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A good year for wine collectors: Carbon dating can accurately determine the vintage

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The most expensive wine ever sold in the U.S. was a Montrachet 1978 from Domaine de la Romanee-Cont, according to a report by Forbes.com. Following a bidding war between two avid collectors, the seven-bottle lot sold for a whopping $167,500 (almost $24,000 per bottle) in a 2001 auction at New York City's Sotheby's.


With rare vintages, like the Montrachet, collecting stratospheric prices, misrepresenting a wine's vintage and wine fraud in general is a major concern. "The problem goes beyond ordinary consumers being overcharged for a bottle of expensive wine of a famous winery with a great year listed on the label," said wine chemist Graham Jones in a prepared statement. "Connoisseurs collect vintage wines and prices have soared with 'investment wines' selling for hundreds of thousands of dollars a case at auction." But how can you find out what year the wine really came from?


That's where two decades of atomic bomb testing can offer clues. Radioactive carbon released into the atmosphere during the blasts and then absorbed by grapes can be used to accurately determine wine vintages, according to a study presented March 21 at the National Meeting of the American Chemical Society. By comparing the level of a radioactive form of carbon (carbon 14) to the level of the more stable and abundant carbon isotope (carbon 12), Jones and his team from the University of Adelaide in Australia were able to determine a what year a wine was really made.


"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," Jones said in a prepared statement. "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 bomb tests stopped in 1963, the clock started ticking as the atmospheric carbon 14 from the "bomb-pulse" was diluted by carbon dioxide generated by the burning of fossil fuels, according to Jones.


The vintage-determining process requires careful examination of the wine using an accelerator mass spectrometer (an expensive device that determines the elemental composition of a sample), so don't expect bottles from the local liquor store to be carbon dated anytime soon. But Jones' method might make some wine-sellers think twice about faking vintages.


Image courtesy of Wikipedia Commons

The views expressed are those of the author and are not necessarily those of Scientific American.

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