The LNU Fire Complex
Our little corner of the world made the national news for the wrong reason this summer: fire. In mid-August, California’s fire season started early when ocean-bound heat from inland met with the wet remnants of a tropical storm from Baja California. The result was lightning strikes all over the state that started so many fires our Department of Forestry, called CalFire for its main mission, didn’t even bother naming them. Instead they lumped them into “complexes,” such as our LNU Complex (LNU = Lake-Napa Unit). Our portion of the LNU Complex did get a name, the Hennessey Fire, named for a ridge above Lake Hennessey where the fire started. That ridge is to the east of Napa Valley, and the fire mostly burned to the east. It caused immense destruction but the area is lightly populated. Still, we know too many who lost their homes and livelihood.
A Primer on Smoke-Taint and its Analysis
Though that fire burned away from Napa Valley, its smoke still came our way. “Smoke taint” in wine has been an all too common occurrence in California since at least 2008. Australia has been coping with it for even longer, and is leading the way in research on the issue, though UC-Davis and researchers in Washington State are quickly catching up (and collaborating with each other and with Australian researchers). That said, the phenomenon is still mostly mysterious. We know that it is not, or at least not only, a surface problem. It is probably wise to wash ash and smoky residues off grapes before processing them for wine, but while that may help it will not solve the problem. We know that when grapevines are exposed to smoke, they actively take up malodorous compounds and translocate (that is, move) them to the grapes. Why they do that remains a mystery. When the nasty compounds get to the grapes, the berries glycosolate them, meaning that they attach a glucose (sugar) or similar “moiety” to the offensive compound. That renders the compound non-volatile, and therefore not detectable by taste or smell. The berries still hanging in vineyards as I write this taste amazing! The problem is that in the acid conditions of fermentation the glucose bond to the offensive compound is broken, making the compound volatile and therefore detectable again.
Good for you if you are still with me! I apologize for my vagueness. Why do I keep writing “compound” rather than naming the offensive agent(s)? Because we don’t know what they are. We know that levels of guaiacol, a small phenolic compound found in cloves, are elevated in smoke-tainted wines, and guaiacaol is easy to test for. So guaiacol and the closely related 4-methylguaiacol are part of the panel of compounds we search for when we try to determine whether our grapes have been impacted by smoke. But guaiacol itself does not smell like a stale ashtray, and many wines that are not affected by smoke taint have high levels of guaiacol (and 4-MG).
Disputes Among Laboratories about How to Test and What to Test for
On a geeky sidenote, there are a number of labs doing testing in berries and wines to determine the level of smoke taint. They each have different methods and the philosophies behind each are compelling. Should the lab just measure free (unglycosolated) compounds, or should it also induce hydrolysis to measure the bound (glycosolated) precursors that could lead to nasty smoke characters? What if the process of hydrolysis itself creates the markers for smoke taint (such as guaiacol and 4-MG) from non-smoke related precursors such as the tannins and pigments naturally present in all wine grapes, tainted or not? If you would like to know more about these debates, let me know and I’ll happily geek out with you and forward resources your way.
The short version of the story, though, is that at this point the tests are not a perfect predictor of whether a wine will turn out to be undrinkable.
The Aftermath of the LNU Complex Fires
The LNU Complex fires began on August 17, about mid-way through the harvest of white grapes in Napa Valley, and well before most grapes for red wines would have been harvested. Fires aside 2020 was shaping up to be a somewhat later than normal vintage. The early August heat that made the LNU fires so likely was the first big heat we had had all summer. The growing season had otherwise been quite moderate.
Although we often get such heat events in Napa Valley, for some reason Cabernet Sauvignon handled the August heat spike particularly poorly. The Cabernet vines in Oakville from which I make The Albatross Cabernet Sauvignon started crashing in late August. Since we typically pick those grapes in early- to mid-October, this was not good. Putting scarce water on the vines didn’t seem to help. They were simply shutting down. Driving out to assess the situation, I saw that the problem with Cabernet was widespread throughout the Valley, even in the famed To-Kalon vineyard at the foot of the hill where “my” grapes grow.
At Benessere, my day job, the Cabernet was also suffering, and we brought some into the winery earlier than ever before. But let’s back up a bit.
The local lab in St. Helena was already slammed with berry, juice and wine tests for smoke taint. The test takes 2 days to get results, but there was such a backlog that results were taking 5 days, then 10, then 20, then longer to get results. Hard to base picking decisions on that. I learned of a lab in the Okanagan Valley in Canada, one of Canada’s premier winegrowing regions, that offered much quicker turnaround time. We took berry samples of the various blocks at Benessere and sent them off. Results arrived a few days later and they were promising.
