This document discusses lipids (fats), including their classification, structure, properties, digestion, absorption, transport, and functions in the body. It covers simple lipids like oils and fats, compound lipids, waxes, and derived lipids. Key points include that fats are important for energy storage, absorbing fat-soluble vitamins, and providing essential fatty acids. High cholesterol and saturated fat intake can increase risk of cardiovascular disease.

1. Fat (Lipids)

2. Classification
Simple Lipids (Oils and Fats)
Compound Lipids (Phospholipids and
Glycolipids)
Waxes
Derived Lipids

3. Simple Lipids
Oils and Fats :
• Esters of fatty acids and glycerol
• Oils – liquids at 200C
• Fats – solids at 200C

4. Compound lipids
 Phospoliplids
 Contain phosphoric acid and nitrogenous base
in addition to glycerol and FA
 Lecithin, Cephalins, Plasmalogens
 Glycolipids
 Complexs lipids – CHO in comination with
fatty acids and sphingosine
 Cangliosides, Cytolipin etc.,

5. Waxes and Derived Lipids
Waxes
Ester of FA and long chain aliphatic
alcohols
Derived lipids
Fatty acids, alcohols and sterols

6. Saturated and Unsaturated FA
Saturated FA
• Lauric acid, Myristic, Palmitic, Stearic,
etc.
Unsaturated FA
• Linoleic, Linolenic, Oleic, Arachidonic,
etc.
• Short chain fatty acids
• Medium Chain fatty acids (MCT)
• Long chain Fatty acids

7. Properties of Fats
 Solubility:
 Soluble in ethyl ether, petroleum ether,
acetone, alcohol and benzene
 Quantity in food material – estimated by
extraction with ethyl ether or petroleum ether
 Saponification value (number)
 No. of mg of KOH required to saponify 1 g of
fat or oil

8.  Iodine value (Number)
 measure of extent of UFA present in fats and
oils
 No. of grams of iodine absorbed by 100 g of
fat
 Reichert-Meissl Value
 Number of mg of 0.1N alkali (NaOH or KOH)
required to neutralise the steam volatile water
soluble fatty acids preseint in 5 g of fat.
 Determines – amt of butyric acid and caproic
acid which readily soluble in water

9. Refined and Hydrogenated Fats
Refining
Refining by alkali -to remove FFA,
Bleaching with fullers earth or activated
carbons -remove colour
Deodouriing with super heated steam.

10. Hydrogenation
 Addition of hydrogen bond –USFA- under
optimal temperature and pressure -
presence of nickel as catalysts.
 Hydrogen added to the unsaturated
linkages.
 Liquid fat – solid fat and UFA contents
decreased
 Vanaspathi – refined groundnut oil
 Before hydrogenation – cottonseed oil and
soybean oil added.

11. Rancidity of Fats
 development of off-flavours in fats
 Types : Hydrolytic, Oxidative and ketonic
 Hydrolytic rancidity
 When fat is hydrolysed by lipase - free fatty acid are
formed.
 Oxidative rancidity
 Oxidation takes place at the unsaturated linkage
(double bond).
 Addition of oxygen to the unsaturated linkage results in
the formations of peroxide which yields aldehydes and
ketones having pronounced off odour.

12. Ketonic rancidity
Action of fungi (Aspergillus niger, blue
green mould, penicillium glaucum) on
coconut or other oilseeds.
Tallowy odour developed – due to
aldehydes and ketones formed by
action of enzymes prsent in fungi.
Anti oxidants – prevent oxidation –
Butylated Hydroxy Anisole (BHA); BHT
(toluene)

13. Functions of Fats
 Concentrated source of energy
 Essential for absorption of vitamins A,D,E,K and
especially carotenoids (Pro vit A) present in food
of vegetable origin.
 Animal fats eg:- fish liver oil, butter and ghee
contain vitamin A and many vegetable fats
contain vitamin E and red palm oil is a good
source of carotene (pro vit A)
 Contains essential fatty acids like linolic, linolenic
and arachidonic acids which are essential for
maintaining tissues in normal health.

14.  Help to reduce the bulk of diet as starchy foods
absorb lot of water during cooking.
 Improve the palatability of the diet and gives
satiety value a feeling of fullness in the stomach
 Essential for the utilisation of galactose, present
in lactose.
 Phospholipids and other compound lipids are
essential constituents of nervous tissue.
 Fats are deposited in the adipose tissue and this
deposit serves as the source of energy during
starvation. Further adipose tissue functions like
an insulating material against cold and physical
injury.

15. Digstion and Absorption
 Fat is not digested in the stomach.
 Presence of fat - delays the emptying of the
stomach.
 Stomach – fats hydrolysed by pancreatic and
intestinal lipase into a mixture of diglycerides,
monoglycerides and fatty acids.
 Bile - essential for the digestion and absorption -
helps to emulsify fats before digestion.
 Products of digestion pass into the cells of the
intestinal wall, where synthesis of new glycerides
takes place.

16. Lipids pass through - small intestine to
thoracic duct and then to the blood
stream in the form of fine particles
known as chylomicrons.

17. Lipids in Blood
 Normal human plasma -post absorption
state contains -500 mg of total lipids
(per100ml)
 120 mg are triglycerides,
 160 mg phospholipids,
 180 mg cholesterol
 10-15 mg free fatty acids.
 Plasma contains two lipoprotein
 Involved in the transport of fat.

18. Hypercholesterolemia and
Coronary heart disease
Factors influence the serum cholesterol
level
• Calorie in take
• Cholesterol intake
• Fat intake

19. Risk of CVD
 Calorie excess -increase serum cholesterol level
 Dietary intake of cholesterol -vary from 500-1200
mg.
 Human body synthesis daily about 2000 mg
cholesterol.
 Saturated fats tends to increase markedly the
serum cholesterol level
 Blood cholesterol level exceeds 200 mg / 100 ml
-incidence of atherosclerosis and coronary heat
disease is high.

20. Sources of Fat
Rice sources
Fats and oils
Nuts
Meat
Fair sources
Fresh fruits & vegetables
Roots & tubers

21. Requirements
Age groups RDA (g/d)
Adults (male) 20
Adults (Female) 20
Pregnant woman 30
Lactating mother (0-6 months) 45
Children (1-9 years) 25
Boys & Girls (10-18 years) 22
ICMR, 2010