Sous Vide Process Found to Decontaminate Eggshell Salmonella

Sous Vide Process Found to Decontaminate Eggshell Salmonella

Australian scientists develop a shell egg decontamination method that removed Salmonella from the outside of an egg without impacting its usability.

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February 5, 2020

Eggs are a known source of foodborne salmonellosis, associated with eggshell contamination with Salmonella enterica serovar Typhimurium. Despite their potentially hazardous nature, raw eggs are often used and consumed in mayonnaise, mousse, ice cream and eggnog.

In a recently published study, scientists from Flinders University in Adelaide, Australia, developed a shell egg decontamination method that removed the Salmonella 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 Salmonella strains. The eggs were decontaminated by placing in a sous-vide cooker with the water heated to 135°F. The remaining viable Salmonella present on the whole shell egg, crushed shells, internal egg contents and sous-vide water were enumerated over time by culturing onto Xylose Lysine Deoxycholate (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 the Salmonella was achieved by treating eggs for nine minutes in the 135°F sous-vide cooker. 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.