Residue-free Wines: Fate of Some Quinone outside Inhibitor (QoI) Fungicides in the Winemaking Process VINCENZO LUIGI GARAU,* ,† SUSANA DE MELO ABREU, § PIERLUIGI CABONI, † ALBERTO ANGIONI, † ARMINDA ALVES, § AND PAOLO CABRAS † Dipartimento di Tossicologia, Universita ` di Cagliari, Via Ospedale 72, 09124 Cagliari, Italy, and LEPAE-DEQ, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto Portugal The fate of three fungicide residues (fenamidone, pyraclostrobin, and trifloxystrobin) from vine to wine was studied to evaluate the decay ratio and the influence of the technological process. The aim of this work was to identify pesticides that can degrade rapidly or be eliminated together with byproduct (lees and cake) of the winemaking process to obtain wine free of residues. The disappearance rate on grapes was calculated as pseudo-first-order kinetics, and the half-life (t 1/2 ) was in the range from 5.4 ( 1.9 to 12.2 ( 1.2 days. The mechanism of dissipation of the three quinone outside inhibitor (QoI) fungicides was studied using different model systems. It was observed that the main mechanism responsible for disappearance was photodegradation. For active ingredients (ai) the half-lives of fenamidone, pyraclostrobin, and trifloxystrobin were 10.2 ( 0.8, 20.1 ( 0.1, and 8.6 ( 1.0 h, respectively, whereas for formulation higher half-lives were observed when epicuticular waxes were present (from 13.8 ( 0.2 to 26.6 ( 0.1 h). After winemaking, fenamidone, pyraclostrobin, and trifloxystrobin residues were not detected in the wine, but they were present in the cake and lees. This was due to the adsorption of pesticide residues to the solid parts, which are always eliminated at the end of the alcoholic fermentation. The data obtained in these experiments suggest that these three active ingredients could be used in a planning process to obtain residue-free wines. KEYWORDS: QoI fungicides; model systems; residues; wine; grapes INTRODUCTION The main pests of vine are downy mildew (Plasmopora Viticola), powdery mildew (Uncinula necator), and gray mold (Botrytis cinerea). The pesticides mainly employed against these adversities belong to the chemical classes of acylaniline, triazol, and dicarboximides and have been commercially used since the 1970s. It was only in the 1990s that new fungicides, belonging to new chemical classes, became available. These compounds have a different mode of action compared to traditional fungicides. Trifloxystrobin (methyl (E)-methoxyimino-{(E)-R- [1-(R,R,R-trifluoro-m-tolyl)ethylideneaminooxy]-o-tolyl} ac- etate) and pyraclostrobin (methyl N-(2-{[1-(4-chlorophenyl)- 1H-pyrazol-3-yl]oxymethyl}phenyl) N-methoxy carbamate) are strobilurines (Figure 1) having activities, similar to that of natural strobilurines, that are quite significant against downy and powdery mildew. They act on the respiration process by blocking the transport of electrons within the mitochondria from cytochrome b to cytochrome c1 by binding to a specific site (1). Fenamidone ((S)-1-anilino-4-methyl-2-methylthio-4-phe- nylimidazolin-5-one) (Figure 1) is a pesticide active against downy mildew, belonging to the imidazolinone class, having * Corresponding author (e-mail vlgarau@unica.it; fax +390706758612). † Universita ` di Cagliari. § Universidade do Porto. Figure 1. Structures of fenamidone (1), pyraclostrobin (2), and trifloxy- strobin (3). J. Agric. Food Chem. 2009, 57, 2329–2333 2329 10.1021/jf8029572 CCC: $40.75  2009 American Chemical Society Published on Web 02/16/2009