The assay of conjugable oxidation products applied to lipid deterioration in stored foods

Abstract

SummaryA new analytical procedure, determining oxidation products of polyenoic fatty acids, is applied to both fresh and stored foods and fats. the extent of deterioration of the extracted lipid is measured by changes in the ultraviolet spectrum resulting from the chemical reaction steps of the assay–the results are compared with the traditional peroxide value. In the assay not only hydroperoxides of polyenoic fatty acids but also hydroxy and carbonyl compounds derived from them, yield ‘conjugable oxidation products’ which are measured together and expressed as the ‘C.O.P. value’. At the same time an ‘oxodiene value’ independently determines the unsaturated carbonyl compounds. Another feature of the assay is that is distinguishes between the oxidation products derived from dienoic fatty acids and those of more highly unsaturated polyenoic fatty acids and this is measured by the ‘C.O.P. ratio’.For possible greater convenience in quality control, a quicker procedure is also described in which only the final spectrum derived from the conjugable oxidation products is measured.