Free radicals have been implicated in the initiation and progression of a number of diseases including various cancers, CVD and diabetes. Antioxidants are known to protect tissues against the damaging effects of oxygen-free radicals. Therefore, it has been hypothesised that a diet rich in antioxidants may infer protection against certain diseases. Fruits and vegetables are a major source of antioxidants among other bioactive compounds essential for optimal health. Current government recommendations promote the consumption of any five portions of fruit or vegetables per day in order to facilitate good health. However, though lacking in the fibre content of whole fruits, fruit juices are an excellent source of antioxidants. The objective of the present study was to analyse the total antioxidant capacity of a variety of fruit juices and to determine the stability of the antioxidant capacity after an in vitro digestion procedure.
Ten commercially available fresh fruit juices (both Tesco own brand and premium brand varieties) were selected. Samples of each juice were subjected to an in vitro digestion procedure(Reference Ryan, O'Connell and O'Sullivan1) designed to simulate in vivo digestion. The total antioxidant capacity of the samples was analysed prior to digestion via FRAP(Reference Benzie and Strain2) and the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay(Reference Brand-Williams, Cuvelier and Berset3). Following digestion samples were analysed via FRAP only.
n 3 independent experiments;
* P<0.05=significantly different to FRAP values prior to digestion.
All of the juices analysed were a significant source of antioxidants; however, there was wide variation between the different types of juice. Pomegranate juice had the highest antioxidant capacity compared to the other types of juice analysed. 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 supermarket own brand and premium brand varieties of fruit juice.
