Irradiation and modified atmosphere packaging for the control of Listeria monocytogenes on turkey meat

When radiation-sterilized ground turkey meat was inoculated with Listeria m onocytogenes, packaged under mixtures of nitrogen and carbon dioxide, and i rradiated with gamma-radiation doses of 0 to 3.0 kGy, there was a statistic ally significant (P < 0.05), but probably not a biologically significant, l ower (0.39 log) predicted bacterial survival in the presence of 100% carbon dioxide than in the presence of 100% nitrogen. Possibly because all atmosp heres contained oxygen and because a response surface design was used, gamm a-radiation resistance was not significantly (P < 0.05) different in air th an in modified atmosphere packaging (MAP) mixtures containing 5% O-2 or con taining 20, 40, 60, and 80% CO2 and balance N-2. The antilisterial effects of MAP mixtures containing 17.2, 40.5, and 64% CO2 and balance N-2 were com pared to those associated with air and vacuum packaging on turkey inoculate d with approximately 5 x 10(3) CFU/g. Samples were irradiated to doses of 0 , 0.5, 1.0, 1.5, 2.0, and 2.5 kGy and were stored at 7 degrees C for up to 28 days. Irradiation treatments were significantly more lethal in the prese nce of air packaging than in either vacuum packaging or MAP and in those sa mples that received >1.0 kGy, there was a concentration-dependent CO2 inhib ition of L. monocytogenes multiplication and/or recovery.