Where There’s Smoke, There’s Tainted Grapes: How Researchers Are Trying to Remedy Smoke Taint

BY KATE DINGWALL .THE WINE ENHUSIAST

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Chris Fladwood, head winemaker at Soter in Oregon’s Willamette Valley, expected 2020 to be one of the most incredible years the state had ever seen. It was dry, warm and consistent, with cool nights that ushered grapes to ideal ripeness.

But a pandemic hit. Then fires—larger than those that struck in the last 36 years combined—spread through the valley. For many winemakers, all was lost.

This event was far from unique. Extreme firesravaged California in 2020. Australia suffered devastating blazes in 2019 and 2020. The Okanagan Valley burned in 2021 and 2023. Across the world, it’s resulted in lives lost and acres upon acres of land scorched. Winemakers have been forced to make tough decisions. When smoke hits a vineyard, volatile phenols bond with the skins of the grape and penetrate the fruit with persistent smoky flavors—sanguine and slightly charred in the best of cases, overtly ashtray in the worst. The resulting wine is often unsalvageable.

New Innovations

OSU researchers are testing a spray that provides a protective barrier from wildfire smoke—damage that resulted in more than $3 billion in losses in 2020 alone. Made from cellulose nanofiber, the spray can block many phenols (including guaiacol and syringol) and capture others, even after absorption. The product is expected to be available in the next several years, though there are a few hurdles to clear first, like finding a formulation that guards against all, not just some, of the more than a dozen flavor-impacting compounds in smoke.

This new technology offers hope, but U.C. Davis’s Anita Oberholster believes a “silver bullet” solution is far away. She points out that most smoke taint research is under five years old. “We only really started getting funding for this work after the 2020 wildfire,” she says.

In 2021, she applied 12 FDA-approved products on grapes to test their ability to reduce smoke damage. Only two had potential: kaolin, a clay-based productused to shade grapes from sunburns, and a powdery mildew spray.

Neither are fail-safe—they’re a pain to apply. If you spray the products through the vineyards, coverage is spotty. “So, are you going to hand-dip every single bunch?” she says. “Maybe in high-end vineyards, but the labor and the cost would be prohibitive for most vintners.”

Expense and logistical issues aside, the use of these complex polymer sprays raises other questions for the vinification process. “There are issues of if these coatings will affect the winemaking process,” says Adam Casto, head winemaker at Ehlers Estate in Napa Valley. “I’ve farmed both organically and biodynamically and I’m not really into putting things on the grapes I’m unfamiliar with.”

He thinks it will take years for this new technology to get traction. “To gain the cultural penetration that would be required for this to be a large-scale deployment would take half a generation,” he says. “Think about it: Anytime there’s a shift in fermentation tank styles, yeast approaches, sulfur management protocols or any other developments, it takes a good 10, 15 years to be broadly absorbed and accepted.”

Playing Guessing Games

Why is smoke such a complicated topic? It’s unpredictable—its path is dictated by nature and even in a vineyard, location, elevation, climate and grape varieties can affect how much smoke phenols are absorbed.

“Just because smoke hits and the fruit smells and tastes of smoke, it doesn’t mean that smoke has impacted your fruit in a devastating manner,” says Casto. Luck is a large factor, but varietal choice and winemaking style can also influence the effects of smoke.

Different varietals respond to volatile smoke phenols in their own ways. Since smoke permeates the skin of the grape, thicker-skinned grapes like Chardonnay and Syrah are less susceptible to damage, while Pinot Noir’s delicate skins do little to protect the fruit. Minimizing extraction or cold maceration (a.k.a. cold soaking) can reduce some smoke flavors, though these processes limit the style of wines you can produce. The addition of oak, either through chips or barrel-aging, can mask some of the more unpleasant effects of smoke taint.

“You can have two wines with the exact same smoke marker profile and they will seem different,” says Oberholster. A touch of smoke isn’t always bad, she adds. “These phenols are the same compounds that get released when you toast a barrel. At low levels, they’re actually a good thing—they’re pleasant, nutty, sweet, spicy and oaky. It’s at high levels that they become obnoxious.”

Oberholster is researching the difference in grape varieties and winemaking styles so she can set a standard for the upper limit of smoke infliction—in other words, when winemakers should call it. She’s also interested in predictive sensory modeling, which looks at the atmosphere, what plants and trees are burning, wind speed and movement and duration of exposure to understand the gravity of smoke damage.

“These technologies exist in other fields,” says Casto. “It’s just applying them to viticulture. There are challenges—how to get high-speed internet to remote areas, signal availability and electricity—but those are far more tangible challenges than predicting fire patterns.”

DIY Remedies

Because there are still no clear solutions, winemakers have been investigating potential fixes on their own.

Fladwood has only had one year of experience with a smoke-affected vintage. When multiple fires emerged from the Cascade Range and Chehalem Mountain in 2020, California winemakers he spoke to warned him to give up hope. “That doesn’t sound like a winemaker,” he says. “Whether it’s smoke, rain, heat, birds, mildew, botrytis or frost, every year is marked with hurdles. Some are harder than others, but they’re all challenges.”

He tried everything—spraying the vines with water to wash off the sulfur and ash. They pulled leaves off the west side of the canopy, which would usually cause sunburns, to let rain clean the grapes. Instead of picking early to avoid smoke, he let his grapes ripen as normal. With so much unpredictability, he at least wanted the correct tannins and fruits in his wine.

As he racked the wines from fermenter to tank, layers of ash appeared in the bottom of the tank. “It was completely alien,” says Fladwood. He cooled, resettled the wine and added yeast, which has a propensity to absorb odiferous compounds, repeatedly until the ash disappeared. “It was like whack-a-mole: smoke would pop up and we’d hit it with yeast.”

That harvest was debilitating, filled with evacuation and overtime. But for small wineries, he sees no other solution. “We’re not owned by a billionaire,” says Fladwood. “We can’t just throw things out.”