A change in antioxidative capacity as a measure of onset to oxidation in pasteurized milk

The shelf-life of dairy products is the result of a delicate balance between the activity of anti- and pro-oxidants. During storage, an imbalance between the presence of reactive oxidants and the antioxidant defence mechanism can cause oxidation. The objective of this study was to investigate the added value of methods that measure the antioxidative capacity, such as the ‘Ferric Reducing Antioxidant Power’ (FRAP) and ‘Diphenyl Picryl Hydrazyl’ (DPPH) method, to monitor the sensitivity to oxidation in milk and to compare these methods with the more conventional peroxide value method measuring primary oxidation of the milk fat. For milk exposed to light, the antioxidative capacity of milk serum already decreased during the first days of storage, while the formation of lipid hydroperoxides was detected only after 7 days. Therefore, the FRAP and DPPH methods provide additional information on sensitivity to oxidation, resulting in a more comprehensive view on the concept of oxidation.