as long term
energy source for body activities.
? In long marathon race energy for
muscle activity is provided by the
hydrolysis of depot TAG.
4. TAG Regulates Body Temperature
? The subcutaneous Fat layer is a TAG
? TAG is a bad conductor of heat and
electricity and serves as a thermal
and electrical insulator.
? Which prevents loss of heat from the
body and plays important role in
regulating body temperature.
5.TAG Protects Internal Visceral
Organ and Systems
? A presence of Fatty (TAG) pad
around the soft delicate
internal visceral organs
? Protects from mechanical
trauma or injury by acting as
a shock absorber.
?TAG provides shape to
body and
?Keep skin smooth and
supple.
Remember TAG is
not associated to
biomembranes.
? MAG and DAG are derived
Lipids.
? Monoacylglycerol and
Diacylglycerol are hydrolytic
products of Triacylglycerol.
? These are produced during TAG
metabolism in the body.
?Monoacylglycerol (MAG)
/(Monoglycerides): A Glycerol esterified
with one fatty acid.
?Diacylglycerol (DAG) (Diglycerides):
?A Glycerol esterified with two fatty acids.
Healthy TAG In Human Body
? Ingesting Natural Mixed Form ? PUFAs and Short chain
FAs
? Avoiding Trans Fats
? Balanced/Moderate ingestion
? No excess or deficient TAG stores
? Normal serum TAG levels < 150 mg%
Disorders Associated To TAG
Bad About : TAG/ Fats and Oils
?Excess Fat leads to Obesity
?Increases risk for Diabetes Mel itus
?Leads to Coronary Artery disease
?MI, Stroke
? Susceptible to Cancer
50
Disorders Related To TAG
? Normal Fat content of adult:
?Men 21%
?Women 26%
? If the Fat content of an adult
body goes above the normal
content the condition is termed
as Obesity.
? Obesity has excess fat
depots.
? Truncal/central obesity is a
risk factor for heart attack.
? Obesity has abnormal Lipid
metabolism.
? Increased Blood Cholesterol and
Lipoproteins.
vObese persons has high risk of
vDiabetes mel itus
vAtherosclerosis and CVD
? Consequently lead to
Metabolic Syndrome
Prevent Obesity
Properties Of Triacylglycerol
Lipid Peroxidation
(autoxidation)
Lipid Peroxidation
Is a source of Higher Free Radicals
? During Oxygen metabolism in body.
? Oxygen derived free radicals (RO.,OH.,ROO.)
with unpaired electrons are released.
? These Reactive Oxygen Species (ROS) , Free
radicals interact and oxidize double bonds of
PUFAs leads to chain reactions of lipid
peroxidation.
? Steps of Lipid peroxidation
reaction:
?Initiation
?Propagation
?Termination
? PUFAs are more prone for
peroxidation.
? Lipid peroxidation Provide
continuous Free radicals.
? Thus has potential y
devastating effects in the
body.
? In vitro peroxidation of Lipids
deteriorates the quality of
Fats and Oils
? Makes the Fat/Oil rancid and in edible.
? Fat/oil has bad taste and odor
? Decreases the shelf life of Fats and Oils.
? In vivo peroxidation of
membrane Lipids damages cel s & tissues
? Lipid peroxidation has devastating
effects on body Lipids.
? Increases risk of Inflammatory diseases
? Ageing
? Cancer
? Antioxidants control and reduces
In vivo and In vitro Lipid peroxidation.
? Natural y occurring antioxidants are :
?Vitamin E
?Vitamin C
?Beta Carotene
? Body Enzymes as Antioxidants:
?Catalase
?Glutathione Peroxidase
?Superoxide Dismutase
? Other Substances as Antioxidants:
?Urate
?Bilirubin
? Food Additives as Antioxidants:
?Alpha Naphtol
?Gallic Acid
?Butylated Hydroxy Anisole (BHA)
?Butylated Hydroxy Toluene (BHT)
? Preventive Antioxidants:
? Reduces rate of Chain initiation of
Lipid peroxidation
?Catalase
?Peroxidase
?EDTA
?DTPA
? Chain Breaking Antioxidants:
? Interferes the chain propagation
of Lipid peroxidation.
?Vitamin E
?Urate
Rancidity Of Fats/Oils
Rancidity
? Rancidity is a physico chemical
phenomenon
? Which deteriorates Fats and Oils
? Resulting in an unpleasant taste
,odor and color of Fat/Oil
(Rancid Fat/oil)
?Rancid Fat is inedible
Factors Causing Rancidity
? Double bond containing /Unsaturated
Fatty acids are unstable and ready for
peroxidation and rancidity.
? Single bond containing/Saturated Fatty
acids are stable and less peroxidized
and made rancid.
PUFAs are more prone to
Rancidity
Since Double bonds are
more susceptible to Lipid
peroxidation
Causes Of Rancidity
? Fats and Oils get Rancid on Ageing.
