Near-infrared analysis method detects counterfeit whisky

Working on a method to detect counterfeit whisky, a team from the university’s school of physics and astronomy has devised a device that can achieve this and pinpoint exactly which whisky the sample was from.

Counterfeit branded single-malt whiskies are a major problem for the whisky industry.

The St Andrews researchers, led by Prof Kishan Dholakia, use laser-based near-infrared spectroscopy to analyse samples — generally biological — using a microfluidic device that guides the laser into the sample through an optical fibre.

Another fibre collects light scattered from the sample and takes it to an analyser.

The original goal of the research was to determine the alcohol content of the sample, which is a key indicator of whether the whisky is fake.

The advantage of the microfluidic method is that it can obtain very accurate results, within one per cent, from a sample of only 20µl in around two seconds.

However, the team found that the technique also detects other compounds within the whisky, resulting from the brewing process and the maturation of the spirit in wooden casks. Although these only make up one per cent of the volume of the whisky, they have a very large influence on the taste, colour and texture of the drink.

When analysed by the laser, these compounds create a ‘fluorescence background’ that changes the shape of the peaks corresponding to the alcohol in the whisky’s spectrum.

This, the researchers found, can identify the brand of whisky; how long the spirit has been maturing; and even the type of cask it was maturing in. ‘This could be used to check for counterfeit whiskies, and also by the distilleries, for quality control; they can use a sample as a benchmark to compare their other whiskies against,’ researcher Paveen Ashok told The Engineer.

‘It’s amazing that the technology we are developing for biomedical analysis can also be used to help us enjoy a wee dram,’ said Prof Dholakia. ‘And with a minimum of waste.’