The synergistic effects of slightly acidic electrolyzed water and UV-C light on the inactivation of Salmonella enteritidis on contaminated eggshells

Salmonella enteritidis (S. enteritidis) infection has been recognized as one of the most common bacterial causes of human gastroenteritis worldwide and is closely associated with eggs. Slightly acidic electrolyzed water (SAEW) is an emerging environmentally friendly technology for disinfecting eggshell surfaces to remove dirt and pathogenic microorganisms. However, the efficiency of SAEW could be affected by the presence of manure. UV-based advanced oxidation processes have been studied to improve the microorganism's inactivation effect of disinfection. Therefore, in this study, the synergistic bactericidal efficacy of SAEW and UV-C light (ultraviolet lamp, λ = 254 nm) for inactivation of S. enteritidis on artificially inoculated eggshells with or without manure was evaluated, and the bactericidal efficacy of different combination treatments of SAEW and UV-C light was compared. Without manure interference, complete inactivation (reduction of 6.54 log₁₀ CFU/g) of S. enteritidis on the surface of eggshells was achieved following a 4-min treatment with SAEW+UV at an available chlorine concentration (ACC) of 20 mg/L. In the presence of manure, a 3.02 log reduction was achieved following a 4-min treatment with SAEW+UV at an ACC of 30 mg/L. Simultaneous treatment with SAEW and UV light exhibits higher bactericidal activity for eggshells than other combination process methods with UV and SAEW. The results suggest that the combined treatment of SAEW+UV is a novel method to enhance the microbial safety of eggshells.