Efficiency of slightly acidic electrolyzed water for inactivation of Salmonella enteritidis and its contaminated shell eggs

Abstract

The efficiency of slightly acidic electrolyzed water (SAEW) at different temperatures (4, 20 and 45 °C) for inactivation of Salmonella enteritidis and it on the surface of shell eggs was evaluated. The bactericidal activity of SAEW, sodium hypochlorite solution (NaClO) and acidic electrolyzed water (AEW) to inactivate S. enteritidis was also compared. SAEW with a pH value of 6.0–6.5 used was generated by the electrolysis of a dilute hydrochloric acid (2.4 mM) in a chamber without a membrane. Although the pH value of SAEW was greatly higher than that of AEW (pH2.6–2.7), SAEW had a comparative powerful bactericidal activity at the same available chlorine concentrations. The efficiency of SAEW for inactivation of pure S. enteritidis cultures increased with increasing the available chlorine concentration and treatment time at the three different temperatures. The S. enteritidis counts decreased to less than 1.0 log 10 CFU/ml at available chlorine of 2 mg/l and 100% inactivation (reduction of 8.2 log 10 CFU/ml) was resulted in using SAEW with available chlorine more than 4 mg/l at 4, 20 and 45 °C after 2 min treatment, whereas no reduction was observed in the control samples. Moreover, SAEW was also effective for inactivating the S. enteritidis inoculated on the surface of shell eggs. A reduction of 6.5 log 10 CFU/g of S. enteritidis on shell eggs was achieved by SAEW containing 15 mg/l available chlorine for 3 min, but only a reduction of 0.9–1.2 log 10 CFU/g for the control samples. No survival of S. enteritidis was recovered in waste wash SAEW after treatment. The findings of this study indicate that SAEW may be a promising disinfectant agent for the shell egg washing processing without environmental pollution.