UWS experts uncork the secret to disease-fighting wine

Date: 30/06/2002

We know a glass of wine a day can help keep the doctor away, but now researchers at the University of Western Sydney are making the humble glass of red even healthier.

Dr Geoffrey Skurray and PhD student Steven Clare from the Centre for Advanced Food Research are finding ways to boost the levels of antioxidants in our wine to better protect us from coronary heart disease and cancer.

They've discovered that simple techniques carried out in the winemaking process can actually increase the amount of these disease-fighting compounds in your favourite bottle of red.

"Wine is rich in antioxidants - compounds which have been shown to help prevent heart and vascular disease, cancer and other degenerative conditions," says Mr Clare.

"One of these antioxidants, resveratrol, is naturally found in high concentrations in grape skins.

"We're investigating the relationship between the use of pectolytic enzymes in the fermentation process and the levels of resveratrol extracted from the skins.

"Our study shows that by employing pectolytic enzymes at the maximum recommended dosage to a batch of grapes the level of resveratrol can be increased by 37%."

Mr Clare says the beauty of this discovery is that winemakers don't have to change their production methods to give significant health benefits to drinkers.

"Adding pectolytic enzymes is a technique that red winemakers already employ to aid the fermentation process and enhance the level of red colour extracted from the grapes," says Mr Clare.

"The sensory qualities of red wine are derived by leaving the grape skins in contact with the juice during fermentation. Adding the enzyme to the fermenting grapes helps to break down the grape skin cell wall and extract the colour.

"Many winemakers wouldn't be aware that adding the enzyme for colour production can also significantly increase the level of resveratrol if added in higher dosages, and therefore improve the health benefits of their wine."

Mr Clare says the results from the current study show that increased resveratrol levels were evident only after the grapes had undergone pressing.

"The study showed that there was little change in resveratrol levels during fermentation and the free-run stages," he says.

Mr Clare says the challenge is to ensure that increased antioxidant levels don't compromise the wine's mouthfeel.

"The pressing stage has to be to carefully controlled, because although increased pressure can result in enhanced colour and antioxidant levels, it also increases the level of tannin - too much of which can render the wine undrinkable," he says.

"We have to ensure that any modification to the traditional winemaking process does not affect the overall quality of the wine."

Mr Clare says the next step is to ensure the resveratrol levels are maintained throughout the winemaking process.

"We are investigating different contacting methods, the use of fining agents and the ageing process with respect to their impact on resveratrol levels," he says.

"We hope the various compounds in wine responsible for good health can be increased and preserved in winemaking practices.

"Ultimately we'd like to see total phenolic (antioxidant) levels clearly labelled on wine bottles so consumers can make an informed health choice about the wines they drink."

Steven Clare is presenting his findings at the 27th Annual Meeting of the American Society for Enology and Viticulture Eastern Section Conference in Baltimore, Maryland in July.

For more information or requests for interviews:
Amanda Whibley
Media Officer
Phone: 9678 7472
Mobile: 0418 438 399
Email: a.whibley@uws.edu.au