Wildfires are a major threat to the wine industry since persistent exposure to smoke compromises the quality of wine grapes and negatively impacts wines. Currently, these threats are particularly pronounced on the US West Coast, where states such as California, Oregon, and Washington are some of the country’s top wine-producing states.
Now, a team of scientists led by the Oregon State University (OSU) has discovered a new class of chemical compounds that contributes to the smoky or ashy flavors in wines produced from grapes exposed to wildfire smoke. These findings are crucial for winemakers struggling to combat the effect of smoke on grapes at a time when climate change is leading to an increasing number of severe wildfires.
“These findings provide new avenues for research to understand and prevent smoke taint in grapes,” said Elizabeth Tomasino, an associate professor of Enology at OSU. “They also will help provide tools for the grape and wine industries to quickly make decisions about whether to harvest grapes or make wine following a smoke event.”
Previously, changes in wine flavor and aroma were attributed to a class of compounds known as volatile phenols. However, wines with high levels of these compounds often did not taste smokey, while wines with low levels could have such a taste, so volatile phenols did not seem to be good predictors of smoke taint issues.
Now, the experts discovered that these problems are actually caused by a class of sulfur-containing compounds called thiophenols, which are usually not found in wines and other alcoholic beverages, but rather in meat and fish. To clarify these compounds’ impact on wine, the researchers exposed grapes to smoke in the university’s vineyard, and then produced wine from them and assessed their chemical contents. The analysis revealed that, in contrast to wines not exposed to smoke, wines that had been exposed to smoke contained thiophenols.
“To date, volatile phenol concentrations and frequent tasting of potentially impacted wines are the only predictors winemakers can use to determine the level of smoke they might have in their wines. The discovery of thiophenols provides a new chemical marker for smoke taint that could offer a reliable way to identify smoke taint and ways to potentially eliminate it during the winemaking process,” Tomasino concluded.
The study is published in the journal Food Chemistry Advances.