Fats and oils are the major part of the lipid present in the adipose tissue of mammals. Fats and oils are the esters of fatty acids and alcohols and on hydrolysis gives fatty acids and alcohols. Fats and oils are mainly the glyceryl esters of various fatty acids like palmitic, stearic, oleic, linoleic and linolenic. These are also called as triglycerides as three molecules of fatty acids condense with one mole of glycerol to form fat.

1. Mr. ANSARI SHOAIB AHMED
Assistant Professor
Department of Pharmaceutical Chemistry

2. INTRODUCTION
 Natural fats and oils are triesters of glycerol with long chain carboxylic acids(12-20
Carbon).
 These are known as triglycerides.
 Insoluble in water
 Saponifiable

3. INTRODUCTION
 Fats and oils are the major part of the lipid present in the adipose tissue of
mammals. Fats and oils are the esters of fatty acids and alcohols and on hydrolysis
gives fatty acids and alcohols. Fats and oils are mainly the glyceryl esters of
various fatty acids like palmitic, stearic, oleic, linoleic and linolenic. These are also
called as triglycerides as three molecules of fatty acids condense with one mole of
glycerol to form fat. For example

5.  Fats on hydrolysis by the enzyme lipases give corresponding fatty acids & glycerol. Fats
and oils are of two types
a) SIMPLE: When the three fatty acids of triglyceride are the same.
b) MIXED: When the three fatty acids of triglyceride are not identical.
 Natural fats are mainly mixed glycerides and they do not have free acid or base (groups)
so also known as neutral fats. Fats and oils are obtained from plants as well as animals.
For e.g. lard (pig fat), tallow (beef), coconut oil, castor oil, olive oil, soyabean oil, etc.
 Fats exist in animals under the skin and between muscular tissues.
 In plants, fats occur in seeds, and in fruits.
 A crude fat along with the glyceryl ester contains some amount of free fatty acids and 1-
2% of unsaponifiable matter like sterols.

6. DIFFERENCE BETWEEN FATS AND OILS
FATS
Solid triesters of glycerol at room
temperature
Higher melting point
Usually consist of saturated fatty acid.
Single bond in carbon chain
Animal source
More stable
OILS
Liquid triesters of glycerol at room
temperature
Lower melting point
Usually consist of unsaturated fatty
acid.
Double bond in carbon chain
Vegetable source
Less stable

7. REACTIONS OF
FATS & OILS

8. 1.HYDROLYSIS

9. SAPONIFICATION
(Alkaline Hydrolysis of Fat/Oil)

10. HYDROGENATION
(Reduction)
 Hydrogenation is a process that reduces unsaturated fatty acid content of
triglycerides by attaching hydrogen atoms at the point of unsaturation in the
presence of catalyst, usually nickel is used as a catalyst.
 Hydrogenation accomplishes two things:
1. Increases the melting point of oil or fat
2. Resistance to oxidation and flavour deterioration.
 Hydrogenation process depends on several parameters like Pressure,
temperature, catalyst, speed of agitation.

11. (Reaction)
(Example)

12. RANCIDIFICATION OF OILS
 When fats and oils are left exposed to moist air, they develop foul smell and sore
taste.
 They are said to have rancid.
 The rancidification is caused by two type of reactions:
1. Oxidative rancidification: Involves the oxidation of carbon-carbon double bond
in fats and oils to produce volatile carboxylic acids.
2. Hydrolytic rancidification: Involves the hydrolysis of one or more ester linkage in
fats or oils to produce original acid.

13.  Bacteria from air furnish enzymes that promotes these reactions.
 Antioxidants are added to many edible fats and oil products to retard
rancidification.

14. DRYING OF OILS
 When highly unsaturated oils are exposed to air, they undergo oxidation and
polymerization to form thin waterproof film.
 Such oils are called as drying oils and the reaction is called as Drying .
 Linseed oil (Linum usitatissimum.), which is rich in linolenic acid, is a common
drying oil used in oil based paints and varnishes.
 Non drying oils are either saturated or moderately unsaturated.

15. ANALYSIS OF FATS OILS
 Many analytical methods have been devised to have quality control over fats and
oils used as raw materials for the manufacture of soaps, drying oils and other
products.
 The two most important of these are determination of Saponification Number
and Iodine Number.

