Inactivation efficacy of a sixteen UVC LED module to control foodborne pathogens on selective media and sliced deli meat and spinach surfaces

Abstract

Based on the Minamata convention, prohibiting the use of mercury, UVC LED technology has been researched as a putative replacement for mercury lamps. In this study, the possibility of inactivating Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on selective media and sliced deli meat and spinach surfaces by a simple UVC LED irradiation system was evaluated and inactivation rate constants of the bacteria were analyzed in survival curves with highly accurate modeling equations. The UVC LED irradiation system fulfilled 3 log reductions of E. coli O157:H7 and S.Typhimurium on their corresponding selective media within 1.35 s and 3.60 s, respectively. Log linear and Weibull model equations described the survival of bacteria on selective media very well based on the parameters of goodness of fit kinetic models, and 2-15 mJ/cm(2) D-3d and D-5d values were calculated. Pathogens inoculated onto sliced deli meat and spinach surfaces were reduced by 1.5-3 log reductions within 34 s of UVC LED irradiation. Significant differences in k values were observed in pathogens on selective media (P < 0.05), while relatively similar k values were obtained from food surfaces even though there were significant differences in some points (P < 0.05).