This is for Bachelor of Pharmacy 3rd semester students that cover the chapter fats and oils. This is useful and also help them to prepare for examination.

1. Ms. Chandrika Sidar
M.Pharm [Pharmaceutical chemistry]
Assistant Professor, TIPR, Bilaspur
(C.G)

2. Fats and oils
 Fats and oils are type of lipids.
 Lipids – esters of fatty acid with alcohol.
 Fats and oils are composed of molecules known as
triglycerides, which are esters composed of three fatty
acid units linked to glycerol.

3. Structure of fats and oils (Triglycerides)
3 OH groups in glycerol esterifies with 3 moles of CA -Triglycerides

4. Occurrence of fats and oils
• Stored large amount of fats
in seed, roots and fruits.
• EX. Cotton seed oil, coconut
oil, castor beans , olive oils
have high fat contents.
Plants
• Fats deposits are to be found
under skin and around intestine
and kidneys.
• EX. Lard, tallows ( fats of kettle's)
Animals

5. Extractions of fats and oils
 Pressing- Seeds are crushed b/w steel rollers.
 Rendering- Animal tissues containing fat-chopped
and heated dry or with water until it melts.
 Solvent extraction- Residues after pressing undergo
solvent extraction with petroleum ether or benzene.

7. Classification of glycerides
SIMPLE GLYCERIDES
When 3 OH groups of
glycerol are esterified with
same acid.
MIXED GLYCERIDES
When 3 OH groups are
esterified with different
acid.

8. Differentiate between fats and oils
Fats Oils
Fats are solids or semisolids at room
temperature
Oils are liquids at room temperature
Fats contains large amount of saturated
fatty acids e.g. stearic and palmitic acids
Oils contains large amount of
unsaturated fatty acids e.g. oleic acid
Fats melt at high temperature Melt at low temperature
Fats do not contain double bonds Oils have double bonds
Fats are more stable Oils are less stable
Fats are animal fats Oils are vegetable fats
Ex. lard Ex. Olive oil, coconut oil

9. Physical Properties of Fats and Oils
 Pure fats and oils are colorless, odorless, and tasteless
 The characteristic colors, odors, and flavors that we
associate with some of them are imparted by foreign
substances that are lipid soluble and have been
absorbed by these lipids.
 Fats and oils are lighter than water, having densities of
about 0.8 g/cm3
 Insoluble in water but soluble in organic solvents such
as benzene, chloroform, ether etc.

10. Reactions of fats and oils
 1. Hydrolysis – Fat easily undergo hydrolysis when they boiled with
NaOH/KOH and ester linkage breaks gives glycerol and sodium salts of
long chain. Long chain of fatty acid are called soap and the process is
called saponification.

11.  2. Hydrogenation – unsaturated oils are converted into saturated
fats by passing hydrogen under pressure by using catalyst at high
temperature results formation of solid fats at room temp. and this
process also called hardening.

12.  3.Hydrogenolysis-This is a cleavage reaction in which fat or oil
molecule is treated with excess of hydrogen under pressure in presence
of copper-chromium catalyst. In this reaction fat or oil gets splits up
into glycerol and higher aliphatic alcohols.

13.  4.Rancidification: It is process of complete or incomplete
oxidation or hydrolysis of fats and oils when exposed to air, light, or
moisture or by bacterial action, resulting in unpleasant taste and odor.
Rancidity reactions may be due to hydrolysis of ester bonds (hydrolytic
rancidity) or due to oxidation of unsaturated fatty acids (oxidative
rancidity).
 5.Drying oils: A drying oil is the oil that hardens to a tough, solid
film after a period of exposure to air. The oil hardens through a
chemical reaction in which the components crosslink (and hence,
polymerize) by the action of oxygen (not through the evaporation of
water or other solvents). Drying oils are a key component of oil paint
and some varnishes. Some commonly used drying oils include linseed
oil, poppy seed oil, and walnut oil. Drying oils (wild rose oil, linseed oil,
wheat oil) contain more than 50% of polyunsaturated acids. They are
quickly absorbed and leave no greasy layer on oily skin. Their light
consistency makes them a good make-up primer.

14. Analytical constant of fats and oils
a) Acid value: The Acid value is the number, which expresses in milligrams, the
amount of potassium hydroxide necessary to neutralize the free acids present in
one gram of the substance (fats or oil).
Procedure: weigh accurately amount of fat or oil in C.F
Add 50 ml of ethanol-ether solution and shake well
Titrate the solution with KOH solution and phenolphthalein indicator
end point-pink colour
Formula : Acid value - 56.1 X V X N
W
Significance: quality of fat or oil or storage condition checked.
Acid value indicates the degree of rancidity of the given fat. High acid values arise in rancified oils.

15. b) Saponification value: Saponification value is defined as the number
of milligrams of potassium hydroxide required to completely saponify one
gram of fat or oil.
Procedure: Take 2g of sample in C.F fitted with reflux condensor
Add 25 ml of alcoholic KOH
Boil under waterbath for 1hr ( absence of oily matter)
Add 1 ml of phenolphthalein indicator and titrate with excess KOH with
0.1 N HCl solution , also carry out blank titration
Formula : Saponification value – 56.1 x (B-T) x N
W
Significance: gives an idea about the MW of fats and oils.
smaller the saponification value, higher the MW

16. c) Ester value: The Ester value is the number of milligrams of
potassium hydroxide required to react with esters present in 1 g of fat or
oil. The difference between saponification value and acid value is called
Ester value.
Formula : Ester value = Saponification value – Acid value
Significance: Higher the ester value indicates the presence of high
amount of ester and LMW fatty acid content.
d) Iodine value: Iodine value is defined as the number of grams of
iodine taken up by 100 gm of fat or oil or it is the number of grams of
iodine which will combine with 100 gm of the fat or oil.
Procedure: Hubl’s method: Fat or oil sample is dissolved in carbon
tetrachloride and is treated with excess of standard solution of ethanolic
iodine in presence of mercuric chloride. Unused iodine is then calculated
by titration with standard sodium thiosulphate solution.
Formula : Iodine value = 12.69 × (b-a) x N/W
Significance : Higher iodine value highly unsaturated the given fats.

17. e)Acetyl value: It is defined as the number of milligrams of potassium
hydroxide required to neutralise acetic acid produced by the
saponification of one gram of completely acetylated fat or oil.
Procedure: Fat/oil sample + 5ml of acetic anhydride/pyridine mixture+
5ml of water
put on boiling water bath for 30 min and cool
Titrate with 0.5 N KOH solution using phenolphthalein as an indicator
Formula : Acetyl value- 1335 x (b-a) / 1335-a
a= saponification value of oil/fat
b= saponification value of acetylated substance
Significance : greater acetyl value indicates more amount of free fatty
acid.

18. f) Reichert-Meissl value (RM Value)- It is no. of mg of 0.1 N aq
NaOH solutionn required to neutralise steam volatile water soluble fatty
acids distilled from 5g of oil/fat.
Procedure- 10g sample + excess of 0.1 N NaOH solution
Solution is acidified with dil.H2SO4 and undergo steam distillation
Distillate containing volatile acid and titrate with 0.1 N NaOH solution
using phenolphthalein indicator
Formula – RM Value= (A-B) x N x 11
Significance- Low R.M value means a low quality of butter or desi ghee.