? Various Factors aggravates rancidity of Oils
and Fats:
? Improper handling by an exposure to:
?Light
?Air (Oxygen)
?Moisture
?Microbes
Types and Mechanism
Of Rancidity
Types Of Rancidity
?Oxidative Rancidity
?Hydrolytic Rancidity
?Ketonic Rancidity
? Oxidative Rancidity:
? PUFAs having double bonds are
easily oxidized to form its
peroxides.
? By the action of Oxygen Derived
Free radicals (ODFR).
? The cel ular Lipids are also
likely to get peroxidized by
Free radical action causing
damage to biomembranes.
? Hydrolytic Rancidity:
? Long Chain Saturated fatty acids are
hydrolyzed by Bacterial Enzymes .
? To produce Dicarboxylic acids,
Aldehydes, Ketones etc which make
a Fat rancid.
Ketonic Rancidity
? It is due to the contamination with
certain Fungi such as Asperigil us Niger
on Oils such as Coconut oil.
? Ketones, Fatty aldehydes, short chain
fatty acids and fatty alcohols are formed.
? Moisture accelerates Ketonic rancidity.
? Rancidity gives bad odor and
taste to rancid Fats/oils.
? Due to Dicarboxylic acids
,Ketones , Aldehydes Produced
during the process of
Prevention of Rancidity of Fat/Oil By :
q Good storage conditions
q Less Exposure to light
q Low Oxygen, moisture
q No very High temperatures
q No Bacteria or fungalcontamination
q Addition of Antioxidants
Prevention Of Rancidity
? Rancidity can be prevented by
proper handling of oils
?By keeping fats or oils in wel
closed containers in cold,
dark and dry place.
Prevention Of Rancidity
?Avoid exposure to direct sunlight,
moisture and air.
?Avoid over and repeated heating of
oils and fats.
? Removal of catalysts such as Lead
and Copper from Fat/Oils that
catalyzes rancidity prevents
rancidity.
Antioxidants Prevent Rancidity
?Antioxidants are chemical
agents which prevent
peroxidation and
Hydrolysis of Fats/Oils.
? Examples Of Antioxidants:
? Tocopherol(Vitamin E)
? Vitamin C
? Propyl Gallate
? Alpha Napthol
? Phenols
? Tannins
? Hydroquinone's.
? Butylated Hydroxy Anisole(BHA)
? Butylated Hydroxy Toluene (BHT)
? The most common natural
antioxidant is vitamin E
that is important in vitro
and in vivo.
? Vegetable oils are associated with
high content of natural antioxidants
(Vitamin E),
? Hence oils do not undergo rancid
rapidly
? As compared to animal fats which
are poor in natural y associated
antioxidants .
? Rancidity of Fats and Oils is
prevented by adding Antioxidants.
? Thus addition of Antioxidants
increases shelf life of
commercial y synthesized Fats
and Oils.
Hazards of Rancid Fats:
1. Rancidity destroys the content of
polyunsaturated essential fatty acids.
2. Rancidity causes economical loss because
rancid fat is inedible.
3. The products of rancidity are toxic, i.e.,
causes food poisoning and cancer.
4. Rancidity destroys the fat-soluble vitamins
(vitamins A, D, K and E associated with it.
Others Properties Of TAG
Depends On Nature Of Fatty Acids
Chain Length Of Fatty acids
Of TAG affects Melting Point
? "Hardness" of the Fat/TAG depends on chain
length.
? < 10 carbons in Fatty Acid = liquid
? >20 carbons in Fatty Acid = solid
Acetic Acid (2 C)
Vinegar
Liquid
Stearic Acid (18 C)
Beef Tallow
Solid
Arachidic Acid (20 C) Butter
Solid
Differences In Fat and Oil
? Fat and Oils are different in Physical
Characteristics
? Fat is solid at room temperature.
? Oil is liquid at room temperature.
? TAG of Fat is solid since chemically
composed of long and saturated
fatty acids.
? Source of Fat is Animal foods.
? TAG of Oil is liquid as composed of
short and unsaturated fatty acids.
? Source of Oil is plant.
Hydrogenation Of Fat/Oil
? Treatment of Oils(TAG) rich in PUFAs with
Hydrogen gas, (H2).
? Catalyst required (Nickel).
? Adding Hydrogen at double bonds of PUFAs.
? It is also cal ed "Hardening of Oils"
? Hydrogenation converts PUFAs with cis form
to trans form.
? Margarine
? Vanaspati Dalda Crisco, Spry, etc.
Advantages and Disadvantages Of
Hydrogenation Of Fat /Fatty acids
Advantages Of Fat Hydrogenation
? Hydrogenation transforms unstable
,unsaturated , liquid TAGs:
?To stable, saturated, solid TAGs
?Reduces risk of Rancidity
?Increases shelf life and business.
