Mass-marketed grapes can remain in storage for months and are usually treated with sulphur dioxide to prevent decay. Although the sulphur dioxide is effective, it is corrosive and can cause severe allergic reactions in some people. Wine-makers have a similar problem in that the sulphites added to wines to prolong their shelf-life and allow them to age can make their wines unpalatable to some drinkers.
Francisco Artes-Hernandez and his team at the Technical University of Cartagena in Spain compared several different preservative methods with a new technique that involves exposing macroperforated packages of grapes at 0 degress C to cycles of 0.1 micro liters per liter of ozone. They found that ozone treatment was 90% as effective as SO2 at preventing decay. In addition, ozone-treated grapes had up to four times more antioxidants than untreated grapes (Journal of the Science of Food and Agriculture, doi 10.1002/jsfa.2780).
It is not yet known why antioxidant levels increase, but because these compounds are up-regulated in response to environmental stress in plant cells, it could be that the ozone is perceived as a biochemical insult.
Andrew Waterhouse, Chair of the Department of Viticulture at University of California, Davis, said that because wine growers don't store grapes for prolonged periods, they are unlikely to use ozone in any preservation process. He agreed, however that the ozone process could be tweaked to replace problematic sulphites added to wine during the liquification process, presenting the possibility of healthier more hypoallergenic wines.
Source:Society of Chemical Industry