Inactivation of foodborne pathogenic bacteria in water and stainless steel surfaces by vacuum-UV amalgam lamp and low-pressure mercury UV lamp irradiation

The objective of this study was to investigate the inactivation mechanism of a vacuum-ultraviolet (VUV)-amalgam lamp and its bactericidal efficacy on a stainless-steel surface and water compared with that of a conventional low-pressure mercury ultraviolet (LP) lamp. When treated with the VUV-amalgam and LP lamp over distilled water, initial 6-7 log CFU/mL of the foodborne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes) were inactivated over 4.5 log after 60 mJ/cm2 treatment. However, there was no significant difference (p > 0.05) from the action of the VUV-amalgam lamp and conventional LP lamp at the same dose. However, on the stainless steel surface, the VUV-amalgam lamp treatment showed over 1.5 log higher inactivation capacity against the three pathogens at the same 254 nm dose irradiation of the LP lamp. Results of this study suggested that the VUV-amalgam lamp can be applied as a potential substitute for a conventional LP lamp for surface disinfection and limited water disinfection if ozone generation is well controlled.