?Example : Vanaspati Dalda ,Margarine.
Disadvantages Of Hydrogenation Of
Fat/Fatty acids
Trans Fats increases the risk of
Atherosclerosis and CVD.
? Hydrogenated trans Fats are
more stable.
? Body has no enzyme system to
oxidize and metabolize trans
fatty acids.
?Remember
Hydrogenated Fats
are Bad for Health.
? Summary Of Fat Hydrogenation:
? Hydrogen atoms are added to unsaturated
Fatty acids
?Make liquid oils more solid and more
saturated.
?Create trans fatty acids.
?Reduces peroxidation of Fatty acids.
?Resists rancidity
?Reduces metabolism
?Increases retention
?Increase risk of cardiovascular disease.
?Note
?Try eat more natural TAGs.
?Avoid Processed Fats.
Tests To Check Purity
Of
Fat and Oil
? Several laboratory tests are
employed to:
?Check the purity
?Degree of adulteration
?Biological value of Fat and
Oils.
Tests to Check Purity of Oils and Fats
Tests To Check Purity of Oils Importance/Significance
Iodine Number
Index of unsaturation and
content of unsaturated fatty
acids
Saponification Number
To know Chain Lengths of
Fatty acids
Acid Number
Checks purity of Refined oils
Reichert Meissl (RM)
Useful in testing the purity of
Number
butter
Iodine Number
? Iodine number is
Grams/Number of Iodine
absorbed by 100 gram of Fat
/Oil .
? Iodine Number is calculated by
method of Iodometry.
Use Of Iodine Number
? Iodine number is useful to
know
? The index of unsaturation and
content of unsaturated fatty
acids present in the Fat/Oil.
? Iodine number is directly
proportional to unsaturated
bonds of PUFAs in a Fat/Oil.
? High value of Iodine number of
oil indicates more content of
Unsaturated Fatty acids in it.
Name Of Oils
Iodine Number
Coconut Oil
7-10 (Least)
Butter
25-28
Ground Nut Oil
85-100
Sunflower Oil
125-145
Soya bean Oil
135-150
Linseed Oil /Flax seed 175-200 (Highest)
Oil
? Determination of Iodine number helps
in knowing the degree of
adulteration of tested oil sample.
? If Linseed oil is adulterated with an oil
whose content is high in saturated
fatty acids will give lower Iodine
number than the reference values.
Saponification Number
? Saponification number is
mil igram/number of KOH molecules
required to hydrolyze and saponify one
gram of Fat/Oil.
? Saponification number gives the
idea of molecular size/chain
length of Fatty acids present in 1
gram of Fat.
? 1 gram of Fat/oil with long chain
fatty acids has lower
saponification number.
? 1 gram of oil containing short chain
fatty acids has high Saponification
number.
? 1 gram Oil with short chain fatty
acids has higher saponification
number.
? Since it has more COOH groups for
KOH reaction.
? 1 gram Fat/Oil with long chain
fatty acids has low
saponification number.
? Since in 1 gram of Fat has few -
COOH groups of fatty acids to
react with KOH.
Oils
Saponification Number
Coconut Oil
250-260
Butter
230-250
Jojoba Oil
69- 80
Olive Oil
135-142
Acid Number
? Acid number is mil igram of KOH
required for complete
neutralization of free fatty acids
present in one gram of Fat/Oil.
? Acid number checks the purity of
Refined oils.
? Refined oils are free from free fatty
acids and has zero Acid number.
? Increased Acid number of refined
oil suggests bacterial/chemical
contamination and unsafe for
human consumption.
Reichert Meissl (RM)Number
? RM number is 0.1 N KOH
required for complete
neutralization of soluble
volatile fatty acids distil ed
from 5 gram of Fat .
?R.M Number of Butter is
25-30.
?The R.M number of
other edible oils is less
than 1.
? R.M number is useful in testing
the purity of butter
? Since it contains good
concentration of free volatile
fatty acids viz: Butyric, Caproic
and Caprylic acid.
?Adulteration of butter
reduces its R.M
number.
Differentiation Between
Fats And Oils
Fats
Oils
Fats are TAGs composed of Long
Oils are TAGs composed of short
and Saturated Fatty acid.
and Unsaturated Fatty acids.
Fats solid at room temperature
Oils liquid at room temperature
Fat has high melting point
Oils have low melting point
Fats -animal In Origin
Oils -Plant in Origin
Example: Lard (pork Fat)
Example: Safflower Oil
Fats has low antioxidant content
Oils have high antioxidant content
and get easily Rancid
and do not get easily Rancid
Fats are more stable
Oils are less stable
Fats are less metabolizable in body. Oils are readily metabolizable in the
body.
High content of dietary Fats has
Oils have low risk for
high risk for Atherosclerosis.
Atherosclerosis.
This post was last modified on 05 April 2022