Changes in the volatile composition of wine from grapes treated with Bordeaux mixture: a laboratory-scale study

Abstract

Background and Aims: We investigated the effect of the application of Bordeaux mixture in the vineyard on the copper concentration in the must, and the consequences for the volatile composition of wine.Methods and Results: Musts from grapes cv. Vinhao treated with Bordeaux mixture or with a triazole-based fungicide were prepared at a laboratory scale. Copper concentration decreased from 31.4 to 12.6 mg/L during fermentation, as determined by atomic absorption spectrometry. Increased copper concentration promoted a significant decrease in the concentration of higher alcohols, including isoamyl alcohol, and of esters of organic acids, including ethyl lactate, as determined by liquid-liquid microextraction Gas chromatography (GC)-flame ionisation detection and solid phase extraction GC-ion trap-mass spectrometry (MS) analysis. In contrast, the concentration of acetates such as ethyl acetate increased sharply, together with terpenes, namely linalool.Conclusions: The treatment of grapes in the vineyard with Bordeaux mixture shifted the aromatic composition of wine.Significance of the Study: Besides its scientific importance, the elucidation of how Bordeaux mixture affects grape and wine quality is of significant interest in oenology, especially in organic viticulture.