This document defines lipids and discusses their structure, classification, properties, and functions. Lipids are organic compounds that are insoluble in water but soluble in organic solvents. They typically have a glycerol backbone with two fatty acid tails and a phosphate group. Lipids can be classified based on their structure, ability to saponify, and polarity. They serve important roles as energy stores, structural components of cell membranes, and carriers of fat-soluble vitamins.

1. LIPIDS
FSQN-235
Food Biochemistry
ATHARV KURHADE
MITU20BTFT0020

2. Contents
● Definition
● Structure of Lipids
● Classification of Lipids
● Properties of Lipids
● Functions of Lipids

3. Definition of Lipids
“Lipids are organic compounds that contain hydrogen, carbon, and
oxygen atoms, which forms the framework for the structure and
function of living cells.”
OR
“Lipids are a heterogeneous group of organic compounds that are
insoluble in water and soluble in non-polar organic solvents.”

4. Structure of Lipids
 Lipids are an essential component of the cell membrane. The structure is
typically made of a glycerol backbone, 2 fatty acid tails (hydrophobic), and a
phosphate group (hydrophilic).
 The hydrophilic part faces outward and the hydrophobic part faces inward. This
arrangement helps monitor which molecules can enter and exit the cell.

5. Classification of Lipids
Lipids areclassifiedon several basis, i.e.
 Based on itscomplexity/structure
 Abilitytoreact withalkali (saponification process) to
formsoap
 Polarity(charge on itscomponents).

6. Based on Structure
Based on structure, lipids can be classified intothreegroups, i.e.simple, complex and
derived lipids.
 Simple lipids:
These lipids are esters of free fatty acids and alcohol components, and
include fats, oils and wax esters. They can be hydrolyzed to two different components,
usually an alcohol and an acid.
 Compound lipids:
These lipids include glycerophospholipids (phospholipids),
glyceroglycolipids (glycolipids), and sphingolipids. On hydrolysis, it yields three or
more different compounds.
 Derived lipids:
These are compounds obtained during the hydrolysis of simple and
compound lipids. It also includes sterols, vitamins, pigments, hydrocarbons, etc.

7. Based on Saponification
The abilityof lipids toreact withalkali (saponification process) to formsoap.
 Saponifiablelipids :
- React withalkaliandformsoap
- Present in large amount. e.g.Glycerides, phospholipids,fatty acids, cholesterol ester,etc.
 Unsaponifiable lipids :
- Do not react with alkali to form soap
- Present in relatively small amount. e.g.Fat solublevitamins, sterols, hydrocarbons,etc.

8. Based on Polarity
 Polar Lipids :
-Theyare chargedmolecules
- They are soluble in polar solvents like alcohol, acetone, etc.
- e.g. Phospholipids, glyceroglycolipids, fattyacids, etc.
 Non-Polar Lipids :
- Theyare unchargedmolecules
- They are soluble in non-polar solvents likeether,benzene,hexane, etc.
- e.g. Glycerides, sterols, sterol esters,Carotenoids, waxes,vitamins, etc.

9. Lipid Properties
 Lipids may be either liquids or non-crystalline solids at room
temperature.
 Pure fats and oils are colourless, odourless, and tasteless.
 They are energy-rich organic molecules Insoluble in water and
soluble in organic solvents like alcohol, chloroform, acetone,
benzene, etc.
 No ionic charges
 Solid triglycerols (Fats) have high proportions of saturated fatty
acids.
 Liquid triglycerols (Oils) have high proportions of unsaturated fatty
acids.

10. Lipid Functions
 They are stored forms of energy in all living organisms. Fat molecules
have maximum number of hydrogen atoms so, they have maximum of
electrons, which produce more energy as ATP
 They are structural components of the cell.
 In human body lipids are needed in the diet to solubilize the fat-soluble
vitamins like A, D, E and K.
 Lipids act as an insulating material, which prevents the dissipation of
heat from the body. 
 Lipids provide cushioning effect to the body which prevents the body
against mechanical injuries. 
 As lipids are insoluble, they generate no osmotic pressure when
stored in the cells.

11. References
 https://microbenotes.com/lipids-properties-structure-
classification-and-functions/#classification-types-of-lipids
 https://byjus.com/biology/lipids/
 Book- Food Chemistry by Fennama O. R

12.  Lipid Structure and Types :
https://www.youtube.com/watch?v=_ExVXeovB6s
 Lipid - Classification :
https://www.youtube.com/watch?v=dKT_9AjO9BE

13. Presentation Presented by
ATHARV KURHADE
2ND YR B.TECH FOOD TECHNOLOGY
MIT MIT-ADT UNIVERSITY, MIT COLLEGE OF FOOD
TECHNOLOGY, LONI-KALBHOR, PUNE

14. 😀😄