August 2014 Issue of Wines & Vines

Keeping Corks Free of Contaminants

Supplier techs sniff individual corks for high-value wines as work on automated TCA-screening systems continues

by Andrew Adams
Cork sample evaluation
Prior to a bottling in April, Brown Estate evaluates cork samples.

It’s one of those rare things in the wine business that’s regarded by everyone from winemakers and sommeliers to consumers with the same mix of disappointment, annoyance and even embarrassment: the eagerly anticipated bottle that ends up corked.

“Obviously you know every time you open a bottle and you get that corked, musty smell, and your wine is ruined. It’s just totally disappointing,” says winemaker David Brown. “And it always seemed to happen to me when I was trying to show off our wine.”


  • Fed up with corked bottles, one Napa winemaker opts for a testing method that costs more per cork.
  • Three major suppliers continue work on automated quality-control systems for corks.
  • Portocork is launching a study about how aroma flaws detected through sensory analysis can affect wine.

Brown, who is part-owner of Brown Estate winery and vineyards in the Chiles Valley area of Napa Valley, said he was growing ever more frustrated with faulty corks. He said corked bottles were something he kept note of but didn’t record each and every time he, a tasting room staff member or customer reported coming across a bottle that was corked. However events like the Zinfandel Advocates & Producers’ annual tasting, where he’d open 10 to 14 cases of wine, gave him a good insight into the scope of the issue, and after noticing an uptick in the rate of a corked bottles at a recent tasting he decided he had to do something—especially since he was buying corks purported to be of the best quality.

A barrel representative mentioned the DS100 program by Cork Supply, and Brown decided to give it a try. Cork Supply’s program involves putting each cork that’s part of an order through the non-destructive “dry soak” method of sensory analysis.

Brown thought it probably wasn’t going to be 100% effective, but he figured it was better than doing nothing.

A premium service, but less cork anxiety
Brown said the incidence of corked bottles is way down, and taint wasn’t an issue at all at the 2014 ZAP tasting. He said the dry soak service costs more, and it does add extra time to bottling because analysis time needs to be added to the schedule, but he feels it’s worth it to preserve wine quality. After all the investment in the vineyard, cellar and packaging, it just doesn’t make sense to put everything at risk by using a tainted cork. “We pay good money for each cork to be analyzed by hand,” Brown said.

In the August 2013 issue of Wines & Vines, the story “Advances in Closure Quality” reported on Cork Supply and Portocork’s separate efforts to develop automated processes and machines to analyze corks for TCA and other contaminants. The goal at the time was to provide the same accuracy and certainty of individual, non-destructive sensory analysis—but at high speeds.

Last year the hope was to have something ready by now, but it appears the industry will have to wait another year. “We’re still cranking away at putting that technology together,” said Peter Hladun, director of technical services at Cork Supply USA, who added the goal is to have a system in place in Portugal by next year.

In the meantime, the company has ramped up its DS100 program, and Hladun said they’ve tested 2 million corks so far in 2014. That’s a 150% increase over last year. He said Cork Supply continues to purchase hardware and hire sensory technicians to increase the capacity of its DS100 program, which can currently process 10,000 corks a day. The service costs 30 cents per cork, and Hladun said 75 wineries are using it. Most of these clients are high-end producers bottling wines with a retail price of more than $100 per bottle. Many are based in the Napa Valley, but a few clients are in Oregon and Washington state. Hladun said several wineries only use the DS100 service on corks destined for their very best wines, or they just use it for large-format corks.

He said three full-time technicians conduct the analysis. A team of two techs will sniff each sample jar and if either of them detects TCA (or any other off aroma) the cork is immediately rejected. “We don’t discuss whether someone got something or didn’t,” he said.

All of the approved corks are then audited by a third tech to ensure they’re clean. Hladun said techs essentially need to score perfect on a standardized “duo-trio” test for TCA to work on the DS100 program.

He said the company has plenty of space for its DS100 analysis, it’s just a matter of buying the hardware, glassware and hiring the right staff. A few equipment upgrades have helped as well. Hladun said Cork Supply developed a process to heat the sample trays and create stronger, cleaner aromas for the sensory staff to analyze.

Dustin Mowe, the president of Portocork America, said Amorim & Irmaos SA (a subsidiary of Corticeira Amorim) is develoing an automated inspection system at the Portocork facility in Portugal. “We continue to work on this,” he said. “We have a machine that works, that is operational. Our biggest problem has been throughput—being able to put out enough corks.”

Mowe said the company is planning to make a “significant investment” in the technology to reach production scale, and equipment could be in place to screen the company’s top-quality corks by April 2015.

He said the individual sensory analysis method remains an excellent choice for preventing TCA contamination, but a significant number of corks are removed or “kicked out” for a variety of sensory flaws such as aromas of jalapeno pepper or ashtray, although it’s not clear exactly what could happen to the wine when sealed with corks displaying these attributes. Mowe said his staff at Portocork has begun a long-term study in which the rejected corks are used to seal
a neutral, white wine. Regular tastings will be held every six months, with winemakers and a few wine writers participating to evaluate how the rejected corks affect (or don’t affect) the wine. “I think this will be the first huge (development) that tells us how important it is to kick out these things with sensory,” he said.

Lafitte Cork & Capsule currently offers individual sensory analysis—but only for its large-format corks, said general manager Mark Hautala. He said the process is a very reliable method for detecting TCA, but it’s not particularly worth the time and effort for an order of several thousand or tens of thousands of standard corks. “It’s really the time, because with the levels of TCA that we see on incoming lots it almost doesn’t make sense, quite frankly,” he said. “We’re down to less than 1% now.”

As a member of the Cork Quality Council, Lafitte—as well as Amorim Cork America, Cork Supply, Ganau, Scott Laboratories, Portocork and M.A. Silva—conduct rigorous testing at the supply source as well as when they receive corks in the United States. Testing involves pulling samples from cork bales for gas chromatography mass spectrometry (GCMS) as well as other tests to ensure corks meet size and quality standards. Hautala said Lafitte conducts additional quality testing for every bale of the top three levels of quality corks it buys.

He said Lafitte is also working with research partners to develop its own automated system for individual cork analysis and is close to having something ready soon. “We’re working on some things,” he said. “We do see it trending in that direction where one day there will be individual testing without human sensory.”

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