Determination of peroxide value by the colorimetric iodine method with protection of iodide as cadmium complex

Abstract

AbstractImproved procedures of the Swoboda and Lea method for the determination of peroxide values (POV) of fats and lipids are presented. After oxidation of iodide to iodine with the sample for 5 min under an inert atmosphere, an excess of the iodide ion is immediately converted to cadmium complex for protection from atmospheric oxygen. The iodine is measured colorimetrically at 358 or 410 nm, and POV is calculated from the absorbance. This method permits the rapid determination of POV with a small amount of sample at a moderate cost using usual glasswares. For the analysis of lipids in biological materials or food products, the chloroform solution obtained by the Bligh and Dyer method is directly subjected to this procedure without evaporation of the solvent. Conversions between POV obtained by the different methods are discussed.