Efficacy of ultraviolet light (UV-C) and pulsed light (PL) for the microbiological decontamination of raw salmon (Salmo salar) and food contact surface materials. (December 2018) - Pedrós-Garrido, S.
Abstract: The decontamination effect of two light-based technologies on salmon, polyethylene (PE) and stainless steel (SS) was evaluated. Optimization of treatment conditions for ultraviolet light (UV-C) and pulsed light (PL) was carried out on raw salmon, obtaining inactivation levels of 0.9 and 1.3 log CFU/g respectively. The effects of treatments on several microbial groups present in salmon were then evaluated. For both technologies, Pseudomonas spp. were found to be the most resistant group of microorganisms tested. Three different strains from within this group were isolated and speciated, including a P. fluorescens strain which was selected for subsequent studies. PE and SS surfaces were inoculated with a suspension of the P. fluorescens suspended in a 'salmon juice' solution, and treated with UV-C and PL at different doses (mJ/cm 2 ). PE surfaces were effectively decontaminated a low doses for both technologies, with a reduction of >4 log cycles observed. Decontamination of SS was also effective when treated with PL, although at higher doses than for PE. When SS was treated with UV-C, the maximum reduction of P. fluorescens achieved was 2 log cycles, even at the highest dose. Highlights: UV-C and PL treatment doses were dependant on the treatment time and the distance from the light source Optimal treatment for salmon decontamination was between ~130–150 mJ/cm 2 for both technologies Pseudomonas spp. were the most resistant bacterial group to UV-C and PL treatments on salmon Pseudomonas fluorescens inoculated on polyethylene surfaces was effectively decontaminated with low does of UV-C and PL P.fluorescens inoculated on stainless steel surfaces was effectively decontaminated with PL (for UV-C max. 2 log cycles)