CHARLES Sturt University has started a second research project into sunburn on grapes as winemakers continue to struggle against hot conditions.
PhD student Julia Gouot is operating from the National Wine and Grape Industry Centre to study the impact of heat waves on the physiology and composition of shiraz grapes during their development and ripening, focusing particularly on tannins.
“So far, my research has examined the impact of three-day heat waves at the bunch and whole-vine levels,” Ms Gouot said.
“We’re interested in seeing how that influences compounds such as phenolics in berry skin and seeds, and sugars and acids in the pulp.”
She will also assess how the compounds can be extracted during the winemaking process.
“Phenolics can contribute to wine colour and taste or mouthfeel, so it is essential to understand how they are affected.”
The other set of sunburn research is being conducted by CSU’s Dr Joanna Gambetta, focusing on how pruning techniques could help protect grapes from damage.
See Saw Wines owner Justin Jarrett previously commented sunburn caused shiraz to taste like fruitcake.
Ross Hill Wines owner Peter Robson said his vineyard’s shiraz was not at risk of sunburn yet.
“But the world’s changing so rapidly, you never know,” he said.
“Orange in the last few years is getting hotter, we didn’t have the problem 10 years ago we do now and our picking season has come forward three weeks.”
Mr Robson said his vineyard experienced the problem with chardonnay and pinot noir.
“Ours is a highly crisp chardonnay so the primary source for that is getting good protection from the sun so when the grapes get to the winery, they’re still green,” he said.
Research supervisor and chemistry senior lecturer Dr Celia Barril said climate change was likely to result in earlier, more frequent and intense heat events.
“This will impact on berry development and maturation, and composition by harvest,” she said.
“It’s hoped the research will give growers and winemakers more information about the impact of heat waves on berry survival and quality to guide decision making.”
The NWGIC is an alliance between CSU, the DPI and the NSW Wine Industry Association.
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