Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2002
Publication Date: 4/20/2003
Citation: Murphy, R.Y., Duncan, L.K., Driscoll, K.H., Beard, B.L., Berrang, M.E., Marcy, J.A. 2003. Determination of thermal lethality of listeria monocytogenes in fully cooked chicken breast fillets and strips during postcook in-package pasteurization. Journal of Food Protection. 66(4):578-583. Interpretive Summary: Listeria monocytogenes is a human pathogen which has been associated with fully cooked poultry meat products. This organism can thrive in the cool wet environments often found in poultry meat processing plants. Although proper cooking will eliminate L. monocytogenes, cooked product can be re-contaminated prior to packaging. This study addressed that concern by testing a heat pasteurization treatment applied to fully cooked chicken meat after packaging. Fully cooked chicken meat was inoculated with 107 to 108 cells of L. monocytogenes per g, vacuum packaged and exposed to steam or hot water. A five minute heat treatment at 90oC lowered L. monocytogenes levels on fully cooked single packaged fillets by 7 log10 cfu/g. A similar decrease in L. monocytogenes counts was achieved in 454 after 35 minutes and in 227g packages after 25 minutes of treatment. A model was developed to predict thermal lethality of L. monocytogenes in fully cooked poultry meat. This information can be used by processors to develop post cook pasteurization protocols.
Technical Abstract: Fully cooked chicken breast fillets or strips were surface-inoculated to contain 107 - 108 cfu/g of Listeria monocytogenes. The inoculated products were vacuum-packaged and pasteurized via a pilot scale steam or hot water cooker. After treatment, the survivors of L. monocytogenes were enumerated. No significant difference was found on survival rate of L. monocytogenes between steam and hot water treated products. In order to achieve a 7 log10(cfu/g) of reduction, approximately 5 min, 25 min, and 35 min was needed for single-packaged fillets, 227 g package strips, and 454 g strips, respectively. The results from this study were also validated via a computer model that could predict thermal lethality of pathogens in fully cooked meat and poultry products during postcook in-package pasteurization.