Laser Technique Detects Fake Alcohol Without Opening the Bottle

Scientists from the University of St Andrews in Scotland and Adelaide University in South Australia have developed a way to detect methanol in alcoholic drinks without opening the bottle, using a laser-based technique called Raman spectroscopy. Methanol poisoning from counterfeit alcohol is rare in strictly regulated countries but remains a serious problem elsewhere; a 2025 outbreak in Turkey killed 160 people and left more than 250 others incapacitated, and just 10 millilitres of methanol -- about two teaspoons -- can cause permanent blindness and kidney failure.

Counterfeit producers sometimes dilute drinkable ethanol with methanol, an industrial chemical used in products such as windshield-washer fluid and antifreeze, because it mimics a higher alcohol content, is cheaper, and is not taxed the way drinkable alcohol is. Raman spectroscopy works by directing a laser beam into a liquid and analysing how the light scatters as it excites the liquid's molecules, producing a distinctive pattern that reveals its chemical composition. By carefully shaping the laser beam and changing its wavelength, the researchers were able to filter out interference from the bottle itself, meaning the liquid can be tested without opening it.

The team detected methanol in whiskey at concentrations around 10 times lower than internationally recognised safety standards, and the method is cheaper and faster than traditional laboratory testing. The researchers say it could also be used to identify counterfeit perfumes and detect pesticide contamination in olive oil, offering broader quality control across agriculture and food safety.

The technology is primarily aimed at customs agencies, alcohol producers and distributors, and food safety authorities rather than individual shoppers, and consumers remain vulnerable to fake alcohol reaching store shelves. Avoiding suspiciously cheap alcohol and poorly labelled products remains a sensible precaution, the researchers said.