RICHLAND, Wash. – As wildfire season scorches the Pacific Northwest, Washington State University researchers are working to find new ways to mitigate wine grape smoke exposure.
Projects include installing air quality sensors at vineyards, laboratory experiments where grapes are exposed to smoke, and potential interventions such as using a barrier spray to protect the grapes.
“A big part of our latest research proposal is collecting atmospheric data to build a model for predicting where smoke risk is highest,” said Tom Collins, assistant professor for the WSU Wine Science Center.
Air quality sensors are being installed in commercial vineyards throughout central Washington to collect smoke density information as wildfire season continues. The WSU researchers plan on using the atmospheric movement and airflow data they collect to better predict where to expect wildfire smoke and where it might go next.
“We’re trying to figure out how much smoke it takes for wine grapes to be at risk,” said Layton Ashmore, a WSU doctoral candidate in food science.
Part of the research efforts involve exposing grapes to simulated smoke. The grapes are exposed to smoke for 36 hours with samples taken every six hours to analyze how different amounts of smoke might affect the grapes and ultimately, the final wine flavors. Collins is still processing outcomes from last year due to COVID-19 protocols slowing down the ability to analyze data at WSU’s Wine Science Center.
One method Collins is trying again this year is a barrier spray, where water mixed with Kaolin clay is sprayed on the grapes to limit fruit uptake of the smoke’s volatile chemicals. So far, the results have been mixed.
“What we’re looking for is fruit with a lower concentration of smoke compounds,” he said.
One of the challenges with barrier sprays is that compounds from the spray might still be on the fruit and therefore in the wine. This year, Collins and his team plan to spray the fruit and remove the coating on the grapes before harvest.
Researchers are also trying to determine if wildfire smoke from different types of plants might alter the taste of the wine.
“Done earlier in the season, these measures could allow growers and winemakers to make plans if they feel their vintage might be affected,” Collins said.
Meanwhile, Ashmore advises growers to be cautious about marketing gimmicks and products claiming to solve the problem of smoke exposure.
“We want winemakers to have all the tools that science can give them, so they can make an informed decision about what they want to do,” he said.
The Washington state wine industry has funded WSU research into smoke exposure since 2016, according to Melissa Hansen, research program director for the Washington State Wine Commission.
“It is one of the most complicated issues to face the wine industry in a long while,” she said. “The impact of smoke on grapes depends on many factors from length of time exposed, which variety, proximity to fire, type of material burning, freshness of the smoke, weather patterns and more.”
While the wine industry has learned a lot about how smoke affects grapes and wine, there’s still much more to understand, Hansen said.
“In recent years, there’s been great collaboration between WSU, Oregon State University, University of California and USDA’s Agriculture Research Service,” she said. “The research team is making good progress; we just can’t make the research happen fast enough.”
Collins said one of the precautionary measures growers can implement in the event of smoke exposure is to collect and freeze grape samples, or do small scale fermentations to test if the harvested fruit creates a smoky wine flavor.
Results from Collins’ experiments will be ongoing, with data from the early season trials expected in late summer 2021. This research is funded by Washington State University, the Washington State Department of Agriculture (WSDA), the United States Department of Agriculture (USDA), the Agriculture Research Service (ARS), Auction of Washington Wines, and all of Washington’s wine grape growers and wineries in partnership with the Washington State Wine Commission.