Influence of Quinoxyfen Residues on Saccharomyces cerevisiae Fermentation of Grape Musts

The effect of Quinoxyfen, a new pesticide against powdery mildew, on the fermentation of Saccharomyces cerevisiae has been evaluated. When vines (Montepulciano d'Abruzzo, Trebbiano and Sangiovese) were treated with doses recommended by the producer (30 mL/hL of a suspension concentrate 250 g/L), Quinoxyfen was detected up to the concentration of 0.014 mg/L in the must. The S. cerevisiae growth parameters, mu(max) and lag phase, were not affected by this residual level during fermentation. However, in must fortified with Quinoxyfen to obtain the concentrations of 0.5, 1.0, 2.0 mg/L, a decrease in the lag phase was observed. The fermentation kinetics did not show any significant differences between the different treatments and control musts. Moreover, the production of volatiles during fermentation, determined with solid phase microextraction - capillary gas chromatography (SPME-GC), was not affected by the residual level of Quinoxyfen. Principal component analysis (PCA) showed that the samples could be clustered according to the different yeast strains, regardless of the pesticide treatment.