Quantification of Conjugated Dienes in Oxidizing Oils and Emulsions

UV spectroscopy is a simple method to detect and quantify hydroperoxides containing conjugated diene structures obtained from the oxidation of lipids containing linoleic and linolenic fatty chains. The protocol detailed below can be applied to the extracted dietary lipids, oil-in-water emulsions, and biological matrices stabilized by proteins. The UV spectra of the lipids solubilized in 2-propanol are recorded, and the absorbance at 233 nm is converted into molar concentration of conjugated diene hydroperoxides using their molar extinction coefficient. In addition to this classical approach, we recommend correcting the data using a nonoxidized blank sample selected by checking the second derivative of the UV-visible spectra.