By: Becky Garrison
In a press release dated May 5, 2023, Willamette Valley Vineyards, Brigadoon Wine Co., Samuel Robert Winery, Retraite, LLC (F/K/A Lingua Franca – LS Vineyards Holdings, LLC) and Elk Cove Vineyards Inc. announced they hired a well-known legal team to investigate filing suit against Pacific Power, a division of PacifiCorp, in the Oregon state circuit courts. The wineries issued this joint statement:
“These fires devastated our industry, and we believe it’s time we investigate seeking compensation. We are encouraged by the recent news reports that the other fire victims in the state are finally able to settle their claims against Pacific Power (PacifiCorp). We have hired the lawyers who led the $13.5 billion recovery for the 70,000 victims in the PG&E bankruptcy in California and who recently settled their lead fire victims’ claims against PacifiCorp in the Archie Creek Fire litigation in Douglas County, Oregon.”
As evidenced by the wildfires impacting the West Coast in subsequent years, coupled with the current wildfires raging in Canada impacting the East Coast and the Midwest, the issue of smoke damage to wine grapes remains an ongoing concern. During the Oregon Wine Symposium held on February 14-15, 2023, moderator Greg Urmini, operations lead for White Rose Estate in Dayton, Oregon, led a panel of winemakers and researchers to discuss smoke-impacted wine. Urmini pointed to the significance of this topic, noting, “It’s important to understand what winemakers are doing to help save their wine because we have to continue to make wines, and we want to be able to provide a good product.”
CASE STUDY: Barrel 42 & Quady North Winery (Jacksonville, Oregon)
As a founding member of the West Coast Smoke Exposure Taskforce, Nichole Schulte, winemaker and partner of Barrel 42 and Quady North Winery, has experienced trial by fire literally while dealing with multiple smoke indigents over the past decade in Oregon. Overall, she stresses the need to collaborate with local winegrowers and winemakers ahead of time so there’s a strategy already in place regarding what can be done in the winery and the vineyard.
In assessing the risk of a particular wildfire, Schulte looks at three factors. First, she observes the proximity of the smoke event to the vineyard, adding that the AQI (Air Quality Index) measurements do not provide a direct relationship between air quality and the volatile smoke-related compounds (“phenols”) floating around in the air. Also, she examines the freshness of the smoke, adding that these phenols can degrade or drop out over time.
The grapes soak up these phenols, which bind to sugar though how much sugar is absorbed by the grapes depends on the varietal and the growing stage. Some grapes ranked from highest to lowest risk for negative effects from smoke damage include pinot noir, grenache, sangiovese, cabernet franc, primitivo, zinfandel, cabernet sauvignon, merlot and syrah.
While the most vulnerable times for grapes coincide with wildfire season, there’s no carryover impact in the vineyards from previous wildfire events. Preliminary indications of using barrier sprays in the vineyard show to be very promising. In addition, hand harvest reduces maceration time from harvest to the fermenter. Sort out as much MOG as you can, which means not doing a full cluster ferment. Whole berry ferments tend to produce fruity aromas and esters that can, to some degree, mask the smoke characteristics in the wine. Along those lines, there’s some indication that washing ash off the fruit clusters can help reduce the presence of smoke.
As you handle smoke-impacted grapes from fermentation to élevage, be mindful that volatile phenols will express early in fermentation. When doing trials where they separated press factions, the data showed that the compounds were still present but that the sensory profiles differed from a light to a heavy press.
When conducting experiments to see how certain barrels interact with smoke-impacted wines, they found that the higher the toast of the barrel, the more it interacts positively with the smoke impact of the wine. Also, untoasted oak chips can mask and bind up some phenols, while toasted oak can provide sweet, more complex tannins.
