An Assessment of the Microbiological Risks Involved with Egg Washing under Commercial Conditions

Abstract

The potential benefits of washing eggs is offset by a historical perception in the European Union that wetted eggs are prone to spoilage and water loss. This study describes the effects of spray jet washing under various processing conditions to shell surface counts ofSalmonella and the presence of bacteria in egg contents. Experiments used eggs that were contaminated withSalmonella Enteritidis PT4 orSalmonella Typhimurium DT104 before cuticle hardening. Washing of contaminated eggs under optimum conditions resulted in a more than 5-log reduction ofSalmonella counts from the shell surface.Salmonella was not isolated from the yolk or albumen of any egg washed by the optimal protocol, suggesting that when properly controlled, egg washing did not causeSalmonella to enter the contents. However, contamination did arise if strict control was not maintained over the wash and rinse water temperatures. BothSalmonella Enteritidis andSalmonella Typhimurium were shown to enter the egg contents when water temperatures were lowered, indicating that strict temperature control must be maintained in order to prevent the ingress ofSalmonella into egg contents. Other washing machine parameters that were investigated did not significantly affectSalmonella entry into the egg contents but influenced shell surface kill levels to varying degrees.