16. SAPONIFICATION NUMBER
(Saponification Value)
 Saponification number is defined as the number of milligrams of KOH required
to saponify one gram of a fat or oil.
 The saponification number tells the approximate molecular weight of a fat or oil.
 In the saponification reaction one mole of a fat reacts with three moles of a KOH
since the former has three ester groups.
 if M be the molecular weight of the fat, M grams of it requires 3×56=168 grams
or 168000 milligrams of KOH for saponification.
 Therefore,
𝑆𝑎𝑝𝑜𝑛𝑖𝑓𝑖𝑐𝑎𝑡𝑖𝑜𝑛 𝑛𝑢𝑚𝑏𝑒𝑟 =
168000
𝑀

17. IODINE NUMBER
(Iodine Value)
 Iodine number is the number of iodine that would add to carbon-carbon double
bonds (C=C) present in 100 grams of the fat or oil.
 The degree of unsaturation of a fat or oil is measured by its Iodine Number.
 Greater the number of double bond, greater the number of iodine will be added.
 I-Br (Iodine bromide) is used as a reagent.

18. ACID NUMBER
(Acid Value)
 Acid value (or neutralization number or acid number or acidity) is the mass
of potassium hydroxide (KOH) in milligrams that is required to neutralize one
gram of chemical substance.
 The acid number is a measure of the number of carboxylic acid groups in a
chemical compound, such as a fatty acid, or in a mixture of compounds.
 In a typical procedure, a known amount of sample dissolved in an organic solvent
(often isopropanol) and titrated with a solution of potassium hydroxide (KOH) of
known concentration using phenolphthalein as a color indicator.

19.  The acid number is used to quantify the acidity of a substance e.g. biodiesel.
 It is the quantity of base, expressed in milligrams of potassium hydroxide, that is
required to neutralize the acidic constituents in 1 g of sample.
𝐴𝑐𝑖𝑑 𝑁𝑢𝑚𝑏𝑒𝑟 =
𝑉𝐾𝑂𝐻 × 56.1 × 𝑁
𝑊 𝑜𝑖𝑙
• VKOH = Vol. of KOH consumed
• 56.1 = Mol. Wt. of KOH
• N = Normality of KOH (0.1 N)
• W = Wt. of oil/ fat
Therefore, the formula become;
𝐴𝑐𝑖𝑑 𝑁𝑢𝑚𝑏𝑒𝑟 =
𝑉𝐾𝑂𝐻 × 5.61
𝑊𝑜𝑖𝑙

20. ESTER NUMBER
(Ester Value)
 Ester value is the number of milligrams of KOH required to saponify the ester
present in 1g of the substance.
 Determine the Acid valve and saponification value of the substance under
examination.
 Calculate the Ester value from the expression:
Ester value = Saponification value – Acid value

21. ACETYL NUMBER
(Acetyl Value)
 Acetyl value is the number of milligrams of KOH required to neutralize acetic
acid produced by the saponification of 1g of completely acetylated fat or oil.
Formula:
𝐴𝑐𝑒𝑡𝑦𝑙 𝑣𝑎𝑙𝑢𝑒 =
1335 𝑏 − 𝑎
(1335 − 𝑎)
a = saponification value of a substance
b = saponification value of a acylated substance

22. REICHERT-MEISSL VALUE
(Reichert-Meissl Value)
 Reichert-Meissl value is the number of milligrams of 0.1N KOH required to
neutralize the water soluble steam or to neutralize distillate of 5g of hydrolysed
fat or oil.
 It is an indicator of how much volatile fatty acid can be extracted from fat through
saponification.
 It is a measure of volatile fatty acid residues present in a given fat or oil.

23. PRINCIPLE:
 For the determination of RM value, known sample is completely saponified with
alkali.
 The resulting solution is then acidified with dilute H2SO4 and then steam distilled.
 The distillate which contains the volatile acid is then titrated against 0.1N KOH
solution.

24. PROCEDURE:
1. To 10g of the sample, add an excess of 0.1 N NaOH solution in order to
completely saponify the fat.
2. Acidify the solution with dilute H2SO4 and proceed for steam distillation.
3. Titrate the distillate containing the volatile oil with 0.1N KOH solution using
phenolphthalein as an indicator.
4. Calculate the RM valve from the expression:
RM value =1.10 (T1-T2)
Where,
T1= Vol. of 0.1 N KOH consumed
T2= Vol. of 0.1 N KOH consumed for blank titration

25. SIGNIFICANCE:
1. RM value is used for testing the purity of butter and desi ghee which may
contain high amount of glycerides of butyric acid and other volatile fatty acid
residues. For example, adulterated butter has low RM value as that of pure
butter.
2. This RM value is an indicator of non-fat compounds in edible fats like butter and
ghee.