How Will The Westcoast Forest Fires Affect The 2020 Vintage

Ninety percent of the wine produced in the United States comes from the three Pacific Coast states of California, Oregon and Washington. During the month of September, a freak weather condition, described as a once in a generation phenomenon, overwhelmed the West Coast creating or fanning over 100 major forest fires and burning more than five million acres . The result was orange hued, smoke filled skies that seemed tailor made for a Martian dystopia. The full impact of this smoke on the region’s multi-billion-dollar wine industry is not yet known.

Initially, many wine producers expressed confidence that the impact of any smoke on the grapes could be managed. In Oregon’s Willamette Valley, the heart of Oregon’s wine production and its signature varietal Pinot Noir, many winemakers were confident that they could preserve what they had anticipated to be an epic 2020 vintage. Others were more guarded, but preferred to speak only off the record.

Over the last several weeks, as wineries began assessing the impact of the smoke damage, concern has steadily mounted that the West Coast wine industry could be looking at devastating losses. I underscore, could be, because no one really knows for sure yet. There are thousands of wineries on the West Coast. Not all were affected in the same way.

The impact of extended smoke exposure varies by varietal, the wine style produced and several other factors. To better understand the impact of the West Coast forest fires on the 2020 vintage I recently spoke with Dr. Elizabeth Tomasino, Associate Professor of Oenology in the Department of Food Science and Technology at Oregon State University. Dr. Tomasino and her colleagues have been working with the Oregon wine industry to determine the impact of the smoke damage and design protocols for measuring and mitigating the damage.

According to Dr. Tomasino, the principal culprits in “smoke effects” are volatile phenolic compounds: “whenever lignin, a major component of wood, is burned, it produces a range of phenolic compounds as byproducts of combustion.” Under the right conditions, those phenolic compounds are absorbed by the grape plant, including the maturing grape clusters. That’s where the potential problem begins.

The phenolic compounds combine with sugars in the grape clusters to form a phenol-glycoside: a compound formed from a simple sugar and another compound by replacement of a hydroxyl group (OH) in the sugar molecule. Per Tomasino these phenolic compounds are considered “bound.” They cannot be tasted or smelled by humans. All the phenolics absorbed by the grape plant are, initially, chemically bound to a sugar molecule.

Washing the grapes when they arrive at the winery won’t remove any of the bound compounds in the grape berries. Unfortunately, research on smoke effects have yet to uncover successful vineyard management practices for dealing with smoke in the vineyard. Future research will focus on developing procedures that would help stop the smoke. Currently, keeping the smoke out of the vineyard with fans is about the only option available.

The problem for winemakers is that the phenolics don’t stay bound to the grape sugars. They will break down, i.e., become disassociated. The yeast used for fermentation breaks down some of the glycosides releasing “free” phenolic compounds in the wine. The acids in the wine will also break down the bound phenolics, as will the passage of time. Enzymes in your saliva will do the same thing.

If the smoke compounds are at high enough levels, the unbound volatile phenolics created by the breakdown of the glycosides will give a wine a smoky, ashy, charred wood character that will make it undrinkable. Currently, it’s impossible to predict how fast those glycosides break down according to Tomasino. It’s entirely possible that grapes with high levels of glycosides can be vinified and the wines enjoyed before the glycosides break down.

Not all smoke is the same. The volatile phenolics produced by burning wood begin to dissipate from the smoke relatively quickly. The rate depends on the type of phenols, which in turn is a function of the species of wood being burned and the temperature at which it combusted. According to Tomasino, that creates a distinction between “new smoke” and “old smoke.” New smoke is created by a fire in proximity to a vineyard and will have higher levels of phenolic compounds then “old smoke” that has been around longer from a fire further away.

Whisky reviewers commenting on peated whiskies will often draw a distinction between smoke that is accompanied by phenolic/medicinal aromas and what is often described as cold smoke. Think of the smell of a previous night’s campfire on the following morning. New smoke is more likely to carry those phenolic aromas while old smoke is more likely to have that cold smoke character.

Some wine producers, for example, are already claiming that they won’t be affected by the smoke effects because their vineyards got old smoke rather than new smoke

According to Tomasino, there are several reasons why it’s not possible to have a firm cutoff above which the level of bound phenolics will make wine grapes un-useable. Likewise, Tomasino, is also reluctant to set a lower limit below which smoke effects are not discernible. She points out that in addition to the variations in human sensitivity it will also depend on how the grapes are vinified.

