Effects of Ionizing Radiation and Anaerobic Refrigerated Storage on Indigenous Microflora, Salmonella, and Clostridium botulinum Types A and B in Vacuum-Canned, Mechanically Deboned Chicken Meat†

Vacuum-canned, commercial, mechanically deboned chicken meat was challenged with either Clostridium botulinum spores (20 strains of types A and B, proteolytic; final spore concentration of ca. 400/g of meat) or Salmonella enteritidis (ca. 104 CFU/g of meat) followed by irradiation to 0, 1.5, and 3.0 kGy and storage at 5°C for 0, 2, and 4 weeks. None of the samples stored at 5°C developed botulinal toxin; however, when these samples were temperature abused at 28°C they became toxic within 18 h and had obvious signs of spoilage, i.e., swelling of the can and a putrid odor. During 4 weeks of refrigerated storage the log10 of the population of S. enteritidis in nonirradiated samples decreased from 3.86 to 2.58. S. enteritidis CFU were detectable in samples irradiated to 1.5 kGy at 0 weeks but not in samples irradiated to 3.0 kGy. Log levels of aerobic and facultative mesophiles increased during 4 weeks of refrigerated storage from 6.54 to 8.25, 4.03 to 8.14, and 2.84 to 5.23 in samples irradiated to 0, 1.5, and 3.0 kGy, respectively. Based on taxonomic analyses of 245 isolates, the bacterial populations depended upon radiation dose and storage time. The change was predominantly from gram-negative rods in nonirradiated samples to gram-positive streptococci in samples irradiated to 3.0 kGy and stored for 4 weeks. Spoilage organisms survived even the 3.0 kGy treatment.