Stability of the antioxidant capacity of twenty-five commercially available fruit juices subjected to an in vitro digestion

Fruit juice is known to be rich in a variety of antioxidants, which may have protective effects against certain diseases. The objective of the present study was to analyse the total antioxidant capacity of twenty-five commercially available juices [via ferric-ion reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH)] and to determine the stability of the antioxidant capacity after an in vitro digestion procedure. All of the juices analysed were a significant source of antioxidants however there was wide variation between the different types of juice (1405-10232 μmol Fe^II L^-1, 30.5-84.8% inhibition of DPPH). Pomegranate juice had the highest antioxidant capacity compared to the other types of juice analysed (orange, apple, pineapple, grapefruit, red grape, cranberry). For many of the juices, the total antioxidant capacity was significantly (P < 0.05) enhanced after an in vitro digestion. In general, there was little difference in antioxidant capacity between premium brand and budget brand varieties of fruit juice.