Principles of Biochemistry (2+1)

6.4.5.4 Peroxide value

It is defined as the number of milliequivalents of peroxide per kilogram of fat.

The peroxide value gives an indication of the extent of oxidative rancidity. It is a measurement of the amount of oxygen absorbed at double bonds in unsaturated fatty acids contained in fish oil. Fresh oil usually has peroxide values of less than 1 meq/kg and may increase up to 10 meq/kg. Values of the order of 10 to 20 meq/kg usually indicate rancidity. The most common method of estimation is based on iodometric titration that measures the iodine liberated from potassium iodide by the peroxide present in the oil.