Human sensitivity to phenolics varies widely. About 20% of the population is completely insensitive to phenolic compounds. Others may be more sensitive. All wines naturally have some volatile phenolic compounds, typically byproducts of fermentation. As a rule, however, concentrations found in wine are usually too weak to be perceived by wine drinkers.

Moreover, “Every wine has a different combination of aroma compounds,” says Tomasino. Adding, “the more complex the wine the better it can incorporate those phenolic notes and the less evident they will be.” “We simply don’t know yet how vinification and maturation protocols will affect wine made from smoke effected grapes,” she states.

Several wine makers have pointed out to me that concentrations of volatile phenolic compounds as low as three parts per billion (PPB) could be discernible in wine. This is an almost unimaginably small number. Here’s one way to visualize it, it’s the equivalent of nine seconds in a century.

Having written about whiskies, and especially peated whisky, for 20 odd years, I found those concentrations to be incredibly low. In the case of whisky, for example, the perception level of phenolic compounds from the peat smoke in a whisky is typically around three parts per million (PPM). That’s over a thousand times higher than in wine.

It’s the alcohol, says Tomasino, which explains the difference, noting that higher levels of alcohol will mask the smoke effect. “If you had a wine that was 40% alcohol,” she points out “it would cover up a lot of smoke compounds but then it wouldn’t be a wine anymore.” According to Tomasino, “more complex, higher alcohol wines may mask the smoke phenolics better than lighter styled wines.”

Tomasino’s observation is consistent with comments from several Willamette Valley wine producers who have argued that 2020 is the year to produce big concentrated wines from over ripe fruit with high alcohol levels to help mask the smoke effects.

That’s not necessarily going to be easy, however. There have already been periods of heavy rain in the Willamette Valley over the last week. As one prominent producer put it, rain and letting fruit overripen don’t go well together. The weather is supposed to be warm all next week, but that same producer pointed out that warm, dry weather after heavy rains can often set the stage for an explosion of disease pressure in the vineyard.

By the time the smoke hit Oregon vineyards, most of the Chardonnay had already been picked and was in process of being vinified. Several growers have pointed out that “what wasn’t picked seemed to handle the smoke without any lasting damage.” “It was a great crop this year,” remarked another grower adding, “most producers were unaffected by the smoke.”

Late ripening varieties like Riesling and Pinot gris are, according to several producers, probably a complete write off. It’s the Pinot harvest that is potentially the most affected and the most important since Pinot noir accounts for roughly two-thirds of Oregon’s wine production.

Several wine producers have suggested that smoke affected Pinot noir grapes could be used to make rosé or white pinot instead of the usual dry red wine. This won’t solve the issue, however. As pointed out earlier the phenolic compounds are not on the skin they are bound up with the sugars in the grapes, minimizing skin contact won’t make a difference.

One intriguing possibility is using grapes that have low levels of smoke effects to make sparkling wines. Wines that undergo a long period of maturation on the lees can often develop a pronounced smoky note. In sparkling wines this is not considered a fault, although it’s not to everyone’s taste. Oregon’s sparkling wine production is probably not much more than 50,000 cases a year, however, a fraction of the amount of dry red Pinot Noir wine produced.

It’s important to note, Tomasino points out, that this is a very fluid situation. Many questions remain to be answered. The fact that few if any solutions for dealing with smoke effects have emerged so far, doesn’t mean that they won’t. The West Coast has many experienced and capable winemakers, some even brilliant.

Moreover, it is difficult to generalize across thousands of wineries and vineyards spread over three states. Some vineyards will experience little if any lasting damage from the forest fires, others won’t be as lucky.

Vineyard owners who sell their grapes to wine producers are in a particularly tough spot. Some wine producers have already announced they will not be taking any grapes in from third party growers because of concerns about smoke effects.

Others are offering 25% of their normal payment to simply leave the grapes unpicked. Even if solutions for managing the smoke effects are eventually discovered, they may come to late to help most independent vineyards.

Stay tuned. We’ll have a better idea of the consequences of the West Coast forest fires and their impact on the 2020 vintage over the next few weeks.

By Joseph V Micallef, Contributor