UBC Theses and Dissertations
Smoke-taint : chemically characterizing smoke-exposed Vitis vinifera L. berries and wines to inform the development of preventative and remedial strategies Noestheden, Matthew
The on-vine exposure of Vitis vinifera L. berries to the smoke from wildland fires can make wine made from those berries taste unpleasantly smoky and ashy. In the wine industry, this defect is known as smoke-taint and it has been linked with increased concentrations of organoleptic volatile phenols (i.e., guaiacol, cresols, etc.) and their glycosidically-bound derivatives in smoke-exposed berries and the resulting wines. The financial impact of smoke-exposure to the wine industry can be significant (e.g., $300 million in lost revenues from fires in Australia in 2009) and climate change models suggest that wildland fires will increase in severity and frequency in regions growing Vitis vinifera L. around the world. This makes smoke-taint a present and future concern for the sustainability of the global wine industry. To try and improve the accuracy of predicting a smoke-tainted wine based on the chemical composition of the berries and to support efforts to mitigate the impact of smoke-exposure, this work investigated: 1) the accuracy of existing methods to quantitate volatile phenols and their glycosides; 2) the metabolic flux of volatiles phenols and their glycosides in berries following smoke-exposure; 3) methods for the detailed characterization of glycosidically-bound volatile phenols; and 4) changes to non-volatile phenolic metabolites. Addressing these research areas was facilitated by systematically developing a suite of mass spectrometry-based analytical methods. These methods were used to characterize field trials over two seasons, with the results demonstrating the complexity of the chemical changes associated with smoke-taint. This included a rapid increase in total volatile phenols (i.e., free and chemically-bound) in berries following smoke-exposure, indicating that analytical assessments of berry quality may be conducted much earlier in the growing season than previously appreciated. Putative regional differences in the chemical expression of smoke-taint, including volatile phenols, their glycosides and phenylpropanoid metabolites, likely preclude the development of a globally-applicable predictive algorithm for smoke-taint in wine based on the chemical composition of the berries. These data provide context for future research that will help the wine industry develop appropriate risk-management strategies, including potential solutions to mitigate the impact of berry smoke-exposure on wine quality.
Item Citations and Data
Attribution-NonCommercial-NoDerivatives 4.0 International