Occurrence of lipid oxidation compounds in commercialised functional dairy products

Oxidative stability of bioactive lipid-functional dairy products is essential to ensure their role in the prevention and/or treatment of certain diseases. The oxidation state of commercial functional dairy products, along with conventional dairy products, was evaluated at the acquisition and expiry dates. Functional dairy products containing omega-3 fatty acids (FPω3), conjugated linoleic acid (FPCLA) or stanol esters (FPSE) were tested. Quantitation of oxidised triacylglycerols, not applied so far to dairy products, was used as a measurement of primary and secondary oxidation compounds. Tocopherols and peroxide values were also determined. Conventional dairy products and FPSE showed high stability, in contrast to the relatively lower stability of FPω3 and FPCLA. FPω3 and FPCLA were significantly oxidised even at the initial date, and half of such samples oxidised further during the shelf-life period. However, while hydroperoxides were predominant in FPω3, polymer formation was found to be the early oxidation marker of FPCLA oxidation.