In Schulte’s estimation, white wine is easier to deal with since you can get the juice off the skin as soon as possible. Hand-harvest the grapes and minimize skin contact and maceration time. Press gently, keeping heavy-pressed juice segregated for possible treatment later or just to keep it out of the main juice. Be sure to discard the solids, though this can be tricky as yeast will need some solids. So, consider using solids and lees from non-impacted lots. But if you can clarify before fermentation, then there’s almost no smoke at the end. For fining, they had success with bentonite, activated carbon and PVPP, as well as Clanil SMK (Enartis), which is a blend of activated carbon, chitosan and pea protein.
Finally, wine made from smoke-impacted grapes should be bottled and consumed early. Aging these wines will not improve their quality.
CASE STUDY: Battle Creek Cellars (Portland, Oregon)
Winemaker Sarah Cabot focused specifically on fruit from Willamette Valley’s 2020 harvest. When presented with smoke-impacted grapes, her first question was whether or not to ferment on skins or go directly to the press. With white varietals, she went directly to the press. Conducting a berry analysis proved to be a good way to determine how much smoke is too much with regard to fermenting on skins.
When making white and rosé wines from smoke-impacting grapes, Cabot found that floating was an effective way to clarify the juice, though it only works if there’s a pretty significant volume. Also, the first eight to 10 gallons were discarded. She succeeded with gentle pressing and pre-fermentation, fining with carbon and bentonite with daily stirring for three days, then settling for three days. In her anecdotal sensory analysis, the pre-fining juice smelled like a campfire, though the post-fining juice smelled good. According to Cabot, spending the extra money on pre- and post-treatment before deciding to bottle is worth it in the long run.
Next, she proceeded with fermentation as usual, adding that this worked best when they chose to go through the process quickly. She took some extra measures during fermentation, finding that there was some evidence that chitosan mitigates the effect of smoke. Also, mannoproteins/polysaccharides, untoasted oak tannins and a vigorous yeast strain with a short lag phase produced high esters. Then she suggested bottling at or above three grams per liter of residual sugar, adding that the higher the sugar, the more pleasing the experience.
When addressing protocols for red wines, Cabot observed that the best sensory analysis results came when using a high temperature with a heavy mace ratio. The more heavily extracted, fruit-forward wines before smoke mitigation treatments yielded the most balanced and enjoyable wines after treatment.
Going into élevage, she kept the free run and press fractions separate, adding that the press fraction required a much heavier treatment. If there are a lot of bound compounds, a winemaker can attempt enzymatic hydrolysis in the tank. By holding the wine at a temperature of approximately 64 degrees Fahrenheit for four to six weeks with regular agitation, the results were anywhere from a 15 to 75 percent reduction in glycosylated markers and a corresponding increase in free volatile phenols on all samples analyzed. While this method proved to be effective for her, she admitted it was a pretty extreme thing to do.
Based on her experience with the 2020 vintage, Cabot concluded that it is possible to make an enjoyable, early-release wine from smoke-affected fruit at a slightly higher final production cost that people will enjoy. With red wines, especially pinot, a heavy extraction approach yielded the best post-treatment result. Also, the commonly publicized “Best Estimate Sensory Thresholds” for VPs seem accurate according to most tasters. In the event of another smoke event, Cabot would stick with the early release and early consumption wines. Also, she would repeat her decision to produce only the sub-$25 SRP pinot noirs due to insufficient data on the long-term bottle aging effects of smoke markers.
For Additional Information
Those wishing to delve further into the burgeoning research into sensory analysis that includes information on smoke-impacted wine should check out Elizabeth Tomasino’s work as associate professor at Oregon State University: Department of Food and Technology (https://foodsci.oregonstate.edu/users/elizabeth-tomasino) and the Oregon Wine Board: Wildfire Smoke Toolkit (https://industry.oregonwine.org/resources/toolkits/wildfire-smoke-toolkit/). Among the recommended labs for their work with smoke-impacted grapes include The Australian Wine Research Institute (https://www.awri.com.au/), ETS Labs (https://www.etslabs.com/) and UC Davis College of Agriculture and Environmental Sciences (https://caes.ucdavis.edu/).
