Proactive approach for detecting counterfeit alcohol could save lives

An optical technique developed by researchers at Adelaide University and the University of St Andrews in the UK provides a proactive approach to testing for methanol in alcoholic spirits without having to open the bottle. The researchers are also exploring other applications for the technology, such as combating fraud in the wine and olive oil industry.

Methanol contamination of spirits such as whisky, gin and vodka causes hundreds of deaths each year and can lead to serious physical consequences, such as blindness. Recent high-profile incidents have highlighted the danger: in 2024, six tourists died in Laos after drinking alcohol later found to be contaminated with methanol. It is estimated that methanol poisoning has caused tens of thousands of deaths globally, with incidents documented in nearly 80 countries.

Despite these risks, many current methanol detection methods are time-consuming and reactive in nature. However, the new laser-based method can provide a powerful proactive tool for tackling counterfeit alcohol and improving consumer safety worldwide. This non-destructive screening method allows for the detection of methanol in alcoholic spirits without ever opening the bottle, even when the glass is coloured.

Published in the Journal of Physics: Photonics, the proposed approach is based on Raman spectroscopy, which allows the unique chemical fingerprint of each spirit to be identified. By carefully shaping the laser beam and tuning its wavelength, the team can suppress unwanted signals from the glass bottle and isolate the chemical signature of the liquid inside.

The lead author, Ané Kritzinger from the School of Physics and Astronomy at the University of St Andrews, said: “This work shows that we can look inside a sealed bottle and determine its methanol content, without needing to open it. By carefully shaping the laser light into a ring, and slightly tuning its colour during the measurement, we can isolate the signature of methanol and suppress the signals from both the bottle and the main spirit.

“Crucially, it works across a wide range of real-world bottles, including green, brown and blue glass, where previous methods have struggled. It can be used for both colourless spirits like gin and vodka as well as coloured alcohols like whisky. This allows us to quantify methanol concentrations with a limit of detection of 0.2% — 10 times lower than the human safety limit.”

Dr Graham Bruce from the School of Physics and Astronomy, who co-led the research, said: “This technology opens the door to rapid, non-invasive screening for food and chemical safety, or for fighting the illegal trade in counterfeit spirits, pharmaceuticals or perfumes.”

The work builds on earlier research from the St Andrews group that demonstrated authentication of spirits through clear glass bottles. By overcoming the challenges posed by coloured glass and fluorescence, the new study represents a significant step towards practical, real-world deployment.

As well as improving safety in the beverage industry, the researchers expect the technique to also have wider applications. They are working towards developing a hand-held device that could be used to enable onsite non-destructive quality control and authenticity checks of packaged goods across multiple sectors.

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