Inactivation of Shewanella putrefaciens by gamma irradiation of red meat and poultry

The resistance of Shewanella putrefaciens ATCC 8071, 8072, and 8073 to gamma radiation was determined in the presence and absence of air on mechanically deboned chicken meat (MDCM). The presence or absence of air (oxygen) did not significantly influence resistance to gamma radiation at 5C, and it was very sensitive with a D-10 value of 0.11 +/- 0.002 kilogray (kGy) on MDCM. A high percentage of cells surviving irradiation were shown by impedance measurements to have suffered injury. The bacteria were significantly more resistant to gamma radiation at temperatures below the freezing point. At a dose of 0.8 kGy lowering the temperature of irradiation by 10 degrees increased the survival of this food spoilage organism by a 1.66 log(10). The type of meat (hamburger, ground beef round, ground pork, and ground turkey breast) did not significantly alter resistance of S. putrefaciens to gamma radiation under identical conditions (D-10 value = 0.18 +/- 0.01 kGy). The minimum radiation dose currently approved for poultry in the USA, 1.5 kGy, should eliminate S. putrefaciens from meats.