The contribution of phytochemicals to the antioxidant potential of fruit juices

This review highlights and discusses in vitro and in vivo evidence of the antioxidant activity of fruit juices, cocktails, and nectars, including traditional fruit juices such as apple, orange, and grape, but also anthocyanin-rich berry juices (i.e., blueberry, black currant, cranberry, strawberry, etc.) and exotic juices (i.e., pomegranate, passion fruit) that have come to be referred to as superfruit products. These juices are noted for characteristic polyphenolic secondary metabolites such as phenolic acids and flavonoids, comprised of flavones, flavonols, flavanones, flavanols, anthocyanins, and proanthocyanidins. These molecules play a key role in the antioxidant activity of the juices in addition to constituent bioactives such as l-ascorbic acid, carotenoids, xanthophylls, etc. The stability of polyphenol content and associated antioxidant activities to processing and storage are also discussed, as well as the bioaccessibility, bioavailability, metabolism, excretion and ultimately in vivo effects on indices of antioxidant status and oxidative stress are also addressed.