Materials Required

• Fat/oil sample
• Analytical balance
• Hot plate
• Beaker
• Burette
• Conical flasks
• Measuring cylinders
• Acetic acid-chloroform solution (3:2 ratio)
• Saturated Potassium iodide (KI) solution
• 0.1 N Sodium thiosulfate standard solution
• 1% Starch indicator solution

Methods

1. Take fat/oil sample and in case of fat sample melt it by heating to its melting point using hot plate.
2. Weigh 5 g of sample in a conical flask.
3. Add 30 ml of acetic acid- chloroform solution in the sample flask.
4. Add 0.5 ml saturated KI solution and shake it for 1 min.
5. Then add 30 ml distilled water to the sample conical flask.
6. Titrate the mixture against 0.1 N sodium thiosulphate solution until yellow color is almost disappeared.
7. Add 0.5 ml of 1% starch solution shake vigorously
8. Titrate again carefully till the blue color just disappears.
9. Record the volume of sodium thiosulphate solution used.
10. Calculate the peroxide value using the equation given below:

Where,
S= volume of sodium thiosulphate used (ml)
N= Normality of sodium thiosulphate
W= weight of sample (gm)

11. Estimate oxidative rancidity of sample on the basis of determined peroxide value.