Tuesday, March 5, 2013

Wine, Weather, and Smoke

Remember the extensive wildfires east of the Cascade crest last summer?  Will you be tasting a bit of it when you enjoy your favorite Washington or Oregon wine with a 2012 vintage?

At the Northwest Weather Workshop last weekend, there was a nice poster by Dr. Tes Ghidey of the AgWeatherNet group headquartered at Washington State University (WSU) and it stimulated my interest in this important question.

At the tail end of the historic August-September 2012 drought a number of significant wildfires were initiated by lightning and human causes, the most famous being the huge Taylor Bridge fire near Ellensburg.  The following MODIS satellite image is for September 24th.  The red dots indicate fire locations.  The smoke is pretty obvious.

According to Dr. Ghidey, September 2012 was central Washington's smokiest since at least 2000.   Large number of small particles were injected into the lower atmosphere, including dangerous small particles smaller than 2.5 microns (millionths of a meter) and a brew of fire-produced chemicals.  I have a joint effort with Dr. Brian Lamb's group at WSU for forecasting air quality around the Northwest, with my group's WRF model forcing the CMAQ air quality model run by Dr. Lamb and Dr. Joseph Vaughn.  Here is the 24-h small particle concentration for September 25th.  A lot of places had concentrations of 35-60 micrograms per cubic meter. That is a whole lot, since reaching 35 represents a serious air quality incident.  And such poor air quality lasted for days and weeks.


So what about the wine?  As documented in a report by WSU, smoke contains high concentrations of volatile chemicals (phenols), such as guaiacol and eugenol, which provide the smoky aroma.  As noted in this report, these chemicals can:

 "accumulate in the skin and pulp of the berry. These compounds are released during ... fermentation, causing the wine to become unpleasantly ‘pharmaceutical’, ‘dirty’, ‘ash tray’, ‘medicinal’, ‘camp fire’, or ‘burnt’, and reduces the perception of varietal fruit aroma."  The term given to this condition is "smoke taint" and grapes are most vulnerable during the week after the onset of vĂ©raison (beginning of ripening of the grape).  Unfortunately, the smoke was at its peak during this time. 

Smoke residues generally concentrate in and can cause discoloration of the grape skins. Thus, the problem is less severe for white wines than for red wines, in which the juice is in contact with the skins for an extended period.  The WSU report talks about a number of approaches to minimize smoke taint. 

At this point I can not find any definitive information about the seriousness of the 2012 smoke taint--perhaps someone in the industry who reads this blog can fill us in.  Smoke levels were highest between Ellensburg (Taylor Bridge Fire) and Wenatchee (Wenatchee Complex Fire), so perhaps wineries in that area will be most affected.  Here is a plot of the concentrations of the 2.5 micron particles during August and September at various eastern Washington locations.  Clearly, Wenatchee and Ellensburg got hit hardest.


 Another issue I have heard is that the reduction in solar radiation associated with the smoke might have lessened photosynthesis and thus reduced the amount of sugar in the grapes.

There was a recent online article by KIRO/MyNorthwest on this subject of smoke tainting of wine, found here.

I very much enjoy Washington State wines so I am hoping for the best.

Some folks are less concerned about a smoky aroma in their wine.
Some folks are less concerned about a smoky aroma in their wine.

5 comments:

Rob W. said...

OK, so I'm not in the industry, but I make wine as a serious hobby. I doubt this will ruin wine, but it will give us a "flavor" of what it means to know the difference between vintages. The whole good year/bad year idea started with the effects of weather on the vineyards of France - some years giving perfect ripeness, some years giving, well, imperfect ripeness, which showed up in the flavors (and therefore enjoyment) of the wine.

Because of "New World" winemaking styles, the growing of grapes in the US in areas that are much less prone to weather variability threatening ripening (the Willamette Valley being an exception), and the industrialization of the winemaking industry, we don't get to experience a lot of year-to-year variation in our wines. I'm actually looking forward to this!

The bigger producers will probably do what they can to minimize the effects, as they strive for consistency of flavor. You'll probably find the effect much more in the smaller producers.

If you want to find the effect (which may be tough to judge at this early point in the winemaking process - remember that wines can pick up "smoky" flavors from being stored in barrels which have been "toasted" on the inside, which most 2012 wines are in the middle of right now), when the time comes, buy three different vintages of the same wine - 2011, 2012, 2013 - from a small producer grown somewhere under the smoke plumes. They probably won't be available in the store at the same time, so this takes planning. Then, with some good friends, open all three bottles at the same time and compare them.

Hindu said...

It was definitely the topic of conversation last summer. Hardest hit growing areas were Wenatchee down to the new Ancient Lakes AVA near Quincy. But even as far south as Tri-Cities spent part of the summer in a smoky haze.

I was told that any taint in the wine would be magnified as the wine aged. So proactive winemakers ran tests at the crush pad looking at different ways to handle the fruit to minimize any taint. Particularly fruit from those northern areas closer to the fires.

I don’t think it will be an issue for the main growing areas in the Columbia Valley, but there may be a little “character” to some of the northern wines.

We should all be vigilant in helping the WA wine industry by testing as much of the product as possible!

Trey said...

We worked with vineyards from the Horse Heaven Hills, Yakima Valley, Red Mtn, Walla Walla, and the new Ancient Lakes, and say absolutely no smoke taint in any of our wines. Our growers were vigilant in even sending grapes out for samples. A non issue in my opinion as I have tasted plenty of 2012's from other producers here in our state and they are stunning wines.

snapflux said...

Rob. W.,

Why is the Willamette Valley in exception? Does it really have more variable weather than other grape growing areas in the northwest?

Rob W. said...

Snapflux -

The Willamette Valley is a more traditionally European wine region. It's not necessarily more variable than Eastern Washington or California, it's more that the expected amount of heat the grapes can use in a particular year is much closer to what's necessary to ripen the grapes grown there.

An example - 2011 at my weather station ran 15-20% cooler than expected for the grape growing season. If the serious rains had arrived in October as typical, there'd been almost no Pinot Noir harvested that year, while in eastern Washington and California I suspect that there was no real concern.

Luckily for the Willamette growers, the rains held off for almost a month, which allowed for the grapes to slowly climb into acceptable ripeness range.