Effect of temperature on the radiation resistance of virulent Yersinia enterocolitica

Yersinia enterocolitica, a food-borne pathogen, can be eliminated from meat using ionizing radiation. Commercial facilities may irradiate meat at refrigeration or frozen temperature, or packed in dry ice if the facility does not have refrigeration capabilities. The effect of temperature on the radiation resistance of Y. enterocolitica that contained the 70 kb large virulence plasmid was determined. A mixture of four Y. enterocolitica strains was inoculated into ground pork, which was then vacuum-packed, equilibrated to refrigeration or sub-freezing temperatures, and irradiated to doses of 0.2, 0.4, 0.6, 0.8, and 1.0 kGy. The D10 value, the radiation dose required to reduce the number of viable Y. enterocolitica by 90%, increased as product temperature decreased with values of 0.19, 0.19, 0.21, 0.40, 0.40. 0.38, and 0.55 kGy being obtained at +5, 0, −5, −10. −15, −20 and −76 °C, respectively. Meat product temperature should be considered when selecting a radiation dose required for elimination of Y. enterocolitica.