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The Specter of Smoke Tainted Wine

In these long days of drought and climate change, wildfires are a constant concern in California’s Central Coast region. The so-called “fire season” now takes up most of the calendar.

In the past two months, as vineyards went through veraison (when grape ripening begins) and the harvest began, massive wildfires burned alongside the region’s top appellations. From August into early September, the west side of Paso Robles dealt with the 46,000-acre Chimney Fire, while the Santa Ynez Valley’s skies were clouded by the 33,000-acre Rey Fire.

Those were relatively minor concerns compared to what continues up the coast in Monterey County, where the Santa Lucia Highlands, Arroyo Seco and Carmel Valley have been contending with the Soberanes Fire for most of the summer. It’s charred more than 123,000 acres between Big Sur and the Salinas Valley since July 22, and isn’t expected to be fully out until the end of the month.

For the most part, these fires pose no lasting harm to vineyards or wineries. But they can cause winemakers to be concerned for a particular vintage’s wines. Wildfires that burn too close for too long are able to cause what’s known as “smoke taint.”

The problem arose most prominently during a wicked 2008 wildfire season in Northern California, causing many wines, most notably those from Mendocino County, to carry a particularly smoky aroma and flavor.

Since then, scientific studies in the U.S. and Australia have helped winemakers understand smoke taint. It’s led to a range of analyses to test for smoke taint as well as some remedies.

“First and foremost, nobody proposes that there are any health hazards,” says Gordon Burns. He founded ETS Laboratories with his wife, Marjorie, in their St. Helena basement in 1977 and grew the company into the industry leader for independent analysis of grapes and wine, testing for everything from brix to bacteria, phenolics to phthalates. The company now has five labs from Paso Robles to Walla Walla, Washington, more than 70 employees and the highest accreditation issued by the International Laboratory Accreditation Cooperation.

“It’s best not to overplay it,” he says. “Pretty much every year, there’s been a fire issue somewhere, so it’s bound to happen.”

While it remains unclear whether symptoms develop systemically through the vines or topically through the grapes, Burns’ team, led by research scientist Eric Hervé, has determined smoke taint settles in the waxy cuticles toward the outer skin of the berry, not in the juice or the flesh.

That’s why smoke taint levels can rise post-harvest, as the skins become integrated into the wine during fermentation. Because of that, it’s much more of a problem for red wines (whites are typically pressed off the skins quickly). It also appears to be most impactful toward the end of the growing season, after the grapes have gone through veraison.

ETS Laboratories
EST Laboratories / Photo via Facebook

From what Burns has seen, it also takes long-term, intense exposure to cause smoke taint to rise to levels “likely to have a sensory impact,” the measure that ETS Labs tests. The lab currently offers three smoke-taint panels that range from $135 to $180. Numerous Central Coast winemakers are using these services this year.

On the west side of Paso Robles, Justin, Halter Ranch and Daou all tested their grapes and found no impact. In Happy Canyon of Santa Barbara, in the eastern Santa Ynez Valley, Star Lane Vineyards’ winemaker Tyler Thomas knows about smoke taint. He witnessed it first-hand in Mendocino. Thomas also tested his grapes, and he was happy to find them clean.

The Santa Lucia Highlands and Arroyo Seco appellations also report clean bills of health, according to Kim Stemler, head of the Monterey County Vintners and Growers Association.

“Fortunately, the same natural factors that make Monterey the coolest growing region in California have also been protecting over 99% of the crop from prolonged exposure to smoke,” says Stemler, citing the coastal effects caused by the Monterey Bay.

There are four estates in the Carmel Valley, however, that may not be so lucky, says Stemler.

“This AVA is late to harvest, often not until the end of October, so it is not a foregone conclusion yet,” she says of the taint. “Most of these wineries also buy grapes from other vineyards, so if smoke taint is present within their estate grapes, it would only impact their estate wines, not the entire vintage portfolio.”

Stemler says that there are technologies for removing smoke taint as well. They include reverse osmosis as well as something called “flash détente,” a fast-extraction process where the berries are essentially exploded through heat and pressure. On the other hand, Burns warns that rinsing the grapes at harvest or basic filtration and fining are not likely to fix the problem.

“There aren’t very many good low-tech solutions,” he says.

Of course, smoke taint isn’t necessarily a bad thing.

“There are people who have had exposure and not thought of it as a negative,” said Burns. That’s because winemakers already use oak barrel aging to impart similar flavors. In fact, one of the tests that ETS Labs uses for assessing barrel impact looks for the same compound as its smoke taint panels.

Savvy winemakers could perhaps even save money in a smoky year by not buying new barrels, though no one is offering to be that test case.

In the meantime, as the drought persists, vineyard plantings continue to grow and wildfires become an increasingly normal part of California life. And thus, the specter of smoke taint will likely arise in every vintage somewhere in the state.

“This is not really a game-changing thing for the industry,” says Burns. “It’s yet another one of the challenges that winemakers could possibly face in dealing with Mother Nature.”