Comparison of the polyphenolic composition and antioxidant activity of European commercial fruit juices

Thirty six commercial European fruit juices were tested to ascertain their antioxidant capacity and polyphenolic composition. Six of the products were labelled 100% pomegranate juice, the others included 20 brands of diluted pomegranate juice or pomegranate blended with other fruit juices and 10 different non-pomegranate fruit juices. The antioxidant capacity of all the juices was determined while anthocyanin, ellagitannin and ellagic acid profiles of the 26 pomegranate juices and pomegranate juice blends were obtained using HPLC-PDA-MS2. Additional analysis was conducted on seven of the juices using HPLC with an on-line antioxidant detection system. Three of the "pure" pomegranate juices had the highest ellagitannin content and the highest antioxidant capacity. Only one of these three juices was rich in anthocyanins. The other "pure juices" had differences in their HPLC "pomegranate" fingerprint and also had a lower antioxidant capacity, in some cases lower than that of some of the blended juices. Vitamin C rather than phenolic compounds was the major contributor to the antioxidant capacity for some of the juices. Statistical analysis of both the antioxidant assay and the HPLC on-line antioxidant data demonstrated that the ellagitannins were the major antioxidants in the pomegranate juices. The complexity of the polyphenolic profile of pomegranates necessitates the use of HPLC-PDA-MS2 for a thorough evaluation of juice composition and authenticity.