Being palmed off with a young whisky whenexpecting an 18-year-old single malt can be a glass-half-empty moment. But now scientists havedeveloped an "artificial tongue" that might makesuch skulduggery a thing of the past.
The team, based in Scotland, say their device canbe used to tell apart a host of single malts – a movethey say might help in the fight against counterfeit products.
"You could train your particular 'tongue' to know what one of these whiskies 'tasted' like, sothat when the fake stuff came along it could identify it and when the real stuff came along itcould confirm that it was the real stuff," said Dr Alasdair Clark, the lead author of the researchfrom the University of Glasgow.
Clark said the technology could be incorporated into a small, portable device and have a widerange of applications, from identifying poisons to environmental monitoring of rivers.
"Initially we thought of it more for sort of production line, quality control maintenance, [forexample] if you are an apple juice company and you want to make sure that the apple juice youmake on Tuesday is the same as the one that you made last week," said Clark.
Writing in the journal Nanoscale, the team describe how their artificial tongue is based on aglass wafer featuring three separate arrays, each composed of 2 million tiny "artificial tastebuds" – squares about 500 times smaller than a human taste bud, with sides just 100nm long.
There are six different types of these squares in the device, three types made from gold andthree from aluminium. Each of the three arrays contain one type of gold and one type ofaluminium square.
When light is shone on an array, it interacts with the electrons at the surface of the squares, resulting in dips in the reflected light which can be measured. These dips appear at slightlydifferent wavelengths depending on which type of square the light interacts with.
Crucially, these dips shift depending on the liquid surrounding the arrays. The upshot is thateach liquid gives rise to its own "fingerprint" of measurements. That means the device canbe used to tell apart different liquids – and even identify them if they have been recordedbefore – without revealing their makeup, rather like our own tongues do.
"Your tongue can't tell you what is in black coffee, but it knows what black coffee tastes like," said Clark.
While this "artificial tongue" is not the first to be made, the team say its arrangement ofartificial tastebuds is a step up from previous approaches, making the device smaller andspeeding up information gathering.
To test their device, the team covered their "artificial tongue" in seven different single maltwhiskies in turn, as well as water, 40% vodka, and ethanol in water.
The team found that the device produced a different pattern, or fingerprint, of results foreach of the whiskies, allowing them to tell apart a range of drams including 12- and 18-year-old samples of Glenfiddich, 10-year-old Laphroaig and Glen Marnoch's single malt Rum Cask. The team suggest this is due to tiny differences in the presence of various components – aromatic chemicals produced plants such as vanillin and terpenes.
"Although [the whiskies'] chemical compositions are pretty similar, the way that we havedesigned the experiment means that we can still separate them out as separate entities," saidClark.