August 2018 Issue of Wines & Vines

Automating Cork Quality Control

Major cork suppliers invest in new technology to catch contaminated corks

by Andrew Adams

At one of Silver Oak Cellars' release-day parties in 2008, the winery had dug out a 6-liter bottle of Alexander Valley Cabernet Sauvignon from its library.

In front of an expectant crowd of Silver Oak fans, a winery staffer pulled the thick cork from the neck of the oversized bottle, and the smell of disappointed anticipation was overpowering.

"We pulled a really corked cork, it stank of TCA to the high heavens, in front of literally dozens of people," recalled associate winemaker Christiane Schleussner. "It was highly embarrassing."

Word got back to ownership, which quickly sent word back down the production chain to ensure that every large-format bottle was sealed with a clean cork. The task fell on Schleussner to figure out how to do it.

She got in touch with a cork-quality scientist in Portugal who directed her to a researcher in her native Germany. The two corresponded on a potential method to analyze corks for any flaws without destroying the corks. That initial correspondence led to a collaboration, and the two eventually published two academic papers on what would become known as the "dry soak" method of analysis.

Schleussner worked with Cork Supply to develop the method to validate all of the more than 2,000 large-format corks she needed for Silver Oak. The success of those early trials soon led to Cork Supply developing what's now known as the DS100 protocol.

From human to machine sniffing
Cork Supply's headquarters is outside of Porto, Portugal, and when Wines & Vines visited in 2017, the main lobby of the building was crowded with white-coated lab techs silently working at long tables covered with cork samples. The techs were sniffing each sample, trying to detect any aromas of cork taint or any other off-putting aromas that could result in a flawed bottle of wine. A similar scene can also be found at the company's building in Benicia, Calif., where Cork Supply USA is located.

But the headquarters in Portugal is also home to a new type of natural-cork quality-control process that is still relatively new and offers the same level of guaranteed protection from TCA. Cork Supply now has six machines that run an automated screening process, which the company says, coupled with its human-powered screening process, will enable it to supply 10 million to 15 million corks that it can guarantee will not cause any problems.

Such machines were introduced recently, but it has taken some time for them to achieve throughput rates that could warrant commercial distribution.

In addition to Cork Supply, the world's largest cork company, Amorim, now has what it calls its NDtech system that screens individual natural corks that are then guaranteed by the supplier. The NDtech corks are also available in the United States through Amorim's subsidiary, Portocork, and sold as ICON certified.

Lafitte Cork & Capsule, based in Napa, Calif., is now selling its highest-grade corks that have undergone individual sensory and laboratory testing through its Electvs program with a 100% guarantee. M.A. Silva USA in Santa Rosa, Calif., is also developing what it calls the "onebyone" system to deliver individually inspected and guaranteed corks.

Scott Laboratories in Petaluma, Calif., recently unveiled its Scott Plus line of corks, which the supplier reports have undergone an additional layer of screening on top of the standards it applies as an independent buyer of corks. The additional screening consists of sensory and automated analysis with improved processing. The company describes the program as a significant step toward reaching its goal of being TCA-free by 2020.

Expanding automated analysis
At Cork Supply, the company had an operational cork-screening machine in 2017 and has since added five others that improved on the first working prototype, said Greg Hirson, the company's senior director of technical services.

Those improvements included changes to how the machines operate and how the corks move through the screening process. The detection process is a proprietary one developed by Cork Supply that involves a cork entering a chamber where it is warmed slightly. Any volatile compounds released by the cork are collected in the chamber and then concentrated to provide a sufficient sample for analysis. Rejected corks are culled from the production chain.

Hirson said Cork Supply is now filling orders of corks processed through what it's calling the DS100+ process but in relatively small number as the company continues to evaluate and improve the machines. "We're still in the process of making sure what we're putting out in the market meets our quality requirements," he said. "We're working as quickly as we can, given we have these high standards of quality."

Corks that have gone through the human-powered screening program, DS100, remain in high demand from winery clients, so Hirson said Cork Supply wants to ensure the machines deliver the same level of quality.

The average rate of rejection from the DS100 system is about 8%, and Hirson said the machines are at a higher rate because the standards are much tighter as the automated process is further refined. Rejected corks in Portugal are typically used in other products such as flooring, and in the United States, Hirson said, most are being collected by nonprofit groups and schools that use the corks for craft projects.

Schleussner didn't foresee the development of automated screening machines but said it makes sense because the analysis itself isn't that difficult; it's the automation at a high rate of precision and speed that would be a challenge.

Silver Oak has purchased a significant number of individually screened corks for bottling this year, and Schleussner said those corks came from Cork Supply, Amorim, Portocork and Scott Labs. She said the winery already expects few problems because ever since that badly tainted imperial, Silver Oak has reduced its rate of corked bottles to less than 0.5%.

She said she's no longer concerned about the "real stinkers," but is still concerned about the corks on the threshold of perception or others contaminated by different compounds that may not register as TCA. A career working with analytical equipment has also taught her that machines can fail to perform as expected.

Amorim's director of marketing and communications Carlos de Jesus said that since the NDtech program launched commercially in 2017, Amorim has supplied a total of 20 million corks processed through the system to 1,200 wineries around the world. U.S. wineries have received about 12 million corks. De Jesus said the company is trying to add production capacity as quickly as possible, but it's not simply a matter of adding more machines but rather better code so that the analysis can be done more quickly. "It is very difficult to be able to perform that kind of analysis in seconds as opposed to minutes," he said. "We are now down to below 16 seconds, and the plan is to bring that down further this year."

De Jesus said Amorim's efforts have been rewarded by not one, but two, global insurance companies willing to back the company's guarantee behind every cork certified through the NDtech process.

He said demand from wineries selling at the highest price points has been strong, as expected, but what was not as expected was the high interest from wineries at the $30 to $40 per bottle level. The certification process can add 12 to 15 cents per cork or $145 to $175 per lot, and de Jesus said it appears wineries are willing to pay the premium to use a fully guaranteed natural cork.

It's the conclusion reached by Michael Hirby, who is the winemaker and owner of Relic Wine Cellars in St. Helena, Calif. Relic produces around 2,000 cases per year, and after conducting a trial of certified corks, Hirby is now bottling everything under them. "I think it's a reasonable price to pay considering the guarantee and being able to sleep better at night knowing every wine we put out will be at its best."

A former sommelier who transitioned into winemaking, Hirby said all of the world's greatest wines throughout history have been sealed by cork. While there may be some other closures that could provide similar quality over time, Hirby said, the industry just doesn't yet have a sample of truly great wines that have been under those closures for decades.

And considering the name of the winery is "Relic," Hirby said, the prospect of a natural cork with a guarantee of protection just made sense. He said his trial consisted of a small bottling lot that he evaluated over time. "We've just found six months out and a year out, just really, really great consistency."

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