A few years ago, a Chinese millionaire visited a Swiss hotel and plopped down $10,000 for a single dram of Scotch whisky. The Scotch in question was from an unopened bottle of 1878 Macallan single malt. It was, at the time, the highest price ever paid for a single serving of whisky. The full bottle was valued at $330,000.
Only there was a problem. The whisky was a fake. After opening it, the hotel sent out a sample to a specialist group that carried out carbon dating analysis. Their conclusion was that there was a 95% probability that the whisky was distilled not in 1878 but, instead, sometime between 1970 and 1972.
Such fakes are, it turns out, surprisingly common. Research carried out in 2018 concluded that 21 out of 55 rare bottles of Scotch acquired from leading auction houses were either fake or not distilled in the year claimed. With so much money on the table (or, rather, in the glass), why wouldn’t such forgeries be a common occurrence?
But researchers from the University of St. Andrews in the U.K. have come up with a way to quickly test whiskies for authenticity. And, like the best tests, it involves lasers.
Laser spectroscopy to the rescue
“Our group, over the last decade, has been developing techniques that use lasers to verify the authenticity of whisky,” Graham Bruce, Senior Research Laboratory Manager in the Optical Manipulation Group at the University of St. Andrews, told Digital Trends. “We have methods that work and that can identify what kind of whisky you have. But to use them, you need to take the whisky out of the bottle because the method also picks up a signal from the glass. That signal can often be stronger than the signal from the content.”
The problem with this approach is that, in order to validate that a rare sealed bottle of whisky is as described on the label, you have to unseal it — thereby destroying a large part of its value. “The real breakthrough is that we’ve [now found a way to] carefully shape our laser beam so that it focuses down inside the bottle,” Bruce continued. “[As a result], we get a strong signal coming from the whisky, while the signal from the glass is essentially zero. It means you can apply this method to a valuable drink that you don’t want to open.”
The laser spectroscopy method pioneered by the team involves shining a laser light into a substance of interest (in this case, Scotch) and then observing the way the light scatters as it interacts with the sample’s molecules. The colors of the scattered light vary according to the chemical makeup of the whisky. Using a multivariate data analysis tool, the team is then able to analyze the scattered light to reveal details like distillery, age, and other features that act as identifiers for comparing the whisky with another of its kind.
Bruce acknowledged that, in the case of particularly rare whiskies, it might be harder to gain the validation data since you need a proven authentic whisky to compare against. (However, analysis could still be useful for revealing details about the age or origin of particular whiskies to weed out fakes.) But going forward, this concept could prove to be very valuable.
“One way that we see this working in the future is that you have the device in distilleries or bottling plants, and you test the liquor at that point,” he said. “Then you store the information, like taking the fingerprint of the liquor. Then, whenever the liquor appears again, you can take its fingerprint and those fingerprints should match [what you have on record.] Or should, at least, evolve in a way that we can predict.”
Not just for the fat cat billionaires
Of course, most of us won’t be dropping $10,000 on a shot of whisky. (At least, not until the economy picks up a bit!) However, Bruce said this could still prove to be a very useful tool.
“There are deaths all around the world from counterfeit alcohol every year,” he said. “In places like Russia, the Czech Republic, the Dominican Republic, all over the world you hear about cases where people are dying because they get something in an original glass bottle from a whisky manufacturer, which [turns out to] not be whisky. Maybe it has methanol or something like that in it, which is poisonous or causes blindness.”
There is, he said, a full spectrum of use-cases, “right from the very cheap whisky being sold to people without significant economic means all the way through to the high-end stuff being bought by the fat cat billionaires.”
A paper describing the work, titled “Through-bottle whisky sensing and classification using Raman spectroscopy in an axicon-based backscattering configuration,” was recently published in the journal Analytical Methods.