Wildfires Raise Fears Of Grape Smoke Taint
The current wildfires in Washington have left many growers wondering if smoke taint could impact the flavor of their winegrapes.
According to James Harbertson, associate professor of enology at Washington State University, smoke residue contains high concentrations of volatile phenols that have smoky or chemical aromas or flavors. This residue can accumulate in the grape skin and pulp in glycosylated form or, in other words, bound to sugar.
“This is similar to how normal flavor precursors are stored in the grape,” Harbertson explains. “In the case of smoke-tainted wines, the smoky aromas and flavors are released slowly as the wine ages, starting with hints of smoke that can eventually become overwhelming.”
He notes that in oaked wines, sometimes the smoky flavor can marry with the oak flavor and lead to a normal-tasting wine. “But over time, the smoke flavors will dominate, leaving the wines with unpleasant aftertastes and aromas,” he says. He adds that some terms used to describe the flavor of smoke-tainted wine include “pharmaceutical,” “dirty,” “ash tray,” “medicinal,” “campfire,” and “burnt.” These aren’t exactly the flavors winemakers are hoping for.
“The upside is that if wines that will potentially become smoke-tainted are consumed within a relatively short amount of time following bottling, the smoky flavors will not have time to become overwhelming,” Harbertson adds.
Should Washington Growers Be Worried?
Harbertson says no one can be sure at this point whether the wildfires will cause a problem for vineyards and wineries. It’s not clear how near to smoke grapes need to be to be affected, as most of the research surrounding smoke taint has involved controlled burns in closed systems.
However, despite fires and smoke in 2012, wines that year seemed to be unaffected. For this reason, experts are optimistic that this year’s fires won’t have an impact, either. Harbertson points out, though, that many of the 2012 fires were out of state, with smoke drifting into Washington. “This year, the fires are closer to grape-growing regions, so the risk may be greater.”
How Do You Know If Grapes Are Affected?
Growers who want to find out if their grapes are being affected by smoke taint can submit their fruit to external laboratories that are able to check for traces of smoke taint, Harbertson says.
“We highly recommend that growers request information about the glycosylated forms of smoke taint from external laboratories,” he adds. “If the laboratories do not perform analysis on the glycosylated forms, the samples can be chemically treated to release the smoky compounds and sent in with a non-treated sample for comparison.”
Washington State University Enology Extension services can provide more information about this analysis. Interested growers can contact James Harbertson at [email protected].