Australians take advantage of nuclear fallout
Brits and French prefer to shoot ion beams from particle accelerator
Update 17:35 Australian researchers have succeeded, after 11 years of research and several hundred bottles of wine, in coming up with a new carbon-dating method to check the real age of vintage wines. It’s not cheap, but the team that did the research at the University of Adelaide says fraud accounts for about five percent of all expensive vintage wines, and with auctions pushing up the prices to nearly undrinkabe levels, investors want to be sure they are not buying fakes.
One of the researchers, Graham Jones, reported the team’s findings at the American Chemical Society’s annual meeting in California Saturday 21 March.
Jones and his colleagues found that radioactive carbon dioxide produced from atomic bomb tests in the atmosphere absorbed by grapes can be used to accurately determine wine vintages. “The new technique is similar to radio-carbon dating, used for years to estimate the age of prehistoric objects.
“It works by comparing the amount of carbon-14 (C-14), a less common form of atmospheric carbon, to carbon-12 (C-12), which is more stable and abundant. The ratio of these two carbon forms, or isotopes, has remained constant in the atmosphere for thousands of years,” says the ACS in its press release.
C-12 and C-14 are, captured by grapevines when they absorb .
Jones told GenevaLunch that “the thrust behind the method is that it is different to carbon dating which relies upon radioactive decay of 14C. The bomb pulse method uses dilution of 14C and is much more accurate for the peroid specified.”
Jones told the ACS meeting that “until the late 1940s all carbon-14 in the Earth’s biosphere was produced by the interaction between cosmic rays and nitrogen in the upper atmosphere. This changed in the late 1940s, up to 1963 when atmospheric atomic explosions significantly increased the amount of C-14 in the atmosphere. When the tests stopped in 1963 a clock was set ticking – that of the dilution of this ‘bomb-pulse’ C-14 by CO2 formed by the burning of fossil fuels.”
He explains that traces of radioactive carbon are captured by the grape plants through the absorption of carbon dioxide and eventually transformed into alcohol and other carbon-based components of the wine. The “bomb-pulse” of the atmosphere is eventually absorbed into the wine.
“The year that the grapes were grown fixes the age or vintage of the wine,” Jones says. “The carbon-14 isotope ratio of the wine alcohol can therefore be used to determine the vintage of a wine.”
The researchers used an accelerator mass spectrometer to determine the C-14 levels in the alcohol components of 20 Australian red wines with vintages from 1958 to 1997. They then compared these measurements to the radioactivity levels of known atmospheric samples. They found that the method could reliably determine the vintage of wines to within the vintage year.
Jones argues that measuring the age of other wine components such as tartaric acid and some phenolic substances can help improve the reliability of the technique to detect fraud.
“Wine also is a reservoir of environmental data which will complement the results from trees,” the team said in 1999, when they began their research project. The initial results were publishedin 2004.
The university of Adelaide noted in a 1999 press release that “The scientists plan to extract that data from vintage wine series supplied by some of Australia’s leading producers.”
A tough job – all in the interest of science, of course.
The particle accelerator solution
Meanwhile a British firm, the Antique Wine Company in London, which specializes in costly vintage wines, teamed up in 2008 with the National Centre for Scientific Research in Bordeaux, France to develop a fraud-detection system that shoots ion beams from a particle accelerator, comparing the bottle tested with a baseline of wines from the same producer.
The business of wine authentication (updated November 2018) is clearly taking a scientific turn, which the particle accelerator specialists at Cern in Geneva might like to explore with nearby wine producers in France and Switzerland. Fortunately for those of us limited to checking the quality of our wines by tasting them, no one is yet turning up his nose at this traditional approach.