Washington, March 22 (ANI): In a new research, scientists have found that radioactive carbon dioxide (CO2) produced from atomic bomb tests in the atmosphere absorbed by grapes can be used to accurately determine if wine vintages are fake or not.
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.
"Until the late 1940's all carbon-14 in the Earth's biosphere was produced by the interaction between cosmic rays and nitrogen in the upper atmosphere," Jones said.
"This changed in the late 1940's 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 added.
He explained 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 said.
"The carbon-14 isotope ratio of the wine alcohol can therefore be used to determine the vintage of a wine," he added.
The scientists used a highly-sensitive analytical device called 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 and 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.
In addition to testing alcohol, measuring the age of other wine components, such as tartaric acid and various phenolic substances, can help improve the reliability of the technique for etecting fraud, according to Jones. (ANI)
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