Evolution of tebuconazole residues through the winemaking process of Mencía grapes

The removal of tebuconazole residues during the winemaking process, applied initially to red must elaborated from Mencía variety grapes from A.O.C. Valdeorrras (Ourense, N.W. Spain), was studied. Analytical determination of tebuconazole residues in grapes, musts and wines were perfomed by gas chromatography equipped with an ion trap mass spectrometry detector (GC–ITMS). Tebuconazole is retained on the solid matter (cakes and lees) and clarification agent. The eliminated percentage of tebuconazole in the final wine is 86%. The influence of this fungicide on the fermentative activity of Saccharomyces cerevisiae yeast and the Oenococcus oeni was also studied through in vitro assays. Liquid chromatography equipped with triple quadrupole mass spectrometer (LC–MS/MS) was used to determine tebuconazole residues in synthetic must and wine used for in vitro assays. No effect on the alcoholic or malolactic fermentation was observed; and no degradation of tebuconazole originated by these microorganisms was registered.