Discovery could prevent grapes tainted by wildfire smoke from ruining wine

Wildfire smoke and vineyards do not mix well if you want a pleasant bottle of wine, and now researchers in the Northwest have found a new way to alert winemakers if their grapes have been tainted before they're used in creating a prized batch of vino.

FOX Weather reports wildfires have been increasingly prevalent during West Coast summers, with recent ones marred by weeks or even months of thick wildfire smoke blanketing stretches of California, Oregon and Washington – three of the top four wine-producing states in the U.S., according to Wines Vines Analytics.

Smoke from the Glass Fire hangs heavy over a vineyard outside of Calistoga in Napa Valley, California on September 30, 2020. (SAMUEL CORUM/AFP / Getty Images)

Using grapes that have been exposed to wildfire smoke can affect both the taste and smell of wine, affecting the desired product, according to researchers. In the past, winemakers used measurements of compounds known as volatile phenols to estimate how much a grape may have been affected by smoke.

Smoke rises into the sky behind Sterling Vineyards along Silverado Trail during the Glass Fire in Napa County, California, U.S., on Sunday, Sept. 28, 2020. (Philip Pacheco/Bloomberg / Getty Images)

Researchers found the measurements were an unreliable indicator, with some grapes showing high levels of the compound coming out with a clean taste, according to Elizabeth Tomasino, an associate professor of enology at Oregon State University who helped lead the study. Yet some batches of grapes with low levels were found to taste smoky.

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That prompted a search for a better indicator of smoke impacts, and last year Tomasino's team discovered smoke-tainted grapes also contained a class of sulfur-containing compounds known as thiophenols.

Thiophenols are not naturally found in wine but are found in meat and fish, which gives both a meaty and burnt flavor.

Weeding out sour grapes

To test their theory, researchers enclosed a row of grapes inside a greenhouse filled with smoke, while leaving other grapes in clean air. The results confirmed the presence of thiophenols on the smoky grapes, but not on the unexposed grapes.  

Pinot noir grapes at Oregon State University's Woodhall Vineyard undergoing smoke experiments. (Sean Nealon, Oregon State University / FOX Weather)

The discovery brings hope that winemakers can better weed out smoky grapes that could ruin a batch during the winemaking process.

"These findings provide new avenues for research to understand and prevent smoke taint in grapes," Tomasino said in a press release announcing their study's findings. "They also will help provide tools for the grape and wine industries to quickly make decisions about whether to harvest grapes or make wine following a smoke event."

Meaning their wines could taste as the vintners intended instead of a reminder of the smoky summers during that that growing season.

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The study by researchers at Oregon State University and Washington State University was recently published in the journal Food Chemistry Advances.