This September has been horrible for pretty much all of the winemaking regions in California, Oregon and Washington. Wildfires are burning in each of those states and pose considerable danger to this year’s harvest and to the vineyards and the people living and working in those regions. British Columbia’s Okanagan Valley may face risk as well. The physical danger posed by these fires is very real and our hearts go out to all those affected; they are in our thoughts and we are sending up our wishes for their safety.
A far less dire problem is the possibility of the grape crop being ruined due to the grapes, leaves and vines being exposed to significant concentrations of smoke, especially if that exposure lasts for several days or more. But it is still a significant problem.
Prolonged exposure to smoke in significant concentrations can lead to “smoke taint”. Smoke taint is the resulting taste in the wine when the chemical reaction occurs after smoke binds to the grape skins. You probably have never tasted smoke taint: winemakers can analyze the grapes that are still on the vine to see if they have become tainted to a noticeable level. If they have become tainted, they won’t pick them. But winemakers that have tasted wines affected by smoke taint have described it variously as “licking an ashtray”, “wet cigar”, “medicinal” and other variations on smoky. Smoke taint is a problem for producers, not consumers of wine as quality producers will not allow tainted wines to reach the market.
This year is particularly hard on the vineyards for the risk of smoke taint.
In 2017 California experienced wildfires that were massive and destroyed large amounts of vineyard land. The one bright spot in 2017 (if you can call it that) was that the worst of the fires hit around the middle of October. All of the whites had already been picked and many of the lighter-skinned reds had too. So in 2017 much of the crop had already come in by the time of the greatest smoke concentration. This year many of the white grapes are still on the vine and almost all of the red grapes are too.
British Columbia’s Okanagan Valley had some terrible fires in August of this year.
The Christie Mountain fire affected much of the South Okanagan and sent up terrible amounts of smoke. The one bit of good news is that it was largely put out by the third week of August. The risk for winemakers is that the grapes are exposed to smoke after veraison, the term winemakers use to describe red grapes changing colour from green to red. Grapes exposed to smoke before veraison will generally not show smoke taint in the resulting wine. As of the middle of September, the major fires in BC are out, but that does not mean there is no risk of smoke taint. Fires raging in Washington, Oregon and even as far as California are sending smoke up to the Okanagan and that could be a problem for the reds if it lasts. The whites are starting to come in and so there is much less risk there. Washington, Oregon and California are unfortunately going through horrible fires at the time of writing and their wines face a much greater risk of smoke taint this year.
To really understand the risks and effects of smoke taint, you need to understand a little of the chemistry that underpins this phenomenon. Smoke is microscopic particles of burnt material, in this case primarily burnt wood. The smoke particles will land on the grapes and over time can chemically bond to the grape’s skin. They can also be absorbed by the vines and the leaves and transmit volatile phenols (wine geek or chemistry for flavour compounds) to the berries. Washing the grapes off once they are in the winery is thought to reduce the effect of the exposure to smoke. Red wine is more susceptible to smoke taint than white wine. This is because red wine is made by leaving the red grape skins in contact with the juice for up to several weeks in a process called maceration which extracts colour and flavour from the skins and imparts it into the wine. Unfortunately, that can also mean the extraction of smoke flavours as well. White wine is generally pressed and the juice is immediately fermented with very little skin contact. This aspect of the winemaking process makes white wine much less susceptible to smoke taint. No specific grape variety is significantly more or less immune to the effects of smoke taint, researchers have found.
If a group of vines have been subject to smoke in sufficient quantity and duration as to taint them, not much in the winery can be done to mitigate this effect. It is possible to blend small portions of tainted grapes with not tainted grapes into a wine where the taint cannot be detected by humans. As previously mentioned, washing the grapes may help. Reverse osmosis, the act of passing the wine though a membrane, can help as can fining, the act of introducing an agent into the wine which causes particles to cling together and drop out of the wine. Hand harvesting and other forms of gentle handling to minimise rupturing or breaking the skins can help. But these are mitigations only and cannot be relied upon to save a badly tainted crop.
Unfortunately for winemakers, they may not have any insurance against smoke taint. Insurers have claimed that since the smoke taint is caused while the grape is on the vine, this is not an insurable event. Two California wineries have launched a lawsuit against their insurers and the matter is now being litigated.
2020 has seen the confluence of a number of particularly bad factors for the wine industry from California to British Columbia.
First, there is the sheer number and size of the fires. Second is the timing, occurring in that window after veraison but before harvest. Finally, the smoke has fanned out, affecting regions that may not necessarily have been affected by the fires themselves. Big rains and some favourable winds are needed right now to protect this year’s harvest and the land and the people that work to create it. Here is hoping first for the safety of the people affected and then for the chance to be able to enjoy the fruit of their labours.
As if 2020 had not done enough already….