How do you know if a wine is the real thing? It’s an issue that has cost some fine-wine collectors millions of dollars and seen the counterfeiters jailed.
While experts try to sort the genuine from the fakes using their eyes, nose and mouth, there may be an alternative solution. A machine that can analyze the origin of a wine through its water content has been used to create a database of wine isotopes over the past 20 years in Europe. But the cost has been prohibitive. Until now...
Isotope analysis is brought into play to authenticate foodstuffs by verifying whether products like wine, fruit juices and honey have been adulterated by the illegal addition of water and/or sugar additions.
In technical terms, isotopes are variants of chemical elements such as carbon, oxygen or hydrogen. All isotopes of an element share the same number of protons, but they differ in neutrons. The number of neutrons plus the protons makes up the isotope number.
For example, there are three natural isotopes of carbon: carbon-12, carbon-13 and carbon-14. Every carbon atom has 6 protons, so the neutron numbers of these isotopes are 6, 7 and 8.
Isotope measurements have been widely adopted in the European Union since it decided to create a databank for all wine-producing member states in 1990. These are used to check for chaptalization, the addition of water, and sweetening with sugar, and can also authenticate geographical origin and the vintage.
But beyond Europe, isotope analysis has been used sparingly on wines because it is both time consuming and expensive to undertake, explains Manish Gupta, chief technology officer at Los Gatos Research in California.
“People are using mass spectrometry [for isotope analysis] all over the world for wines. But the machines are very complicated to use and very expensive: they can cost as much as $200,000 per instrument,” he says.
Gupta's team has worked on a new – and cheaper – method of measuring isotopes with lasers. It involves taking a micro-liter [1/1000 of a milliliter] of wine and evaporating it to become a gas before passing a laser through the gas. ”All we are looking at is the water, the different isotopes of water," Gupta explains. "All isotopes absorb the laser at slightly different wavelengths. You can measure the optical absorption of the water in the wines and quantify the different isotopes.”
And the cost of the machine is around $45,000. “The novelty here of laser-based methods is that we make them smaller and cheaper so people can do a lot more of these analyses a lot more quickly. The instruments can be run by untrained users – we often have a student running them so you don't have to have an expert using it.”
While these laser-based methods can be used to verify the contents of the bottle, how detailed is the analysis? Could a Vosne Romanée village level wine be distinguished from a Romanée Conti grand cru? That's unlikely, says Jason West, an assistant professor at Texas A&M University, who co-authored a 2007 study on wine isotope ratios.
“The water sources and climate in such a small area would be expected to be similar and so the wine oxygen isotope ratios of two wines from the same village would be expected to be similar as well," says West. "Other tools would have to be applied to such a case.”
Those tools do exist. According to a 2009 study published by Innovative Romanian Food Biotechnology, other methods – including measuring the volatile compounds in a wine – have been shown to distinguish between wines produced in different countries. In addition, amino acid profiling in a lab has been used to differentiate between wines from Burgundy, Bordeaux and Beaujolais, as well as to establish the authenticity of wines from Portugal’s Douro Valley and Italy’s Campania. An analysis of the mineral composition of wines is also a procedure for assessing geographical origin. The authors of the Romanian study conclude that several different tests are necessary to prove authenticity: the isotope method is not sufficient on its own.
The other issue with isotope analysis is that a bottle has to be opened when the essential micro-liter of wine is drawn off for testing, which makes things a bit tricky when it comes to fine wines. Initially, this technique was used for “large, bulk export/import kind of issues, and secondary markets and emerging markets like China where we're seeing a lot of fraudulently activity,” says Gupta. However, the method may also have a future in fine-wine authentication. If the recently launched Coravin device lives up to its claim of being able to extract a drop without compromising the wine inside the bottle, it could be used in conjunction with isotope testing.
“The Holy Grail is that you'd be able to look at a wine and say, 'This is from this vineyard, so I should know its isotope ratio," concludes Gupta. Until then, tackling wine fraud will need to lean on the traditional trifecta of sight, smell and taste, along with a variety of existing technologies.