Persistence And Degradation Of Fungicide During The Winemaking Process In Relation To Alcohol Fermentation

Grey mold, powdery mildew and downy mildew were the most common fungi encountered in vineyards control. Fungicides were widely used in the treatment of diseases of grapes for vinification. Chlorothalonil, procymidone and dichlofluanid were three fungicides which widely used on grape achieved good results. As the mainly raw material of wine, undesirable residues might remain on grape and they could be transferred to the wine.In the paper, the removal of chlorothalonil, procymidone and dichlofluanid residues during the winemaking process in relation to alcohol fermentation, applied initially to synthetic must and actual must, were studied. Analytical determination of three fungicide in musts were perfomed by gas chromatography equipped with electron capture detection (GC-ECD) after a QUECHERS extraction to isolate them from the samples. Chlorothalonil and dichlofluanid eventually disappeared entirely after alcohol fermentation. However, the eliminated percentage of procymidone was 8.49%, and most of residues (91.51%) still remained in the synthetic medium. In the actual medium, the eliminated percentage of procymidone was 9.28%, and 91.51% residues remained in the final wine. Degradation product was also detected with gas chromatography equipped with triple quadrupole mass spectrometry (GC-MS). The lost chlorothalonil had been transformed to glutathione S-conjugates with Glutathione(GSH).3,5-Dichloroaniline identifying as metabolite of procymidone in the final wine. Dichlofluanid was unstable to light, and some formed N,N-dimethyl-N’-phenyl-sulfamide(DMSA). But, most of dichlofluanid was hydrolysed rapidly in fermentation medium to get thiophosgene. Thiophosgene was rapidly hydrolysed by water to form COS or react with protein containing-SH,-NH,-OH which was associated with detoxification. In the end, the degradation reaction mechanism of three fungicides had been studied using Gaussian 09W software. The results contributed to the knowledge of the metabolic pathway of three fungicides during wine-making.