wine, wine glass
AP Photo/Fernando Bustamante

How Do You Spot Vintage Wine? It Has Fewer Radioactive Particles

January 22, 2011 07:00 AM
by Haley A. Lovett
The level of radioactive carbon in wines made after 1950 is higher due to nuclear bomb testing, making it easy to identify new wine posing as century-old vintage.

Atomic Bombs, a Bane to Counterfeit Winemakers

At a meeting of the American Chemical Society in San Francisco, Graham Jones of Australia’s University of Adelaide presented research showing he could prove the authenticity of a vintage through carbon dating.

“Carbon dating works by comparing the amount of carbon 14, which is a less common and less stable form of carbon, to the more abundant carbon 12.” The ratio between these two forms of carbon held consistent for thousands of years, but was altered by two decades of atomic bomb testing after World War II, which increased the amount of radioactive carbon 14 in the atmosphere. The grapes used in wines made after this period absorb carbon dioxide and “take in trace amounts of the heavier carbon isotope—which eventually show up in the wine.” So when a so-called “vintage” is found to have elevated levels of carbon 14, it’s a dead giveaway.

Carbon dating is already widely used to expose counterfeit vintage whiskey.

Radiocarbon Dating Helps Identify Counterfeit Whiskey

A bottle of whiskey masquerading as an 1856 Macallan Rare Reserve, which could have sold for tens of thousands of dollars, had to be withdrawn from a Christie’s auction because its origin was determined as being sometime after 1950. A surprising characteristic revealed the true age of the malt: radioactive particles.

Researchers at the Oxford Radiocarbon Accelerator Unit are now able to tell if a whiskey was made prior to 1950, thanks in part to the nuclear testing going on at that time. Organic material living after the start of nuclear testing contains more traces of radioactive carbon than organic material from before the time of nuclear testing. Barley, which is used to make whiskey, is organic material, and thus scientists can examine whiskey for trace amounts of radioactive carbon and determine when it was made.

The majority of the testing is done for the Scotch Whisky Research Institute, a scientific center that aims to maintain distilled beverage quality, improve distilled beverage manufacturing and preserve the integrity of the industry by authenticating products (such as vintage whiskey).

Dr. Tom Higham, deputy director of the Oxford Radiocarbon Accelerator Unit, says that the majority of the whiskey samples sent to them end up turning out to be from after the 1950s. Although the radiocarbon dating has helped identify cases of counterfeiting a vintage bottle of whiskey, it can’t always identify the exact date of creation.

Background: How radiocarbon dating works with whiskey

Carbon 14 is a radioactive particle found naturally in the atmosphere as carbon dioxide. Plants absorb the radiocarbon through photosynthesis, and animals then absorb the radiocarbon when they eat plants. The levels of radiocarbon found in plants or animals would then be the same as those found in the atmosphere during its lifetime. After the plant or animal dies, the radiocarbon begins to decay; scientists use the ratio of radiocarbon to stable carbon found in the organism’s remains, along with their knowledge of the rate at which radiocarbon decays, to put an age on the remains.

Although all organic material collects a certain amount of carbon 14 during its lifetime, elevated levels of radioactive carbon present after nuclear bomb testing started in the 1950s makes it so that plants and animals from after that time contain an elevated level of the carbon. This artificial elevation of the radiocarbon is what gives away a counterfeit whiskey posing as a century-old variety.

When the lab gets a sample to test, they burn the whiskey and use electricity to charge the resulting gas from the burn, and measure the amount of carbon 14 present.

Before the researchers at the ORAU began to authenticate whiskey for buyers and sellers, the Scotch Whisky Research Institute sent them samples of whiskey with already-known dates of creation to ensure that the method worked. The ORAU was able to properly identify the samples provided, and even discovered that one sample had been improperly labeled. Due to its success in authenticating whiskey using radiocarbon dating, the lab started dating wines, although wine dating can be more difficult because of the variety of organic material used to make it.

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