Bactericidal efficacy of slightly acidic electrolyzed water (SAEW) against Listeria monocytogenes planktonic cells and biofilm on food-contact surfaces

In the present study, the bactericidal efficacy of slightly acidic electrolyzed water (SAEW) against Listeria monocytogenes (L. monocytogenes) planktonic cells and biofilm on food-contact surfaces including stainless steel and glass was systematically evaluated. The results showed that SAEW (pH 5.09 and available chlorine concentration (ACC) of 60.33 mg/L) could kill L. monocytogenes on food-contact surfaces completely in 30 s, a disinfection efficacy equal to that of NaClO solutions (pH 9.23 and ACC of 253.53 mg/L). The results showed that long exposure time and high ACC contributed to the enhancement of the disinfection efficacy of SAEW on L. monocytogenes on food-contact surfaces. Moreover, the log reduction of SAEW treatment presented an increasing tendency within the prolonging of treatment time when SAEW was used to remove the L. monocytogenes biofilm formed on stainless steel and glass surfaces, which suggested that SAEW could remove L. monocytogenes biofilm effectively and its disinfection efficacy is equal to (in the case of stainless steel) or higher than (in the case of glass) that of high-ACC NaClO solutions. In addition, the results of the crystal violet staining and scanning electron microscopy also demonstrated that SAEW treatment could remove the L. monocytogenes biofilm on food-contact surfaces.