This document discusses lipids (fats) including their composition, classification, functions, sources, and deficiencies. Lipids are comprised of carbon, hydrogen, and oxygen and provide 9 calories per gram. They are classified as simple lipids, compound lipids, waxes, and derived lipids. The main lipids in diet are triglycerides, phospholipids, and sterols. Triglycerides make up 95% of dietary and body lipids and are broken down into glycerol and fatty acids. Phospholipids are important structures in membranes. Sterols are precursors to bile acids and sex hormones. Fats have many important functions like being an energy source and aiding vitamin absorption. Deficiencies can cause skin disorders like

1. Principles of food science and nutrition
Assignment : lipids(fats)

2. Lipids (fats)

3. Fats – composition and chemistry, classification,
functions
Nutritional disorders – fats deficiency
Energy metabolism – digestion,absorption and
utilization

4. Introduction
Lipids are a group of naturally occurring substances.
They occur widely in plant and animal Kingdom.
The basic structure of lipids is comprised of
carbon,hydrogen and oxygen.
Each gram of fat provides 9.0kcal of energy.

5. Classification:
1. Simple lipids
2. Compound lipids
3. Waxes
4. Derived lipids

6. Lipids present in diet:
1. Triglycerides:
It comprises about 95 percent of food lipids and
body lipids.
All triglycerides are similar in structure.
When triglycerides are metabolized the glycerol is
converted into glucose.
2. Phospolipids:
They are the important structure of all membranes.
They are similar to triglycerides, but contain two
polyunsaturated fatty acid.

7. 3. Sterols:
It is the precursor of bile acids and sex hormones.
It is manufactured in all tissues of body, except brain.
Cholesterol, like lecithin is also present in foods, egg
yolk,meat.
A transport mechanism of cholesterol called low-
density lipoprotein is likely to cause risk for
cardiovascular disease called atherosclerosis.

8. Functions of fats:
It is a concentrated source of energy
Fat is essential for absorption of vitamin A,D,E,K and
carotenoids.
Vegetable fats are good sources of vitamin E.
Fats reduce the bulk of the diet as they provide much
calories.
Fats are deposited in adipose tissue.

9. Properties of fats:
Fats are soluble in organic solvents such as acetone,
petroleum ether etc.
Saponification value: it is defined as number of
milligrams of potassium hydroxide.
Iodine value: it is the measure of extent of
unsaturated fatty acids present in fats.

10. Sources:
Rich sources of EFA: safflower, sunflower, Niger seed
linseed and soybean oils are rich sources of EFA.
Good sources: rape seed,groundnut and rice bran oils.
Fair sources: egg yolk,fat,poultry fat etc.
Poor sources: coconut oil,palm,kernel oil, mutton etc.

11. Factors affecting the absorption of lipids:
Activity of pancreatic lipase.
Secretion of sufficient bile.
The lipid synthetic activity of intestinal mucosa.

12. Fatty acid deficiency in human beings:
1. Phrynoderma:
This is one of the common disorders of malnutrition
observed in adults and children
Deficiency in infants:
Hansen and co workers have reported that infants
fed on EFA deficient diet developed perennial
irritation in skin.

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