Purpose: This study was undertaken to investigate the efficacy of selected commercial disinfectants in the elimination of Salmonella from food contact surfaces inoculated with Salmonella cells at log, stationary, and LTS phases.
Methods: Laminate, stainless steel, and plastic cutting board surfaces were inoculated with Salmonella harvested at log, stationary, and LTS phases, using three different microbial loads (106, 104, and 102 CFU/cm2). Sodium hypochlorite (0.0095%), acetic acid, and hydrogen peroxide (0.88%) were used for surface disinfection at 0, 2, and 24 h. Residual bacteria were recovered by elution and log reduction of Salmonella was calculated. A CRD split plot design was used to analyze results.
Results: All disinfectants reduced surface microbial load, significantly, for all microbial concentrations, for all phases, at all time points, and on all tested surfaces. Hydrogen peroxide had an overall mean log reduction equal to 3.15 log10CFU/cm2 ± 0.03 compared to 1.86 log10CFU/cm2 ± 0.03 and 2.97 log10CFU/cm2 ± 0.03 for sodium hypochlorite and acetic acid, respectively. LTS cells seemed to be more resilient to sodium hypochlorite, with the lowest overall mean log reduction being 1.27 log10CFU/cm2 ± 0.08 for laminate surface (p<0.001). All main effects for this study (phase, type of surface, time, treatment, and concentrations), as well as interactions, were significant (p<0.004).
Significance: These data suggest that disinfection efficacy of surfaces infected with Salmonella depends on multiple factors that must be considered in order to achieve sanitation.