Impact of grapevine exposure to smoke on vine physiology and the composition and sensory properties of wine
Smoke was applied to seven different grapevine cultivars (Chardonnay, Sauvignon Blanc, Pinot Gris, Pinot Noir, Shiraz, Cabernet Sauvignon and Merlot) for 1 h at approximately 7 days post-veraison. A range of viticultural measurements were subsequently performed to evaluate any effects on crop yield, vegetative growth and vine physiology. Few significant differences in berry growth or maturation (as sugar accumulation), yield or vine growth were observed between control and smoke-affected grapevines; but the photosynthetic capacity of some varieties, Merlot and Cabernet Sauvignon in particular, decreased significantly following smoke exposure. The extent of smoke taint in the resultant wines was then determined by quantification of volatile phenols and guaiacol glycoconjugates, and by descriptive sensory analysis. Elevated concentrations of volatile phenols and guaiacol glycoconjugates were observed in wines made from smoke-affected grapes; with smoke-affected Pinot Gris and Cabernet Sauvignon wines found to exhibit the most intense smoke-related sensory attributes. The physiological, compositional and sensory consequences of grapevine exposure to smoke were found to vary amongst cultivars, suggesting some grape varieties might be more susceptible to the effects of smoke exposure than others. Further research into the impact of smoke exposure by different cultivars might inform varietal selection in smoke-prone wine regions, in order to mitigate the risk of smoke exposure.
KeywordsBushfires Cultivars Smoke taint Volatile phenols
This research was supported under the Australian Research Council’s Linkage Projects funding scheme (LP0989138); the financial contributions of industry partners are also gratefully acknowledged. Anthea Fudge and Kerry Pinchbeck thank Wine Australia for the provision of research scholarships. The authors would also like to acknowledge: the vineyard owners and managers who participated in the project; the sensory panel for their invaluable contribution to wine sensory evaluation; Andrew Markides of Lallemand, Australia for the provision of yeast and winemaking consumables; Margaux Vigy and Jesse Graffam for technical assistance; and the Australian Wine Research Institute’s Commercial Services Laboratory for GC–MS analysis.
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