First Application of Ozone Postharvest Fumigation to Remove Smoke Taint from Grapes

Abstract

Smoke taint is becoming a worldwide problem for wine production because of the increasing number of fires in wine regions. It is the result of volatile phenols released by fire smoke which bind to berry sugars, translocate mainly through bunch stem and/or through berry skin. The techniques used to remove smoke taint from wine can modify wine quality provided that smoke taint is completely removed from the wine. We report the first data on the ozone fumigation of harvested grape which was affected by the smoke taint. The experiments were run on table grapes in the laboratory. The grape bunches were smoked by straw fire for 2 hours and then ozone fumigated for 4 hours in a cold room at 10 °C. At a nonformal sensory evaluation, the smoke taint which was strong on smoked grapes, was not perceived after the ozone treatment, and the main volatile phenols (guaiacol and 4-methylguaiacol) of the smoke taint were reduced significantly; the skin color slightly darkened in the berries affected by smoke while skin firmness increased; ozone did not recover these effects. Application of NIR-AOTF (Near InfraRed-Acoustic-Optic Tunable Filter) and E-nose (electronic nose) on smoked grapes emphasizes the role of temperature but overall discovers the usefulness of the E-nose in the early detection of smoke taint.

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