Finally, Some Good News About Smoke Taint

Smoke taint is a scourge that can ruin a harvest. But as Jeff Siegel discovers, research has unlocked some answers.

Reading time: 5m

(Photo:  Kondor83/, generated with AI)
(Photo: Kondor83/, generated with AI)

Using the adjective ‘giddy’ to describe a researcher’s mood isn’t common. Researchers, after all, often take years to make progress, meaning that patience is a more typical mindset.

But Oregon State researcher Elizabeth Tomasino, PhD, is practically giddy about the progress made in understanding and combating smoke taint over the past five years.

“Yes, we’ve made a lot of strides,” says Tomasino, an associate professor who also works with the school’s Oregon Wine Research Institute. “And the progress we have made has been quite exciting.”

So exciting, in fact, that researchers around the world may have, since the first California wine country fires, identified new tools for grape growers and winemakers to use to predict if and how badly taint could affect their grapes. And even, perhaps, ways to better diminish the effects of smoke taint.

Having said that, there is still a long way to go.

“We get questions all of the time, and it’s perfectly understandable, like ‘Why can’t we just wash off the grapes?’ “ says Tomasino. “But it’s not that simple, even if we wish it would be.”

The impact of smoke taint

There’s a simple reason so little is known about smoke taint and what it does to grapes and wine. It hasn’t been a problem, save in Australia, for most of the past century (if not longer). Tomasino says there has been almost no research done in the previous century, given how few instances of smoke taint were seen and how few fires affected vineyards before climate change increased wildfire chances in the past 20 years. “You don’t need to know about something like wildfires until they happen,” she says.

The exception was one European study some 80 years ago, but that hasn’t been much help, she says. Those early 20th-century researchers, while identifying some of the symptoms and results of smoke taint, weren’t quite sure what they had found.

That all changed in 2017 in California, when smoke taint became a problem that couldn’t be ignored. It was the beginning of coordinated research in North America in California, Oregon, Washington state, and Canada’s province of British Columbia, as well as continued efforts in Australia, where the latter have made tremendous strides in identifying taint and its effects.

“Smoke is a highly complex mixture consisting of solid and liquid aerosols, gases and hundreds of volatile and semi-volatile organic compounds,” says Mango Parker, a senior research scientist at The Australian Wine Research Institute near Adelaide, where some of the most cutting-edge work is being done. Typically, she says, these are taken up by grape berries and leaves and they can persist in the wine, and contribute smoky aromas and flavours to the wine.

“Interestingly,” she explains, “they can break apart in the mouth, releasing smoky flavour that can linger for minutes. And washing grapes doesn’t solve the problem as the compounds are taken up into the tissue.”

What has been done since then, say researchers, is to amass data to understand even more about taint and to help growers and producers focus on prediction — will a fire send smoke and then taint into their vineyards? — as well as vineyard treatments to prevent the effects, plus more understanding of the taint process.

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Where the research into smoke taint is up to

That research has fallen into three categories. First, predictive modeling. Compare it to a weather forecast — if there’s a fire nearby, what are the chances that it could taint the grapes? Currently, little is known about this, but researchers at the University of California Davis are focusing on creating models that answer those questions. Significant progress has been made, but researchers say more time will be needed, and that just three or four years of data isn’t enough.

Second, protective coatings for grapes that could limit taint’s damage, the equivalent of a vaccination. Progress has been made here and, hopefully, more progress can be made over the next several years.

Third, more specifics about the taint process, which would help with finding a vineyard preventive as well as winemaking techniques to fix tainted grapes. The Australians, says Parker,  have done extensive work to see if smoke taint carries over from vintage to vintage; it doesn’t seem to.

“I’m only aware of one study which showed an impact on a subsequent year,” says Parker. “That was an early study where smoke was deliberately applied to vines via a smoking tent. It showed no smoke-related grape or wine composition effects in the following year, although the next year’s yield was reduced.”

The not-so-good news from a 2020 study is that smoke can harm grape and wine quality even when the grapes are small, hard and green, well before veraison.

“This was in contrast to what we believed from earlier model smoke experiments that showed lower risk of smoke taint earlier in the season,” says Parker. “Since this finding, we now advise that smoke poses a risk to grapes throughout the whole period when grape berries are on the vine. We haven’t seen any evidence of smoke impact during flowering or prior to flowering.”

What’s known about smoke taint chemistry

Changes in flavor and aroma have been attributed to high levels of compounds called volatile phenols. But they weren’t always a good predictor of taint. Could there be other compounds involved?

A group led by Tomasino uncovered one such compound, called thiophenols, which doesn’t occur naturally in grapes. But it does seem to be present in smoke-tainted grapes, offering what Tomasino calls a “new chemical marker for smoke taint that could provide a reliable way to identify smoke taint and ways to potentially eliminate it during the winemaking process.” The next question to be answered: If winemakers can efficiently remove the thiophenols, they can eliminate smoke taint?

Tomasino says the key is gathering quality data and having the money to do so. She credits grants and research assistance in the US. from the Federal Department of Agriculture. This has allowed a variety of efforts from across California and the Pacific Northwest to work in tandem across the whole of smoke taint, instead of attacking it piecemeal, from one area at a time.

Insurance ...and damages

Grape growers in 32 California counties will also be able to add fire insurance protection for smoke damage to their grape insurance policies, starting in 2025. The pilot program, with premiums subsidised by the federal government, will allow growers to make claims based on “eligible smoke days” in their region.

Plus, two West Coast utilities have recently agreed to pay damages for their roles in starting several of the most deadly wildfires. Oregon’s Pacific Power announced at the beginning of June that it would make a $178 million settlement with more than 400 Oregon plaintiffs in the latest multimillion-dollar payout related to the 2020 wildfires. The blazes were among the worst in Oregon history, killing nine people, burning more than 1,875 square miles (4,856 square km) and destroying thousands of homes.

Meanwhile, Pacific Gas and Electric said earlier this year it will pay $45 million in penalties for its role in the 2021 Dixie Fire, the second-largest in California’s history, that started after a tree fell and hit the company’s equipment. This is the latest in numerous settlements the bankrupt utility has made with California regulators and plaintiffs over the past several years for its part in a host of fires, including the 2019 Kincade Fire in Sonoma County.

The next question is whether more progress can alleviate the need for compensation after the next round of fires.


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