As climate change increases the threat of wildfires in wine regions around the world, smoke taint has moved its way up the ladder of major concerns. Vintners in Australia's Hunter Valley believe much of their 2020 harvest has been lost to smoke taint. In California, Sonoma's Vintage Wine Estates (VWE) and Kunde Family have sued their insurance companies for refusing to cover wines damaged by smoke from the 2017 wildfires there.
But what if there were a way to protect grapes from smoke while the fires are raging? Researchers at Canada's University of British Columbia in Kelowna, where fires have been problematic in recent years, believe they have a potential solution in a product used in cherry farming.
The team had been working with Okanagan winemakers to find ways to detect potential smoke taint in wine grapes before fermentation so that winemakers don't continue pouring money and labor into a crop that is likely doomed. Current tests for smoke taint precursors are unreliable. Grapes can seem fine, but smoke taint emerges months later in the finished wine.
As Wes Zandberg, assistant professor of chemistry at the University of British Columbia, tells it, he and his team were working on problems related to quickly and accurately determining smoke-taint potential prior to harvest when it occurred to him that, "It would be better if we could protect the grapes from smoke damage in the first place," he told Wine Spectator.
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To begin work on the idea, in 2018 Zandberg and his students chose three common agricultural sprays: two approved for organic grape production in Kelowna to control powdery mildew and one used to prevent cracking in cherries as they grow when they're hit by rain.
The team placed a greenhouse over some vines, then pumped artificial smoke produced from local fuels inside a commercial food smoker into the greenhouse, exposing both sprayed and unsprayed grapes to smoke for two hours.
"One of the products didn't do anything, one appeared to intensify the smoke taint and one product [a phospholipid spray used on cherries] reduced levels of compounds responsible for smoke taint by 300 percent," said Zandberg. "We think it's kind of like putting a Teflon coat on the grapes."
They tested the protective sprays two years in a row, demonstrating that they could effectively block compounds from entering grapes. Since the spray is already approved for use on other agricultural products, including cherries and blueberries, they foresee few regulatory roadblocks, even if this is an off-label use. Zandberg said the most reasonable approach would be to make sure vintners have ready access to the spray and know how, when and where to apply it within the existing vineyard infrastructure.
As for practical application in an actual fire situation, Zandberg said, "I would think that quick action at the first sign of fire would be the best idea. One thing we're trying to deduce is how long any protection would last. There is some evidence that suggests the spray will provide a week's protection."
"This biofilm shows some real promise," said Dr. Anita Oberholster, cooperative extension specialist in enology at the University of California at Davis, whose research focuses on wildfire smoke's impact on grapes, "but further tests are needed to determine the best way to apply, the dosage, economics, duration of protection as well as any potential impact of this spray on winemaking and wine character."
The phospholipid spray, called Parka, forms a waxy cuticle on the grape skin. It's food safe and Zandberg said there was no difference in the rate of vinification between treated and untreated grapes. Tests would need to determine if the resulting wines were different, however.
Oberholster and researchers from three different universities are currently seeking federal funding for multiyear research on the effect of smoke exposure on wine grapes.
