Transcription: Estimation of Iodine Value of Fats and Oils - Amrita University - YouTube

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Estimation of Iodine Value of Fats and Oils Iodine value is the measure of the degree of unsaturation in fats and oils.

Iodine number or value is defined as the number of grams of iodine consumed by 100g of fat.
The principle behind the reaction is the addition of halogens like iodine to the double bonds present in the unsaturated fat.

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The iodine monochloride reagent is allowed to react with fat in the dark.

The amount of iodine consumed is then determined by titrating the iodine released on adding potassium iodide with standardized sodium thiosulphate solution and comparing it against the contents.
In the iodination flask labeled ‘Blank’.
Materials Required Iodine, Monochloride Reagent Potassium Iodide 0.

1, Normal Sodium thiosulphate Starch indicator solution.
Reagent bottle Chloroform Fat sample in chloroform, Iodination, flask, Burette and burette stand with magnetic stirrer Glass, pipette Measuring cylinder, Distilled water Procedure, Arrange all the required materials on the table.
Pipette out 10 ml fat sample from a 2 % fat solution prepared in chloroform into an iodination Flask labeled ‘Test’.

Stopper, the flask.
Pipette out 20 ml iodine monochloride reagent into the flask labeled ‘Test’.
Stopper, the iodination flask.

Swirl, the flask to mix the contents.
This flask is then kept in the dark for incubation at room temperature for 30 minutes.

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Meanwhile, prepare the blank sample by pipetting out 10 ml chloroform in an iodination flask labeled ‘Blank’.

Pipette out 20 ml iodine monochloride reagent to the flask labeled ‘Blank’.
Stopper, the iodination flask.
Swirl, the flask to mix the contents.

The flask labeled ‘BLANK’ is then kept in dark for incubation at room temperature for 30 minutes.
Take out the flask labeled ‘TEST’ after 30miutes incubation.
Pipette out 10 ml potassium iodide solution into the flask labeled ‘TEST’.

Stopper, the flask and gently swirl it to mix the contents.
Well, On mixing the color of the solution in the iodination flask changes to dark red brown Rinse, the stopper of the flask, with 30 ml, distilled water and mix the contents again.
The contents of the flask labeled ‘Test’ is then titrated against 0.

Sodium thiosulphate.
Continue the titration till the solution turns to pale straw, colour.
Now close the stop cock of the burette.

Add 1 ml of starch solution into the flask.
The color of the solution in the flask changes to purple blue.
Titration is continued until the color of the solution in the flask turns colourless.

The disappearance of the blue colour is recorded as the end point of the titration.
The procedure is repeated for the flask labeled ‘Blank’.
Pipette out 10 ml potassium iodide solution into the ‘Blank’ after 30 minutes incubation.

Stopper, the flask and swirl it to mix the contents.
Well, On mixing the color of the solution in the iodination flask changes to dark red brown Rinse, the stopper of the flask, with 30 ml, distilled water and mix the contents again.
The contents of the flask labeled ‘Blank’ are then titrated against 0.

Sodium thiosulphate.
Continue the titration till the solution turns to pale straw, colour.
Now close the stop cock of the burette.

Add 1 ml of starch solution into the flask.
The color of the solution in the flask changes to purple blue.
Titration is continued until the color of the solution in the flask turns colourless.

The disappearance of the blue color is recorded as the end point of the titration.
The volume of Sodium thiosulphate used is obtained from the titre values.
( [ Blank- Test ] ml ).

The Iodine value can be calculated using the formula Iodine value, =Equivalent Weight of Iodine * ( volume of sodium thiosulphate used, ) * Normality of sodium thiosulphate *.
100*.
10-3, Weight of fat sample used for analysis, [ g ], Where Equivalent Weight of Iodine is 127 and normality of sodium thiosulphate is 0.

Precautions.
Iodine monochloride is caustic.
, So handle the reagent with gloves.

For better results perform the experiments without any time gap during titration.
As the liberated iodine is susceptible to oxidation by light .


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