Newswise — The October fires in Sonoma, Napa and Mendocino Counties scorched more than 180,000 acres in Northern California, destroying thousands of homes and resulting in the deaths of 40 residents. The fires also damaged or destroyed at least 27 wineries in that North Coast wine region, according to news reports.  In the wake of the fires, experts in the wine industry are assessing the near-term impact of the blazes on California wines, which are renowned across the globe. 

Overall, winemakers in the area were largely spared by the fires, says Honore Comfort, Executive in Residence at the Wine Business Institute at Sonoma State University.

"Only a small number of the more than 1,000 wineries in Sonoma and Napa were affected by the fires to the point of limiting production or damaging inventory." 

When Smoke Gets in the Vines

Still, as wineries have begun the winemaking process for the 2017 vintage, there is concern that smoke from the fires could have tainted some grapes.

The chance of "smoke taint" forces wineries to decide whether or not to use the grapes for wine, discard the grapes, or treat the fruit during winemaking to remove the smoky aroma.

Ninety percent of the season's grapes had already been picked before the fires, so the impact is expected to be minimal. Nonetheless, winemakers will need to evaluate every lot of grapes they have to see which may have been affected, says Comfort. 

Any fruit still on the vine when the fires spread or close to the smoke could be affected, adds Miguel Pedroza, Ph.D., Assistant Professor of Enology at California State University, Fresno, home to Fresno State Winery.

"It depends on how much of the smoke was in contact with those grapes," Dr. Pedroza explains. "When smoke is present, it can impregnate the grapes through the leaves of the plant. The leaves will actually capture that smoke and eventually transport it to the grapes and accumulate that smoky smell inside the grapes." 

Smoke can also attach to the surface of the grapes, which then gets transferred to the juice that will eventually be fermented and turned into wine. "When the smoke coats the outside of the fruit, it's hard to get rid of it," cautions Tom Montgomery, winemaker and instructor at Fresno State Winery, who spent 16 years working at Napa and Sonoma wineries, producing award-winning wine.

But smoke taint may not be a total deal breaker. During the winemaking process, reverse osmosis can be used to remove the smoky aroma, which "doesn't taste pleasant, like the toasty oak flavors we enjoy in pinot noirs, cabernet. It tastes more like the smell of the dank ashtray your grandmother had," says Montgomery.

Some Northern California wineries are having their grapes tested at labs to assess if smoke taint is present, and will then decide how to treat it during the winemaking process using methods such as reverse osmosis to proceed with winemaking.

Fewer Bottles, Premium Prices?

This year's grape season was comparatively short, with lower yields of certain varieties of grapes. This, along with the grapes that have smoke taint, could contribute to a decrease in the supply of some California wines.

In particular, these factors "could affect the supply of cabernet sauvignon, so the price could go up for high-end cabernet," says Montgomery. "But nobody has seen hard numbers. Everybody is speculating, including me."

Comfort notes that each winery determines its own pricing, and grape quantity is just one of many factors that influences how much a wine costs. Packaging, distribution, shipping and transportation, and competition all drive pricing as well. 

"Napa, Sonoma, and Mendocino Counties together represent about 12 percent of California's total wine grape production," she explains, noting that a very small percentage of the 2017 harvest was directly affected by the fires. "There is no sign or expectation of a shortage and related price adjustments across the North Coast region at this time."

Other signs point to a bright picture for wine: Ninety percent of grapes were harvested in the region prior to the fires; grape yields were at or just below average for the leading varieties; and the grapes have excellent fruit character, according to Comfort.

Sauvignon blanc, pinot noir and chardonnay grapes were already in barrels at wineries waiting to be bottled at the time of the fires.

Montgomery is optimistic as well about the wines consumers can expect to drink in a couple of years: "The effect of the recent fires was limited. Most of the [new] wines the customers see will be smoke taint-free. 

"Overall, the vintage was good, so in general, we have some very good wines to look forward to."