A scientific analysis of the fruit juice market has revealed the make-up of our favourite drinks.

Researchers at the University of Glasgow have completed the first comprehensive antioxidant study specific to fruit juices.

Alan Crozier, Professor of Plant Biochemistry and Human Nutrition, who conducted the study, said: 'Not all fruit juices are the same.

'The findings reveal that the variety of phenolic compounds and antioxidant capacity of the individual juices varied markedly.

'Purple grape juice made with Concord grapes contains the highest and broadest range of polyphenols as well as having the highest antioxidant capacity. Other high-ranking products include cloudy apple juice and cranberry juice drink.

'Supplementing a healthy diet with a regular intake of a variety of fruit juices such as purple grape juice, grapefruit juice, cloudy apple juice and cranberry juice, will, without major dietary changes, increase, both qualitatively and quantitatively, the consumer's intake of phenolic antioxidants.'

The study was carried out by the Plant Products and Human Nutrition Research Group at the University of Glasgow and features in the Journal of Agriculture and Food Chemistry. It is the first of its kind in the UK and provides a comprehensive analysis of polyphenols, which are strong antioxidants.

Professor Crozier said: 'Dietary polyphenols through their antioxidant properties, and possibly other mechanisms, are believed to play a role in protecting against chronic diseases.

"Phenolic antioxidants are bioactive compounds in fruits, vegetables and beverages that play an active role in the human body. By quenching free radicals they help maintain oxidative balance and are thought to play a key role in maintaining and improving health.'

As well as purple grape juice, the fruit juices examined in the study included cloudy apple, pomegranate, cranberry, grapefruit, clear apple, pineapple, orange, tomato, red grape and white grape.

This fruit juice specific study is of particular interest following the recent Kame project, which associated long-term fruit juice consumption with a reduced risk of Alzheimer's disease. The Glasgow study suggests these protective effects may be strengthened by consumption of a combination of juices with a high concentration and broad range of polyphenolic antioxidants.

The study findings also revealed the number and level of antioxidant phenolic compounds in purple grape juice equates with those found in a Beaujolais red wine

Ray McHugh (r.mchugh@admin.gla.ac.uk)

For further information or to speak to Professor Crozier, please contact Ray McHugh from Glasgow University Media Relations Office on 0141 330 3535 or email r.mchugh@admin.gla.ac.uk

First published: 15 March 2007