A study carried out by scientists, has revealed promising results with LEDs showing an ability to kill strains of salmonella bacteria in unpasteurised orange juice. Meaning that in the future, fruit-juice dispensers could be fitted with blue light emitting diodes (LEDs) to stave off the salmonella bacteria that makes people ill.
Heading the team of scientists that did the study was Assistant Professor Yuk Hyun-Gyun and his former PhD student, Dr Vinayak Ghate.
Researchers used LEDs of wavelength 460 nanometers to illuminate orange juice that was artificially contaminated with five strains of salmonella. It was then observed that the lights could kill off almost all the salmonella cells. When the bacteria absorbs the blue LEDs, it sets off a process where free radicals are produced to break down the bacterial cells, explained Prof Yuk.
"It took about four to 11 hours to kill 99.9 per cent of salmonella in the orange juice at different temperatures," said Prof Yuk, who added that a longer time was needed to kill the bacteria under conditions which were below room temperature. "Right now there is no other technology that can kill off the bacteria in juice dispensers. Refrigeration merely prevents the bacteria from growing."
The study findings were published in April this year in the Journal Of Food Protection.
But while the approach of using blue LEDs is interesting, Professor William Chen, director of Nanyang Technological University's Food Science and Technology Programme, said that further investigations would be needed to see if it can be adopted on a commercial scale. "Currently, most fruit juices are pasteurised (short-time heating at high temperature to inactivate bacteria and other pathogens) before reaching retail shelves, and the proportion of unpasteurised juice remains relatively small," he added.
