THE INFLUENCE OF AUTOXIDATION ON MILK-FAT COMPOSITION

The influence of autoxidation processes upon milk fat composition is d escribed. Time resolved changes in peroxide value (PV), ultraviolet ab sorbance, triglyceride contents and fatty acid composition are shown. Changes in PV and UV absorbance are compared and the great influence o f light on autoxidation is demonstrated. Within the investigated PV ra nge of about 0 to 2 no perceptible changes in triglyceride and fatty a cid contents were found with respect to accuracy of measurements. The rises in PV and UV absorbance cannot be correlated directly even for a single fat, but both parameters are increasing after an initial perio d. Exclusion of light nearly leads to inertness against autoxidation e ven at a temperature of 50-degrees-C. Long-term storage of milk fats w ill not affect milk fat parameters if samples are kept under nitrogen at -18-degrees-C in the dark. So application of a milk fat reference m aterial over a longer period is possible. Even beginning autoxidation will not implicitly affect e. g. the performance of foreign fat detect ion in milk fat by triglyceride analysis.