This document discusses fats and oils, including their reactions, properties, and analytical constants. It describes the processes of hydrolysis, hydrogenation, and rancidity. It also defines several analytical constants used to characterize fats and oils, such as acid number, saponification number, iodine number, ester number, Reichert-Meissl number, and acetyl number. The constants are used to identify fat composition and purity and to detect adulteration.

1. Amit Z Chaudhari
FATs & OILs

2. 2
I N T R O D U C T I O N
- Biomolecules,
- Fat is extracted from animal vegetables and liquid form is referred to
as oils
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3. R E A C T I O N S
1. Hydrolysis
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4. R E A C T I O N S
1. Hydrolysis
Soap solution – carboxylate salts
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5. R E A C T I O N S
1. Hydrolysis
Soap solution – micelle formation
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6. R E A C T I O N S
2. Hydrogenation
- mechanism:
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7. R E A C T I O N S
2. Hydrogenation
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8. R E A C T I O N S
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2. Hydrogenation
- E.g.
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9. P R O P E R T I E S
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1. Rancidity of oils
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10. P R O P E R T I E S
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1. Rancidity of oils
- Radical chain reaction of fat rancidity
1

11. P R O P E R T I E S
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2. Drying oils
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cobalt-catalyzed drying process

12. A N A L Y T I C A L C O N S T A N T S
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1. Acid number
Synonym: neutralization number, Acid value
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13. A N A L Y T I C A L C O N S T A N T S
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1. Acid number
Principle:

14. A N A L Y T I C A L C O N S T A N T S
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1. Acid number
1

15. A N A L Y T I C A L C O N S T A N T S
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2. Saponification Number
Synonym: Saponification value, Koettstorfer number
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16. A N A L Y T I C A L C O N S T A N T S
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2. Saponification Number
Principle
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17. A N A L Y T I C A L C O N S T A N T S
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2. Saponification Number
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18. A N A L Y T I C A L C O N S T A N T S
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2. Saponification Number
Significance:
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19. A N A L Y T I C A L C O N S T A N T S
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3. Iodine Number
Synonym: iodine value
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20. A N A L Y T I C A L C O N S T A N T S
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3. Iodine Number (iodine value)
Principle:
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21. A N A L Y T I C A L C O N S T A N T S
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3. Iodine Number (iodine value)
Significance:
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22. A N A L Y T I C A L C O N S T A N T S
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4. Ester Number (Ester value)
is the number of mg of KOH required to saponify the esters present
in 1 g of the substance.
Ester value = Saponification value - Acid value.
2

23. A N A L Y T I C A L C O N S T A N T S
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4. Ester Number (Ester value)
Method:
- Weigh accurately about 2 g of the sample. Add 25ml of 0.5M
ethanolic KOH
- And boiled under reflux condenser on a water-bath for1hour.
- Add 20ml of water and titrate the excess of alkali with 0.5 M HCl
using a further 0.2ml of phenolphthalein indicator.
- Repeat the operation without sample. (Blank reading)
- The difference between the titrations represents the alkali required to
saponify the esters.
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24. A N A L Y T I C A L C O N S T A N T S
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4. Ester Number (Ester value)
Significance:
Ester value = Saponification value - Acid value.
- The ester value shows the amount alkali consumed in the
saponification of the esters and is possible identify and differentiate
the fats with this value.
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25. A N A L Y T I C A L C O N S T A N T S
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5. Reichert-Meissl number [Reichert Meissl (RM) value ]
It is defined as the ml of 0.1 N KOH required to completely
neutralize the soluble volatile fatty acids distilled from 5 g fat.
- RM number is useful in testing the purity of butter since it contains a
good concentration of volatile fatty acids (butyric acid, caproic acid
and caprylic acid).
- Butter has a RM number in the range 25-30, while it is less than 1 for
most other edible oils. Thus any adulteration of butter can be easily
tested by this sensitive RM number.
2

26. A N A L Y T I C A L C O N S T A N T S
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5. Reichert-Meissl number [Reichert Meissl (RM) value ]
Principle:
- Fat is saponified using glycerol-alkali solution & acidified by
sulphuric acid to liberate free fatty acids.
- the liberated fatty acids are steam distilled and the steam volatile
fatty acids are collected (as condensate). The cooled condensate of
the volatile fatty acids is filtered for separation of water soluble and
water insoluble fatty acids.
- The water soluble fatty acids is titrated with alkali to give RM value,
- water - insoluble fatty acids is titrated to give the polenske value.
2

27. A N A L Y T I C A L C O N S T A N T S
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5. Reichert-Meissl number [Reichert Meissl (RM) value ]
Significance:
- It is a measure of water soluble steam volatile fatty acids chiefly
butyric and caproic acids present in oil or fat.
- No other fat contains butyric acid glycerides, and therefore, the
Reichert Meissl value of the butter fat is higher than that for any
other fat.
- These determinations have been used principally for analysis of
butter and margarines.
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28. A N A L Y T I C A L C O N S T A N T S
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6. Acetyl Number (Acetyl value)
is the number of mg of KOH required to acetic acid liberated by the
hydrolysis of 1 g of the acetylated substance.
Method:
- Boil the 10g of sample with 20 ml of acetic anhydride for 2 hr.
- Add 600 ml water and boil for 30 min.
- Separate and wash the acetylated product
- Determine the saponification value of the acetylated substance(b ml).
- Determine the saponification value of the substance(a ml).

29. A N A L Y T I C A L C O N S T A N T S
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6. Acetyl Number (Acetyl value)
Significance:
- Is the measure of hydroxy acids in lipids.
- Increased number of acetyl value indicates more amount of free fatty
acids.

30. of the topic
End
Reference:
Organic Chemistry– Morrison & boyd
Textbook of org. chem. – Bahl & Bahl
IP – 2010 vol.1
Web source