Measurement of Peroxide Value in Edible Oils and Fats, and in Foods by Rapid Coulometry

Rapid coulometry was developed for the rapid and sensitive measurement of peroxide value (POV) of edible oils and fats, and foods by using a carbon felt electrode with ferrocyanide ion as a mediator. The reaction mechanism is as follows: 1) iodine is formed by the reaction of iodide ion and peroxide in the sample, 2) the reaction of iodine and ferrocyanide ion produces ferricyanide ion, and 3) ferricyanide ion is electrochemically reduced within 25 sec at the working electrode, which is maintained at -0.4V vs. the counter electrode.It was possible to conduct 25 repeated injections of 5μl of sample solution. A linear relationship between charge and concentration of iodine was observed over the range of 5×10-5×10-2M which corresponded to a POV range of 1.3-446. The analytical results obtained by rapid coulometry were in good agreement with those by iodometry.