Application of the 222 nm krypton-chlorine excilamp and 280 nm UVC light-emitting diode for the inactivation of Listeria monocytogenes and Salmonella Typhimurium in water with various turbidities

Abstract

Applicability of the 222 nm krypton-chlorine (KrCl) excilamp and 280 nm UVC light-emitting diode (LED-UVC) for water disinfection was identified in this study. Listeria monocytogenes and Salmonella Typhimurium were inactivated by the KrCl excilamp and LED-UVC treatments in water samples with varying turbidities. Inactivation curves were analyzed using the log linear model, and the derived inactivation rate constant (k) was approached as a function of turbidity using the exponential one-phase decay model. The integrated inactivation model was verified with turbidities other than those used at the experimental levels. Water disinfection efficacy by both the KrCl excilamp and LED-UVC treatments decreased with increasing turbidity, and the developed model predicted well the inactivation levels of both pathogens depending on the type treatment device, treatment dose, and sample turbidity. When applied to oyster or flatfish spindled samples, the LED-UVC showed higher pathogen inactivation efficacy in flatfish than oysters, as expected due to the lower turbidity of the flatfish spindled samples, but opposite results were observed with the KrCl excilamp. This result indicates that factors other than turbidity such as type of food and pathogen also should be considered. In this regard, further study is needed to identify the bactericidal mechanisms of these alternative UV-C irradiation technologies in water and food products.