Monitoring of Pesticide Residues from Vine to Wine
Abstract
Those previous years, pesticides are often brought to the forefront by media. Questions arose about their toxicity for growers and consumers. Even if a downward trend is underway, the use of pesticides is required to ensure steady quality and quantity of harvests. A large number of active ingredients are authorized but regarding viticulture, mainly insecticides and fungicides are applied, to control pests and diseases and to increase crop yield. Some phytosanitary products, principally fungicides, applied close to the harvest date may frequently be detected in wines. Although no Maximum Residue Limits (MRLs) are set so far for the wine, powerful analysis methods have to be developed in order to detect low levels of compounds and prohibited molecules in particular. Moreover, organic winegrowers are concerned about contamination problems that may arise in the field or during the winemaking. In this work, a liquid chromatography – tandem mass spectrometry (LC-MS/MS) method is used to monitor about 190 pesticide residues. The extraction step is carried out either by QuEChERS (Quick, Easy, Cheap, Efficient, Rugged and Safe) or by SPE (Solid-Phase Extraction) for liquid samples. Optimisations were performed for the extraction of analytes from vine leaves (grinding, QuEChERS extraction and purification step) and validation parameters were controlled for different matrices (vine leaves, grapes, wines, lees) in terms of precision and accuracy. Several experiments were then conducted to monitor pesticide residues. For two vintages, vine leaves were analysed during the summer for a conventional plot as well as for an organic plot next to it. Sampling was done before and 48 hours after each phytosanitary treatment to evaluate contamination of the organic plot and the persistence of residues over time. Grapes, musts and wines were also analysed and when possible compared to the applied phytosanitary scheme to evaluate the persistence of compounds used in the vineyard. Sampling was also carried out all along the vinification process, from ripe berries to the wine during ageing in order to observe on one hand if contamination phenomena took place and eventually detect critical steps and on the other hand to estimate the transfer of active substances all along the process. Preliminary experiments were also conducted on the effect of alcoholic fermentation on pesticide residues at laboratory scale. Persistence and transfer are variable depending on molecules.
Issue: Macrowine 2016
Type: Poster
Authors
*Université de Bordeaux