How do you know if a wine is authentic without opening the bottle? A team of researchers at U.C. Irvine believes they have developed a valuable new tool in the battle against counterfeit wines—a test that authenticates wine by extracting wine vapor molecules from the cork while it's still in the bottle.
Fraud and scandal in the wine business are nothing new, but growing interest in rare collectible wines and the increasingly global nature of the industry has exacerbated the problem. It's unclear how big that problem is, but a report by the International Chamber of Commerce projected that more than $1.77 trillion worth of counterfeit goods will be traded worldwide this year. For wine, that ranges from cunning fakes of rare old Bordeauxs to cheap knockoffs of Australian Shiraz.
Existing fraud-detection measures come with drawbacks. Several tests to determine the vintage of a wine require opening the bottle. Other methods are inexact or require having an authentic sample of the wine on hand to compare the results. Most wine authenticators still work by taking a long look at bottles, labels, corks and capsules for telltale signs of forgery.
Dr. Simon Fahrni and Dr. Benjamin Fuller are researchers in U.C. Irvine's Earth System Science department. They also enjoy wine. Discussing the counterfeiting problem, they began brainstorming a new test and asked Dr. John Southon, director of the university's radiocarbon dating laboratory, for help. "Simon and I set about designing and conducting the necessary experiments in our free time and on the weekends," Fuller told Wine Spectator. "This was a 'fun, what-if project' and not part of our routine research experiments, and we had no idea if we would succeed."
According to their recently published study in Analytical Chemistry, the three men did succeed, creating a noninvasive procedure that uses vacuum suction to date a wine by its angel's share.
Due to the natural permeability of the bark of a cork tree, the ullage—the small headspace between the wine's surface and the cork—grows over time as alcohol and water particles escape as vapors, a loss often called the "angel's share."
The new vintage verification method uses a vacuum to extract gas and liquid vapors, part of the angel's share that has evaporated and is passing through the cork. The vacuum is applied only to the top of the cork, leaving the majority of the closure and bottle unaffected. After the extraction, the cork can then be "bled up" with inert argon gas, protecting the cork and wine from air intrusion.
The extracted gas is analyzed to measure atoms of Carbon-14, a radioactive isotope. Atmospheric levels of Carbon-14 have varied in the last 60 years as a result of aboveground nuclear explosive testing. Each Carbon-14 atom is minute compared to the other particles in the sample size—Fuller compared it to searching for one drop of water in 20 Olympic-size swimming pools. "We're looking for a needle in a haystack," said Fahrni.
After testing 32 wines loaned by a kind wine collector—Fuller's father—the team was able to accurately date 23 of them, or 72 percent. They are working on a portable device, potentially allowing investigators to sample bottles in a cellar before analyzing the results in a lab.
One hundred percent accuracy remains out of reach, however. Some natural corks retain less permeability than others, limiting the sample size, and carbon contamination and corked wines will always add a degree of unpredictability.
The team next plans to test wines that are known to be fraudulent to check the method's reliability. They also believe there are opportunities in measuring other chemicals to possibly sniff out flawed wine. "While a wine might be authentic, is it worth buying if it has spoiled and peaked, or turned to vinegar?" asked Fuller. They hope that what began as a fun project could someday restore wine consumers' confidence.
