Research Group Claims to Have Eliminated Wine-Cork Taint

Daniel Sogg
Posted: June 25, 1999

A group of researchers and cork companies claim to have developed a microwave process that virtually eliminates the cork taint blamed for most cases of musty-tasting wines. The Neustadt Research Institute, Portuguese cork producers Juvenal Ferreira da Silva and Francisco Oller, and the German cork distributor Ohlinger, with some help from the European Commission, spent more than $1.3 million to conduct their study.

The result of their research, which concluded in December, is the DELFIN technique (Direct Environmental Load Focused Inactivation). "The prototype machines reduce taint levels at least 90 percent," said Dr. Jens Jager, supervisor of the project, who said the process had been tested on several million stoppers within the last year. After sensorial and technical analysis of 11,000 treated corks, Jager found that taint levels were practically nonexistent.

Cork taint, which creates off-flavors and -aromas in wine, has plagued consumers and producers for decades. Flawed stoppers damage or ruin billions of dollars of wine every year, and some observers have found a taint rate of 10 to 12 percent.

Taint results from the interaction of microorganisms and chemical contaminants. Current methods attempt to sterilize stoppers by heating them in steam, boiling water or hot air, or by immersing them in a variety of disinfectants. However, these techniques only kill microbes on or near the cork surface and do not eliminate contaminants that were already present when the cork was harvested.

The DELFIN technique, said Jager, kills microbes throughout the stopper. He explained that the intense heat of microwaves drives water to the surface, carrying with it the toxic compounds and volatile contaminants, without damaging the structure of the cork cells.

Nonetheless, Jager's research will certainly be greeted with skepticism in the wine industry. "Some of the wood cork companies have claimed in the past that they solved the taint problem," said Andy Starr, president of Neocork Technologies, Inc., a Napa producer of synthetic stoppers. "Yet taint persists. Ultimately, this or any claimed solution will have to be proven in the market."

Despite the doubters, Jager and the cork companies are convinced that DELFIN corks will revolutionize the industry. A joint patent has been issued to Juvenal, Ohlinger and Francisco Oller, and the companies have invested more than $2 million in production units. Each machine will have 70 separate microwave units and be capable of processing 4 million stoppers per day. DELFIN samples will be available in October, and full production should begin in early 2000, with a yearly capacity of 500 million corks.

To learn more about this subject, read:

Dec. 15, 1998
Plugging Away at Bad Corks

Nov. 15, 1998
Are You Ready for the New Cork?

June 18, 1998
California Competitors Join in Search for Cork Alternative

To read about other causes of corky wines:

January 7 1999
Wood Preservatives Blamed for Corky French Wines