2613
J. Agric. Food Chem. 1995, 43, 2613-2615
Fate of Some Insecticides from Vine to Wine Paolo Cabras,*lt Vincenzo L. Garau,+Filippo M. Pirisi,t Mario Cubeddu,* Franco Cabitza,' and Lorenzo Spaneddat Dipartimento di Tossicologia, Universita di Cagliari, Viale Diaz 182,09126 Cagliari, Italy, Centro Regionale Agrario Sperimentale, Vide Trieste 111,09123 Cagliari, Italy, and Dipartimento di Economia dell'Impresa, della Tecnologia, dell'hbiente, Universita di Cagliari, Vide Fra' Ignazio 74,09123 Cagliari, Italy
The fate of residues of five insecticides (chlorpyrifos methyl, fenthion, methidathion, parathion methyl, and quinalphos) from the treatment on vine to the production of wine was studied. The influence of clarifying agents (bentonite, charcoal, potassium caseinate, gelatin, polyvinylpolypyrrolidone, and colloidal silicon dioxide) on residue concentrations in wine was also studied. The insecticide residues on grapes showed high decay rates afier treatment, with first-order kinetics and half-lives ranging from 0.97 to 3.27 days. Grape processing into wine caused considerableresidue reduction ('80%) for chlorpyrifos methyl, parathion methyl, and quinalphos, moderate reduction (ca.50%)for methidathion, and almost no reduction for fenthion. The wine-making technique (with or without maceration) had the same influence on the residue concentrations in wine. The clarifying agents tested showed no or moderate influence on the residue contents in wine with the exception of charcoal, which allowed complete o r almost complete elimination of insecticide residues.
Keywords: Insecticides; residues; wine-making The grape moth (Lobesia botrana) is the most widespread and harmful parasite of grapes, after cryptogams such as downy mildew (Plasmopara viticola), powdery mildew (Uncinula necator), and gray mold (Botrytis cynerea). Usually, during one life cycle this insect can reproduce itself three times, but when environmental conditions are favorable (which is quite frequent in the south of Italy), a fourth generation can be reached. This fact leads to the need for pesticide treatments as near as possible t o harvest. Since the amount of residues is greatly affected by the preharvest interval, high residues could be present on grapes a t harvest time, especially when the active ingredient (ai) applied shows high stability. Consequently, high residues could also be present in wine if the effect of the wine-making technique on residue reduction is poor. Fungicide residues on grapes and their fate during wine-making have been widely investigated. In the current literature there are numerous papers that give a sufficiently clear picture of the residues of the most extensively used fungicides in grapes and wine. Moreover, the results of studies carried out in this field are reported in some recent reviews (Cabras et al., 1987; Flori and Cabras, 1990;Zironi et al., 1991;Farris et al., 1992). On the other hand, since data on insecticide residues in grapes and wine are quite limited, further studies are needed. This paper aims to contribute to the knowledge of the fate of five insecticides (chlorpyrifos methyl, fenthion, methidathion, parathion methyl, and quinalphos) from vine to wine. The persistence of these active ingredients in grapes, their behavior during wine-making (with the simplest technique, Figure l), and adsorption by the most widely used clarifying substances were studied. Dipartimento di Tossicologia.
* Centro Regionale Agrario Sperimentale. +
5 Dipartimento di Economia dell'Impresa, della Tecnologia, Dell'Ambiente.
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pressing and stemming
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dripping
1 vinification with maceration
vinification without maceration
i
1
Figure 1. Wine-making scheme.
EXPERIMENTAL PROCEDURES Materials and Methods. The trial was carried out in a red grape vineyard (cv. Cannonau),located at Ussana, near Cagliari, Italy. A random-block scheme was used, with four replications for each test, and each block contained 100 plants. Treatments were carried out on September 1, 1994; the insecticides were applied (6 hLha) with an F-320portable motor sprayer (Fox Motori, Reggio Emilia, Italy). The following commercial formulations were used at the doses recommended by the manufacturers: Tumar (containing 22.1% chlorpyrifos methyl),150 g/hL; Lebaycid (24.4%fenthion),250 g/hL; SupracafTaro (19% methidathion),200 g/hL;Polisar (16% parathion methyl), 200 g/hL; Ekalux (25% quinalphos), 150 g/hL. Samplings started about 1 h after treatment (on dry plants): random 5-kg samples of grapes were collected from each plot and analyzed immediately for insecticide residues. The samplings and analyses were repeated 1, 5, and 7 days after treatment. The environmentalconditions were continuously recorded with an AD-2 automatic weather station (Silimet,Modena, Italy). During the experiments there was no rainfall and maximum and minimum average temperatures were, respectively, 28.5and 15.8 "C. Wine-Making. After residue analysis, all four grape samples per ai (ca. 20 kg) were pressed and stemmed together (Figure 1);200 mg of sodium metabisulfite and 200 mg of dry yeast per kilogram of grapes were added, and the mixed sample was divided into two equal parts. One part was allowed to ferment with the skins (vinificationwith maceration); the other was dripped, and the resulting must was allowed to ferment (vinificationwithout maceration). A 100-g aliquot of cloudy must was taken and centrifuged at 4000 rpm
0021-8561/95/1443-2613$09.00/00 1995 American Chemical Society
2614 J. Agnc. Food Chem., Vol. 43, No, 10, 1995
Cabras et al.
Table 1. Residues (Parts per Million f SD) of Insecticides in Grapes, Must, and Wine grapes days after centrifuged insecticide treatment must must chlorpyrifosmethyl 0 0.16 f 0.07 0.06 0.02 1 0.06 f 0.02
