Cellar Sleuths: The Case of the Cork Taint Stink

Call it CSI: Napa Valley Edition, because what cork taint can do to wine is a crime. Once you’ve smelled the musty odor of wet dogs or damp paper in your glass, you can’t forget it.

In the case of cork taint, the CSI techs are the Shafer Vineyards winemaking team. They’ve spent over 20 years sussing out clues to the defeat of this notorious wine cellar offender. Using sophisticated techniques like laboratory forensic analysis—and old-school tactics like following their noses (literally)—they’ve investigated everything from storage pallets to corks to barrel construction.

And now they’re just about ready to close this (wine) case.

“The future of Shafer wine is TCA-free,” says Doug Shafer, winery president.

Your nose knows

How do you know if you have a corked wine? Some research indicates people with unusually sensitive palates can detect it as low as two parts per trillion. Some don’t notice it until it’s reached much higher concentrations. For reference: one part per trillion is like a grain of sand in an Olympic-sized swimming pool.

If you ID the flaw, you can usually get a replacement bottle from the wine store or producer. What keeps winemakers up at night is consumers who may just think their wine isn’t particularly good and move on to a different brand.

On the trail of TCA

Like most bad actors, cork taint goes by a couple of aliases. You may know it as TCA; if you’re a next-level wine geek, you may even know that’s an acronym for the chemical compound 2,4,6-trichloroanisole. (Personally, we always have to look that one up.) This substance is harmless to humans but death to good wine, leaving behind the infamous odor.

Cork gets the rap for TCA, but it’s not always the perp. TCA loves to make a home anywhere porous and organic. This includes wood and cardboard, both found in abundance in most cellars.

“Once we started really looking for it in 1990s, we found more and more places where TCA could be present in the cellar,” says Shafer winemaker Elias Fernandez. “The difficult thing about TCA is that it hides in places you don’t even think to look.”

Out of the woods

The first thing the team did was to get rid of wooden pallets for storage, replacing them with plastic pallets. Then wooden barrel racks were ditched for stainless steel. Even the wooden wedges used to hold barrels in place were replaced with aluminum ones.

Because chlorophenols like TCA can result from the use of the chlorine as a sterilizer, the winery stopped using chlorinated water and found new ways to clean tanks and equipment.

They also switched up their cork game, using purified corks from French producer Diam for the Shafer Red Shoulder Ranch Chardonnay and Merlot. On wines that likely will be aged, including Relentless, One Point Five Cabernet Sauvignon and the flagship Hillside Select, Shafer is using traditionally made corks that have been individually tested for TCA.

Roll out the (revamped) barrel

Their latest breakthrough has been to change the way their barrels are made. Traditionally, a thin layer of flour paste is used to seal the head. Fernandez fingered the paste as a potential source of mold and worked with barrel maker Demptos, in Napa, on barrels sealed with a neutral paraffin wax instead.

Is the case closed?

In the average week, says Shafer, the hospitality team opens and pours about a case of Shafer Red Shoulder Ranch Chardonnay. In the past, they saw TCA spoilage of just under one percent. Since making the various changes and the cork switch with the 2013 vintage, “we’ve gone to zero and the same is true for the 2014 vintage as well.”

Shafer’s hoping he and his team have put TCA away for good.

“We’ve been working toward this for a long time and are thrilled to reach this historic point,” he says.

Taste (and smell!) the results of Shafer's TCA investigation:

Michelle Locke is a photojournalist in the San Francisco Bay area specializing in food, wine, spirits, and travel. In other words, all the things that make life fun. She is a contributor to the Associated Press and columnist for Palate Press, the online wine and spirits magazine Palate Press, and develops, writes and photographs stories that appear in publications nationwide. Yes on Oxford comma.