The strong antibacterial effect of blue light emitting diodes (LED) on major foodborne pathogens could lead the way to chemical-free food preservation.
Acidic fruits and ready-to-eat meat can be preserved with blue LED when combined with cold temperatures between 4C and 15C, and mildly acidic conditions of approximately 4.5 pH, without receiving further chemical treatments commonly used in food preservation.
While LEDs are known as an energy-saving light source, bacteria are also sensitive to light in the 400-430 nanometer spectrum known as blue light. Recent research conducted at the National University of Singapore has found that exposing bacteria to illumination from blue LED starts a process within the cell that leads to death.
In the study, three major food-borne pathogens — Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella typhimurium — were tested under blue LED illumination and various pH conditions from alkaline to acidic. Results show that acidic conditions were more effective for L. monocytogenes while alkaline conditions were most effective on E. coli O157:H7 and S. typhimurium, although acidic conditions were also able to deactivate them.
Further testing of the LED technology will involve ready-to-eat seafood and meat products as well as fresh-cut fruits.