Study shows that blue LEDs kill foodborne pathogens in fresh-cut food

September 21, 2015

Lethal LightA group of scientists from the National University of Singapore (NUS) recently discovered that blue light emitting diodes (LEDs) have a strong antibacterial effect on three major foodborne pathogens. Exposure to illumination from blue LED light can start the process within cells that ultimately those cause cells to die. This opens possibilities as a chemical-free option for food preservation.

The team tested the light’s effects on pathogens Listeria monocytogenes, E. coli and Salmonella typhimurium under temperature and pH conditions associated with storage of food products. Assistant professor Yuk Hyun-Gyun, who led the team, said that they tested the lights on fresh-cut fruits, such as papaya and mango, as well as on orange juice.

“It is too early to say the results because the results are not published yet,” he said. “According to our preliminary study, though, the illumination of blue LEDs effectively kills (more than 90 percent of population) salmonella cells on fresh-cut fruits at chilling temperatures.”

However, Hyun-Gyun notes that at ambient temperatures, blue LEDs only retard the growth of bacteria on the surface. However, in orange juice, blue LED with an irradiance of 92 mW/cm2 killed more than 99.9 percent of the population of salmonella at chilling temperatures within a couple of hours.

“Other studies have shown the potential of blue LEDs as novel food processing technology with the aid of natural photosensitizers,” Hyun-Gyun said. “Thus, blue LEDs can be used in the food industry not only for food preservation but also food processing.”

The team continues testing the antibacterial effect of blue LEDs (405 and 460 nm) with fresh-cut fruits. In addition, they have also tested the effects of other LEDs – blue, green and red – on physiochemical and nutritional quality changes of spinach and lettuce.

“We hope these studies help us to evaluate various potentials of LEDs for agriculture and food industries,” Hyun-Gyun said.

— Melanie Epp, contributing writer