Article about a special spectroscopy technology, known as ‘Raman’, which offers a rapid and non-destructive method to detect fraudulent food items among authentic ones. Written on behalf of the NUS Forensic Science Group.

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Ever eaten something you thought tasted slightly peculiar from how you remembered it to be?

You might just be a victim of food fraud — the criminal tampering with food for financial gain. Committed through substitution, contamination or dilution of the food product, food fraud compromises the safety and quality of the edibles you consume. Moreover, advancements in food technology have also made it more sophisticated and better at eluding detection.

To tackle this problem, collaborators from the Forensic Science Research Lab and Department of Food Science and Technology of National University of Singapore (NUS), and the Disruptive & Sustainable Technologies for Agricultural Precision research group of the Singapore-MIT Alliance for Research and Technology (DiSTAP SMART) have successfully adapted Raman spectroscopy for identifying counterfeit food products accurately, rapidly and with the food undamaged.

“Raman spectroscopy has many applications, from clinical to industrial uses” said Associate Professor Stella Tan, the principal investigator of the Forensic Science Research Lab, “Using it to chemically characterise and detect fake food is something the NUS Forensic Lab and the MIT Group are both interested in.”

This is a marked improvement from current methods of detection, which require a much longer time and, ultimately, the breakdown of food. Hence, one of its greatest significance is for law enforcement, since this system not only exposes fraud, but it also allows for the food in question to be preserved as evidence.

How Raman spectroscopy works is by detecting scattered light. When light is casted on a compound, its molecules can absorb and re-emit the light in various directions, thus ‘scattering’ it. When the scattered light exhibits a longer or shorter wavelength than the source, it is known as ‘Raman scattering’. Since each molecule has its own unique pattern of scattering, or a ‘chemical fingerprint’, we can identify the chemical composition of a compound by distinguishing its patterns of scattering, which show up as peaks on the graph.

How Raman scattering works and how it shows up in a spectrum. Credit: Tay Shu Chian, NUS.

To test its capabilities, the researchers applied Raman spectroscopy on three food products which are commonly embroiled in food scandals, to test if the system is robust enough to differentiate between authentic and tampered food. They included salmon (which is commonly substituted with trout), milk powder (which may contain contaminants) and alcohol (which may contain a lower concentration of ethanol than stipulated).