The destruction of Salmonella bacteria in refrigerated liquid whole egg with gamma radiation

Abstract

Thermal pasteurization being a borderline process, it was attempted to use ionizing radiation for rendering whole egg, intended for preservation by other methods than freezing, free from Salmonelleae. Initial densities of about 107/ml of S. typhimurium and S. senftenberg were used. Irradiation was carried out with a ca. 1500 c Co60-source, the inoculated whole egg being packed in lacquered tins and kept at ca. 1°C during this treatment.

Six decimal reductions of the Salmonella-species tested were obtained at dosages of 2 × 105 rad, nine reductions at slightly over 5 × 105 rad. No effect of the use of specific recovery media or pre-treatments on the apparent dose value required for obtaining these reductions could be established.

The odour of the whole egg and its functional properties appeared to have been impaired at dosages of 104 rad, while the colour suffered from ca. 2 × 105 rad. Therefore, the radiation pasteurization of liquid whole egg at ca. 1°c cannot be considered a promising process.