Bactericidal activity of strong acidic hypochlorous water against Escherichia coli O157:H7 and Listeria monocytogenes in biofilms attached to stainless steel

This study aims to investigate the bactericidal activity of strong acidic hypochlorous water (SAHW) against Escherichia coli O157:H7 and L. monocytogenes in bacterial biofilms. The bactericidal activity of SAHW against both bacteria in colony biofilm increased with the elevation of the available chlorine concentration (ACC) and extension of the treatment time. The survived cell counts of E. coli O157:H7 and L. monocytogenes in the biofilms were significantly (p < 0.05) decreased compare to tap water at more than 30 mg/L of ACC in SAHW and 15 s of treatment time. E. coli O157:H7 and L. monocytogenes in the biofilms reduced to less than the detection limit by treatment of 50 mg/L of ACC in SAHW for 300 and 600 s, respectively. SAHW may be a potential disinfecting agent for removing bacterial biofilms from food processing equipment and other facilities.