Blue LED can kill germs

23 Nov 2014 NUS food scientists discovered a novel technology using blue LED to kill major deadly bacteria commonly associated with foodborne disease.

Refrigeration has been widely used for food preservation because most microorganisms cannot grow at low temperature. However pathogenic bacteria can survive on foods during storage at refrigerated temperature, which could probably cause food poisoning. To solve this problem, Prof YUK Hyun-Gyun and his students from the Food Science and Technology Programme in NUS tested the antibacterial effect of blue (461 nm), green (521 nm) and red (642 nm) LEDs on four foodborne pathogens including Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes and Staphylococcus aureus.

The team has discovered that the blue LEDs have a strong antibacterial effect against these major foodborne pathogens. While the blue LEDs killed 99.99 – 99.999% of germs in bacterial media within 8 hours, the green LEDs killed only 90 – 99% with the same dosage. The red LEDs did not produce any antibacterial effect. The antibacterial effect of LEDs was also observed to be temperature dependent, as this antibacterial effect was more pronounced at cooler temperatures than room temperature (see Figure).

This study suggests the potential of blue LEDs in combination with chilling to be used as a novel food preservation technology, ensuring food safety. This research has been conducted by the collaboration with Agri-Food and Veterinary Authority of Singapore (AVA).

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This figure shows the cross sectional diagram of the LED illumination system and the photograph of LED illumination set-up. [Image credit: YUK Hyun-Gyun]

Reference

Ghate VS, Ng KS, Zhou W, Yang H, Khoo GH, Yoon WB, Yuk HG. “Antibacterial effect of light emitting diodes of visible wavelengths on selected foodborne pathogens at different illumination temperatures.” International Journal of Food Microbiology. 166 (2013) 399.