Fate of pesticides during the winemaking process in relation to malolactic fermentation.

The effect of red wine malolactic fermentation on the fate of seven fungicides (carbendazim, chlorothalonil, fenarimol, metalaxyl, oxadixyl, procymidone, and triadimenol) and three insecticides (carbaryl, chlorpyrifos, and dicofol) was investigated. After malolactic fermentation using Oenococcus oeni, which simulated common Australian enological conditions, the concentrations of the active compounds chlorpyrifos and dicofol were the most significantly reduced, whereas the concentrations of chlorothalonil and procymidone diminished only slightly. The effect of these pesticides on the activity of the bacteria was also studied. Dicofol had a major inhibitory effect on the catabolism of malic acid, whereas chlorothalonil, chlorpyrifos, and fenarimol had only a minor effect.