Tainted fruit
Growers take a hit as persistent smoke threatens grapes with compounds that can make wine ‘ nasty’
The Bucklin family’s relationship with Constellation Brands stretches back more than three decades. That’s how long Constellation — a global wine corporation expected to generate $ 7.33 billion in revenue this year, and owner of California wine brands like Robert Mondavi and Ravenswood — has bought grapes from Old Hill Ranch, the Bucklins’ 35- acre Sonoma Valley vineyard. But after this year’s wildfires, for the first time ever, Constellation rejected the Old Hill fruit. The reason? Smoke taint. Throughout Wine Country, as the harrowing 2017 harvest nears its end, small- scale growers like Bucklin are facing a harsh reality: Wineries may not be willing to buy their product because they don’t want to sell smoke- tainted wines to consumers. When that happens, it’s largely not the wineries that take the hit, but the growers.
During the earliest hours of the Nuns Fire, flames ripped through Old Hill Ranch, decimating two homes on the property, knocking
over more than 40 trees and scorching several century- old vines. Most of Old Hill’s grapes had been harvested already, but some — including the parcels contracted to Constellation — remained on the vines. For days, thick smoke lingered.
Constellation’s smoke- testing process takes on a scientific approach, according to vineyard owner Will Bucklin, looking for the presence of the chemical compounds guaiacol and 4- methylguaiacol, which contribute smoky aromas and flavors.
“They tested the grapes before they were set to pick and found the compounds present,” Bucklin said. “And they rejected the grapes based on that.”
Bucklin does not have crop insurance, which would probably have helped recoup some of his financial losses because of the smoke, on Old Hill Ranch, originally planted in 1852. He’s planning to get insurance now.
To help soften the blow, Bucklin decided to make Constellation’s rejected fruit into wine himself ( in addition to farming the vineyard, he owns a small, eponymous wine brand), though he’s not sure whether he’ll be able to sell it as wine, either bottled or in bulk. Some Cabernet Sauvignon is tasting good, but one of his lots — an Alicante Bouschet grape variety — is already, as he put it, “nasty.”
In Napa Valley, grower Maria Haug is waiting to see whether the last of her fruit, some Roussanne grapes, will be rejected.
“We’re just hoping the numbers come in low,” Haug, who with her husband, Rene, farms a 7 ½ - acre vineyard in Rutherford, said of the pending smoketaint analysis. About 90 percent of the Haugs’ grapes had been picked before the wildfires; the final 5 tons of Roussanne were picked Oct. 26. The day before that pick, the winery client ( whom Haug did not name) made Haug sign a contract saying that if the grapes tested positive for high levels of the smoke taint compounds, the winery would not have to pay Haug for the fruit.
If the winery does reject the fruit, Haug will take the grapes, vinify them at a custom- crush facility and attempt to sell the wine on the bulk market. “But we don’t make money that way, we just cut our losses,” she said.
Custom- crush fees come to about $ 1,000 per ton, she added, plus the costs of pruning, picking and farming; she estimates she might get $ 1,000 to $ 1,200 per ton on the bulk market. The Napa County average price of Roussanne, meanwhile — the price the winery would pay her — was $ 4,250 per ton last year.
What, precisely, is smoke taint, and how can grapes be tested for it?
“There’s a lot of confusion on the topic, and not a lot of research has been done,” said Robert Tracy, owner of BevTrac Mobile Quality Systems, a Windsor company that provides quality assurance consulting services to the wine industry. “What happens is that when smoke is produced from fire, there are lots of volatile compounds that get in the atmosphere, and there’s probably eight that could then get into grapes.”
Of those eight compounds, two — guaiacol and 4- methylguaiacol — are considered the main smoke taint culprits, and can be tested for. Both can occur in wines normally. They help contribute Syrah’s signature smoky aroma, for example, and often appear in high concentrations in wines that have been aged in toasted oak barrels.
When smoke lingers, guaiacol and 4- methylguaiacol can penetrate grape skins. “They actually stay in the skin primarily, and sometimes in the pulp,” Tracy said. However, those volatile compounds can bind to the sugars in the grapes, rendering them nonvolatile. Volatile compounds can be smelled; nonvolatile ones can’t.
According to Tracy, most laboratories can test only for free guaiacol and 4- methylguaiacol. But if the compounds are bound and therefore nonvolatile, neither a laboratory test nor a human nose will detect it. More complications can ensue, because bound compounds can get released later, especially during fermentation.
“That’s why you can have low levels of the compounds at the juice stage, but higher levels at the wine stage, because the bond between the sugar and the smoke taint chemical is broken,” Tracy said. Glucosidase enzymes that break those bonds, he added, are present in the human mouth, so it’s possible that smoke taint compounds can be freed by the act of tasting.
In other words, there may be no way of telling how much smoke taint will appear in a wine down the road.
To make matters more confusing, no standard definition exists for what constitutes too much guaiacol and 4- methylguaiacol in grapes, and when a winery shouldn’t make wine from them. Multiple winemakers cited 0.5 parts per billion as the safe threshold, but Haug believes her winery client will not reject her Roussanne if it tests under 23 parts per billion. ( White wines, theoretically, should be at a lower risk of showing smoke taint than reds, because the juice typically spends little time exposed to grape skins.)
For Will Bucklin, the fate of the rejected Constellation grapes is unclear. Maybe he’ll sell the wines on the bulk market — though he doubts that even the bulk market would accept smoke- tainted Alicante Bouschet. Maybe he’ll apply techniques like reverse osmosis, which has been shown to potentially reduce smoke taint, though he’d consider that a last resort.
Maybe the wines will turn out just fine.
“I really, strongly feel that I want there to be some character about the fire in the wines,” Bucklin said. “This is part of the vintage, and it’s going to be a part of my life, remembering this event. In 10 years, if I sit down and have a bottle of that smoky Cabernet, I want to remember the vintage.
“At the same time,” he said, “I don’t want the wines to be disgusting.”
Maria Haug, meanwhile, counts her blessings. Her family has been farming its vineyard since the 1940s, and in her lifetime she remembers only two vintages — one in the early 1970s, the other 2011 — where the family had to take a loss on contracted fruit.
“It’s farming, and farming is always a gamble,” Haug said. “I think a lot of people that are new to the industry may not remember that Napa Valley has had an awful lot of good years.”