At the same time, we started microfermentations: 2-gallon lots from each variety in our vineyard. The idea was that if the resulting wines showed off aromas we would know that the grapes were tainted and there was no point picking.
Based on the Canada lab results and our microfermentations, we felt pretty good about the harvest. In came the grapes.
Bad News—and Why Smoke Taint is Really Nasty
When the fermentations were just over half-way done, the ugly signs of smoke taint revealed themselves. One lot smelled like a stale ash tray. Another smelled okay, but left an awful feeling in the throat as if you had just taken a gulp from a coal tailings pond.
I get well meaning suggestions all the time for how to use our affected grapes. Make barbecue sauce! Make jelly (smoke jelly?)! Don’t barrels impart a smoky flavor—maybe you can save money on barrels this year! Thanks for all the suggestions and, yes, the barrels we bought this year will not be used until next year, so we will save money that way. But folks, this stuff is nasty. Don’t think “pleasant evening by the fire,” think “someone dropped a cigarette butt in this beer,” or “who lit a tire in the living room?” This is not a pleasant phenomenon.
The Time Factor
Acid hyrdolysis liberates most of the bound precursors during fermentation, so by the end of fermentation you should know if you have a problem, right? Well, it’s not that simple. Remember we still don’t know what we are dealing with. (Mostly) all of what we have is anecdotal evidence, and it is not encouraging. Wines that are fine today can be horrid 6 months from now. Wines that have been treated for smoke taint (see below) can revert to that horrible state months or years after treatment.
Then What? The Glass Fire
At Benessere we had already pulled the plug on the 2020 harvest when the Glass Fire spiraled out of control. This one started in the hills east of the Valley floor but on the Valley side. High winds spread embers like mad, and even though CalFire threw everything they could at it, including two bombers (dropping flame retardant) and a bevy of helicopters, which took water from Benessere’s pond along with many others, the fire was at 0% containment for several days. We evacuated the morning after the fire started in the dark of pre-dawn. Only it wasn’t so dark because flames burned right up to both shoulders of Highway 29. We saw power lines burning. Even the cable car wires at Sterling, which would otherwise have been invisible at that hour, were brightly ablaze.
It was terrifying, but in terms of winemaking it meant that everything was on hold. All UpValley roads were closed, and with good reason. The County issued Ag Passes for workers who needed to get by road blocks. Benessere was able to do what was needed to keep from losing the wines already in tank. Having evacuated on Monday, September 28, we were not allowed home until Monday, October 5. Now things are as normal as can be in a Valley that has witnessed so much destruction.
Treatment—Isn’t There Anything to Be Done?
No. There isn’t. Activated Carbon can work miracles, and it can remove smoke taint characteristics, at least in the short term. The problem is that carbon removes a great deal else besides. Maybe the wine doesn’t taste like Eau-de-Ashtray anymore, but what does it taste like? Not much. There are various proprietary reverse osmosis (RO) techniques, and more coming all the time. RO works by very specifically binding to known compounds and pulling them out of solution. That’s great if you know what the compound you need to remove is. Not so great if you don’t. It is with RO treatment in particular that the smoke taint characters are known to return in a treated wine. When you don’t know what you are dealing with, it is hard to deal with it. I guess that’s the moral of every horror movie out there.
What did PWR do?
Some good news first. We made a Viognier this year from a vineyard new to us, and we harvested well before the LNU fires started. White wines are generally less susceptible to taint, mostly because they spend so much less time in contact with the skins where the offensive compounds are stored. But this is a straight up winner.
We also made some Rosé this year. Those grapes were picked after the LNU fires but before the Glass Fire. Thanks to limited skin contact, it seems like the Rosé is fine.
We made a Syrah from a vineyard in the Petaluma Gap that we have been drooling over for years. The wine has completed fermentation and it smells and tastes great! Will smoke taint materialize over time? I sure hope not, but all I can do is hope.
Similar story with our Oakville Cabernet. Our fingers are crossed!
What You Can Do
If you have read this far, you are obviously concerned and I thank you for that. We—PWR, Beatrix and me—are fine. Many in our Valley are not. You can help financially by buying any wine produced in Napa Valley. For more specific help, you can donate to UpValley Family Centers and Community Action of Napa Valley. Both organizations are helping people who have lost their homes, their possessions, their jobs, and more.
Also, please vote. I can’t imagine that any of you are not already planning to participate in this election, but if somehow one of you is not, please reconsider. Fire is a natural phenomenon, but these fires are as much the result of human-induced climate change as they are anything else. For far too long we have been aware of the science of climate change and have hidden our heads at best, denied it at worst. That must change. And to paraphrase, the best time to do something about climate change is 30 years ago. The second best time is now.