Radioactive carbon released into the atmosphere during the blasts is being absorbed by grapes. By comparing the level of a radioactive form of carbon, C-14 to the level of the more stable and abundant carbon isotope C-12, the team from the University of Adelaide in Australia was able to determine in what year a wine was really made. The study was presented on March 21 at the National Meeting of the American Chemical Society and has been widely reported as it can help spot fake wines which, estimated at around 5% , are a cause of concern to wine producers, drinkers and investors alike.
Also of concern is the misrepresentation of vintage even by a year as wines from several regions have a significant difference in price from one vintage to the other, especially in Bordeaux and Burgundy. For example Pomerol was a declared disaster in 1991, but extraordinary in 1990. It is no surprise that La Conseillante Pomerol, 1991 sells for $112 while the 1990 vintage fetches almost 3 times at $300.
‘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 bomb tests stopped in 1963, the clock started ticking as the atmospheric carbon-14 from the bomb-pulse was diluted every year,’ according to a statement by Graham Jones, lead author of the study.
Scientists have been able to pinpoint the wine vintage to within a year by analyzing the levels of radioactive carbon in the wine; a technique they say could help detect fraudulent attempts to repackage plonk as a more expensive wine. It is suggested that the recent case of Gallo being conned by the French producers could have been avoided if this technique had been already available.
The scientists analyzed 20 Australian red wines with vintages varying from 1958 to 1997 and compared their levels of radioactivity with calibrated sources of radiation. Using the technique they were able to find out the correct vintage within a year. (So the mystery of spotting La Conseillante Pomerol 1990 and 1991 might still not have been resolved!).
It is important for researchers and reporters to emphasize with a degree of confidence that the amounts of radioactive carbon found in wines made from grapes are harmless. 95% of wines consumed are drunk young, by people who are not really concerned about fake wine. They would be concerned with the presence of nuclear residue in grapes and would need to be reassured that the amounts are too small and harmless and are presence in several forms of daily food that we eat. |