Impact of copper ion concentrations on flavor quality from grapes to wine.

Prolonged application of copper-based fungicides in the vineyard can lead to increased copper levels in the grapes and wines, affecting flavor quality. In this study, we systematically investigated the effects of copper treatment on grape and wine flavor by simulating copper-based fungicide application in vineyards. The results indicated that medium-to-high copper treatment limited berry maturity to significantly reduced the sugar-acid ratio of berries and inhibited the synthesis of total phenols and most individual phenolics and reduced antioxidant activity. And copper treatment significantly regulated the volatile compounds in the berries, with low copper treatment accelerating berry maturity and decreasing the content of C6 compounds and aldehydes, while medium and high copper treatment significantly increased their content. In addition, terpenes and C13-norisoprenoids in grape berries were the key aroma compounds that decreased with increasing concentrations of copper treatment. Thus, more careful application of copper-based fungicides will be needed in the future.