Abstract: Ultraviolet C light-emitting diodes (UVC-LEDs) are a new UV light source with various advantages, such as environmental friendliness, high efficiency, and long life span. In the past few years, UVC-LEDs have shown great potentials in the food industry. This work aimed to investigate the inactivation kinetics of foodborne bacteria on the surface of food contact materials by UVC-LEDs and the factors influencing it. The results showed that UVC-LEDs caused higher inactivation of Escherichia coli O157:H7 than Listeria monocytogenes inoculated on food contact materials. The number of L. monocytogenes inoculated on glass, oriented polypropylene (OPP) film, stainless steel, and kraft paper decreased from an initial value of 5.45, 5.56, 5.11, and 5.47 (lg (CFU/cm2)) to 0.60, 0.70, 1.04, and 5.08 (lg (CFU/cm2)), respectively, after UVC-LEDs treatment at 800 mJ/cm2. Similar results were obtained for E. coli O157:H7 inactivation on these food contact materials. Both Weibull model (R2 > 0.922) and Biphasic model (R2 > 0.960) fitted well the inactivation curves of both bacteria. The bactericidal effect of UVC-LEDs against bacteria on glass, OPP film, stainless steel and kraft paper decreased in that order, which might be related to the surface roughness and hydrophilicity of food contact materials. The above results indicate that the antimicrobial effect of UVC-LEDs may be affected by microbial species as well as surface characteristics of food contact materials.

Key words: ultraviolet C light-emitting diodes; microorganisms; inactivation; food contact materials; kinetics