Radiation Sensitivity of Listeria monocytogenes on Beef as Affected by Temperature

Longissimus dorsi from beef was inoculated with Listeria monocytogenes and the effect of gamma irradiation on the survival of this pathogen at −60 to +15°C was determined. Radiation D‐values were determined for inactivation of L. monocytogenes at 5°C intervals from −20 to 5°C. These data were used to develop an equation to predict the response to gamma radiation within that range. An abrupt increase in resistance occurred at −5°C. The radiation D‐value was 0.45 kGy at 0°C, 0.77 kGy at −5°C and 1.21 kGy at −20°C. A straight line was obtained when the log 10 of the D‐values from −5 to −20°C was plotted vs the reciprocal of the absolute temperature. This led us to calculate a value analogous to the Arrhenius activation energy for inactivation of L. monocytogenes by gamma radiation.