Efficacy of Three Light Technologies for Reducing Microbial Populations in Liquid Suspensions

Abstract

The aim of the current study was to evaluate the effectiveness of three nonthermal light technologies (NUV-Vis, continuous UV, and HILP) on their ability to inactivateEscherichia coliK12 andListeria innocua.  E. coliK12 was selected as a representative microorganism for the enterohaemorrhagic foodborne pathogenE. coliO157:H7 andL. innocuaas a surrogate microorganism for the common foodborne pathogenListeria monocytogenes, respectively. The liquid matrix used for the disinfection experiments was a liquid matrix (MRD solution). The results of the present study show that the HILP treatment inactivated bothE. coliandL. innocuamore rapidly and effectively than either continuous UV-C or NUV-vis treatment. With HILP at 2.5 cm from the lamp,E. coliandL. innocuapopulations were reduced by 3.07 and 3.77 log10CFU/mL, respectively, after a 5 sec treatment time, and were shown to be below the limit of detection (<0.22 log10CFU/mL) following 30 sec exposure to HILP (106.2 J/cm2). These studies demonstrate the bactericidal efficacy of alternative nonthermal light technologies and their potential as decontamination strategies in the food industry.