Blue LED preserves food

18 August 2015 | Research
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Dr Yuk (centre), with PhD students Vinayak Ghate (right) and Kim Min Jeong, holding LED light boxes used in their research (Photo: The Straits Times ?? Singapore Press Holdings Ltd)

Besides being energy savers, blue light emitting diodes (LEDs) may soon help to keep consumers safe from food poisoning.

NUS researchers at the Food Science and Technology Programme in the Faculty of Science have shed light on the pathogen-killing property of blue LED. Experiments on bacteria such as Salmonella and Escherichia coli, major culprits of food poisoning, showed that the light-sensitive compounds of these microorganisms make them vulnerable to the shorter wavelengths of the blue LED.

The scientists found that the neutralising effect is most potent at low temperatures of between 4°C and 15°C, in slightly acidic conditions. The work led by Assistant Professor Yuk Hyun-Gyun is the first to demonstrate that temperature and acidity affect the antibacterial efficacy of LED.

Asst Prof Yuk pointed out that chilling acidic foods, coupled with blue LEDs, could "meet the increasing demand for natural or minimally processed foods without relying on chemicals such as acidifying agents and artificial preservatives.

The discovery, published in Food Microbiology in June, could well eliminate chemicals from the equation of processing and preserving food. The next step for the researchers is to employ the LED approach to fresh-cut fruits, ready-to-eat seafood such as sushi and salmon, as well as chilled meat products, he said.

The investigators plan to verify if LED illumination can effectively kill pathogenic bacteria without deterioration of food products. If successful, the new method will be a boon for retail settings, hawker centres, food courts, supermarkets and food suppliers.

The team has been collaborating with Agri-Food & Veterinary Authority (AVA) of Singapore to apply the new technology to fresh-cut vegetables to determine if LEDs will improve their nutritional quality during storage. Key parameters examined include vitamins and chlorophyll.

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Blue LEDs pathogen-killing effect is most effective in slightly acidic and low-temperature conditions