A Successful Technique for the Surface Decontamination of Salmonella enterica Serovar Typhimurium Externally Contaminated Whole Shell Eggs Using Common Commercial Kitchen Equipment

Eggs are a highly nutritious food source used in a wide range of food products. In Australia, eggs are a frequent source of foodborne salmonellosis outbreaks, associated with eggshell contamination with Salmonella enterica serovar Typhimurium (ST). Despite their potentially hazardous nature, raw eggs are often used and consumed in mayonnaise, mousse, ice cream and eggnog. The aim of this study was to develop a shell egg decontamination method that removed ST contamination from the outside of an egg without impacting its usability. The decontamination method was developed by the adaptation of a temperature-controlled water bath (commonly present in kitchens and associated with the sous-vide technique) for the surface decontamination of eggs. The outside of whole eggs was artificially inoculated with two ST strains. The eggs were decontaminated by placing in a sous-vide cooker with the water heated to 57°C. The remaining viable ST present on the whole shell egg, crushed shells, internal egg contents and sous-vide water were enumerated over time by culturing onto XLD agar. The quality of the uncontaminated heat-treated eggs was determined by measuring the Haugh unit, yolk index, albumen pH, thermocoagulation, and stability of foam. A blind control study was conducted to assess the acceptability and usability of the treated eggs by chefs and food handlers for the preparation of mayonnaise. Complete decontamination of ST was achieved by treating eggs for 9 min in the sous-vide cooker (57°C). No statistically significant difference was observed in the quality of treated eggs compared with nontreated eggs using the quality measurements and acceptability score from chefs. This method provides a simple approach that can be adopted by chefs and food handlers to obtain safe eggs before the preparation of raw egg products.