Pesticide removal in wine with a physical treatment by molecular sieving

Abstract

All along the winemaking process, conditioning and aging, wine is susceptible to be contaminated by different molecules. Contaminations can have various origins, related to wine microorganisms or as a result of an exogenous contamination. The aforementioned contamination of the wine can be caused by the migration of molecules from the materials in contact with the wine or by a contamination from exogenous molecules present in the air. Regardless of the source of the contamination, mainly two types of consequences can be observed. First, it could be a risk of organoleptic defects resulting in a loss of the wine quality and a deep change in its typicity. Second contaminants may be harmful on human health. Beyond these aspects, with the emergence of regulations and commercial requirements, these contaminants can also influence negatively the commercial image of the contaminated wine. Among the exogenous contaminants of the wines, pesticides are the family molecules on which the general public is conversant about. Even if there is no proven toxicological risk associated with the presence of pesticide residues in the wines, this issue is a major concern for consumers and producers. Recently several articles were published in France and indicated a widespread contamination of wines from conventional or organic wines. These articles also highlight the lack of official Maximum Residue Limit for wine. It is also reported that, among the residues detected, many molecules are possible or probable carcinogens, toxic for the development or the reproduction, endocrine disruptors or neurotoxic. Few physical processes are currently available to remove pesticide residues from wine. Based on that observation, the objective of this study was to evaluate the ability of a new physical treatment of wine by molecular sieving with Zeolites to remove pesticide residues. Zeolites are already widely used in water or air treatment applications. Natural Zeolites are low cost abundant resources. These are crystalline aluminosilicates. One of the main characteristics of these solids is the development of regular pore size in the microporous domain. According to their preparation, they have physicochemical properties such as cation exchange, molecular sieving, catalysis, and adsorption. This article describes the selection of a Zeolite able to remove a great variety of pesticides used in vine growing. The results of a treatment trial done on a red wine contaminated with 21 pesticides frequently detected in wines are also presented. All the molecules are removed with an elimination yield higher than 90%. Their removal is influenced by the Zeolite concentration. Our first trials also indicate no influence of such a treatment on red wine key physico-chemical parameters and aromas. Further tests will be performed on other types of wine and the influence of Zeolites treatment on the perception of winetasters will be investigated.