Antioxidants

[Guru]

Fruit juices - Rank UK juices by antioxidant action

A study at the University of Glasgow that evaluated fruit juices commercially available in the UK according to their antioxidant content could act as a spur to the category, as consumers seek dietary ways to remain in rude health.
According to a preview of the Expenditure and Food Survey, to published by the Department for Environment, Food and Rural Affairs in May, consumption of fruit juice rose 24 per cent in the UK last year to 366ml per person per week. Fruit juice was the only soft drink category to show significant consumption growth.

There is a high degree of consumer awareness of the term 'antioxidant' and its relation to health and well-being - even if many people do not understand the mechanism. The study, said to be the first of its kind in the UK, could encourage more people to include juices in their diet as a relatively minor change that could potentially have a role in avoiding chronic illness.

In particular lead researcher Professor Alan Crozier said his team's findings are relevant to consumers wishing to reduce their risk of age-related dementia, in the light of a study published last year that indicated long-term fruit juice consumption could help protect against Alzheimer's disease.

"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," explained Prof Alan Crozier.

The new study draws particular attention to the juice of Concord grapes, which came out on top in terms of highest overall antioxidant capacity and the highest and broadest range of polyphenols.

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."
Other top scorers were cloudy apple juice and cranberry juice.
Crozier and his team assessed the total phenolic content of 13 commercially available fruit juices and juice drinks deemed to be the most popular in the UK using the Folin-Ciocalteu assay.

The products were: Spray Classic Cranberry; Welch's Purple Grape; Tesco Pure Pressed Red Grape; Pomegreat Pomegranate; Tesco Pure Apple (clear); Copella Apple (cloudy); Tesco Pure Grapefruit; Tesco Value Pure Orange (concentrate); Tropicana Pure Premium Smooth Orange (squeezed); Tropicana Pure Premium Tropical Fruit; Tesco Pure Pressed White Grape; Tesco Pure Pineapple; Del Monte Premium Tomato.

Individual phenolic compounds were identified and quantified, and catechin content and degree of polymerization of proanthocyanidins were analyzed.

The main components in purple grape juice were flavan-3-ols, anthocyanins, and hydroxycinnamates, together accounting for 93 per cent of the total phenolic content. The results for the red grape juice were said to be equal to those for a Beaujolais red wine

Interestingly, white grape juice, mainly containing hydroxycinnamates, had the lowest total phenolic content.

Antioxidant activity, measured using the ORAC and FRAP assays, was said to be "in broad agreement" with total phenol content.

The study is scheduled for publication in a future issue of the Journal of Agriculture and Food Chemistry, and appears in the early online edition today.

References

Publication: Journal of Agriculture and Food Chemistry Doi: 10.1021/jf062970x S0021-8561(06)02970-0
Title: Evaluation of Phenolic Compounds in Commercial Fruit Juices and Fruit Drinks
Authors: William Mullen, Serena C Marks, and Alan Crozier

Publication: American Journal of Medicine 2006, 379, 464-475
Title: Fruit and vegetable juices and Alzheimer's disease: the Kame project
Authors: Dai Q, Borenstein A. R, Wu Y, Jackson J. C., Larson E. B.