The Peril of Smoke Taint on Winegrapes

Wildfires Threaten Smoke Taint on Winegrapes

By Charmayne Hefley, Associate Editor

There are at least two dozen major fires burning in the wilderness of California. Many are now contained, while others are only minimally contained. One recent serious fire, known as the “Rocky Fire” in Lake, Yolo, and Colusa counties burned nearly 70,000 acres before firefighters extinguished it last month.

But smoke from that fire may yet cause problems for the wine grape industry in Napa, Sonoma, and Lake counties. James Kennedy, chair of the Department of Viticulture and Enology and director of the Viticulture and Enology Research Center at California State University Fresno, explained the threat of smoke taint on winegrapes. “Anytime you have wildfires near vineyards,” Kennedy said, “there is a concern about how that smoke might become associated with grapes, and as a result, become associated with wine.”

Kennedy said they learned a lot about this problem from the Australian wildfires in 2003 that tainted their wine. Kennedy explained,“grape growers are oftentimes not aware of the extent to which smoke can damage fruit. In a sense, it is a two-edged sword. When wine is made from smoke-tainted grapes, it will have characteristics reminiscent of ‘the morning-after ashtray’ that is quite obnoxious and certainly not desirable. The other side of the sword occurs when smoke compounds interact with the grapevine and grape berries, it is modified by the grapes. Like an iceberg in the ocean, the ice above the water suffers the apparent smoke taint; whereas, the massive chunk underneath the ocean, though not initially as obviously smoke-tainted, reveals obvious taint over time.”

Kennedy said, “Winemakers in Australia realized that while you can treat that initial smoke taint, you don’t resolve the long-term taint problem. We, as an industry, are trying to identify vineyards with smoke taint problems before their fruit is made into wine. By testing grapes in laboratories, we are trying to prevent those wineries from wasting significant investment in converting tainted fruit into tainted wine.”

The Napa Valley Vintners nonprofit trade association reported on its website yesterday, “So far no vineyards or wineries in Napa County have been threatened by any of this season’s wildfires. Most of the time the fires were burning, the smoke blew away from Napa County due to the typically prevailing winds from the southwest. The weekend of August 15/16, we did experience very hot temperatures and a wind shift that caused our air to be hazy and smoky as a result of the many fires burning throughout CA. However, there were no reports of smoke taint affecting Napa Valley wine grapes as a result.”

“Most reports on smoke taint indicate that it exists only after an extended period of close contact with smoke; conditions that have not, to our knowledge, existed within Napa Valley this summer. Furthermore, Napa Valley is known for the highest standards of fine wine production and our winemakers will be paying very close attention to this situation as they harvest grapes for the 2015 vintage.”

Forest Fires Could Be Impacting Winegrapes

Smoke Taint Could Cause Off-Flavor Vines

Many forest fires throughout California have been near or upwind from many winegrape vineyards and could be causing problems for the grapes.

Jim Kennedy, a professor and chairman of the Department of Viticulture and Enology at the California State University of Fresno, explains a particular serious problem due to smoke enveloping vineyards.

“A lot of these fires are getting very close to the wine industry, and that’s a problem because the smoke that these fires generate, they come in contact with clusters of fruit. The compounds that are smoke get absorbed onto the fruit and the plant likes to modify these compounds, because it can be quite toxic to plant cells,” said Kennedy. “The wine gets made from that fruit and the wine ages, the smoke compounds become released again, and it’s a real problem. Your wine starts to resemble an ashtray, its smell and character,” he added.

Kennedy said the tragedy is that the fruit is exposed to the smoke and it’s not readily and obviously upfront as problematic.

“A winemaker goes through the wine-making process thinking their fruit has escaped the problem, and low and behold a year down the road its become an ashtray. And that is something as the grape and wine industry we’re really keeping an eye out on these forest fires, and consulting with winemakers in these different regions so they are aware that this is a potential issue,” said Kennedy.

Kennedy said that this problem, also known as “smoke taint” has been seen many times.

“The classic sample is Australia. With the bush fires in Australia a lot of the vineyards are very close to eucalyptus groves, and so there’s a lot of research that has come out of Australia in terms of how to measure the potential for smoke taint in fruit and how to deal with it once you got it. The Australians tend to be on the front-end of it because it’s an issue that has much more potential for disaster in their industry,” said Kennedy.