Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/23/2005
Publication Date: 1/1/2006
Citation: Murphy, R., Hanson, R.E., Johnson, N.R., Chappa, K., Berrang, M.E. 2006. Combining organic acid treatment with steam pasteurization to eliminate listeria monocytogenes on fully-cooked frankfurters. Journal of Food Protection. 69(1):47-52. Interpretive Summary: Listeria monocytogenes is a human pathogen that can live in the environment of food processing plants. This bacteria is killed by proper heat treatment, but can potentially re-contaminate fully cooked product between cooking and commercial packaging. If such re-contamination occurs, the consumer can be put at risk for life threatening illness. This study was conducted to test the use of steam pasteurization in combination with food grade antimicrobial acids to control L. monocytogenes contamination on fully cooked hot dogs. Hot dogs were surface inoculated with up to a million cells L. monocytogenes per square centimeter. An organic acid solution containing 2% acetic acid, 1 % lactic acid, 0.1 % propionic acid and 0.1% benzoic acid was dripped onto the hot dogs which were then treated with steam at 114 C for 1.5 s and immediately packaged. The steam/acid treatment eliminated up to 100 cells L. monocytogenes per square centimeter and significantly lowered counts when the inoculum was greater than 100 cells per square centimeter. Furthermore, L. monocytogenes that did survive the treatment were not able to grow during refrigerated storage for 19 weeks. These data, relative to organic acids applied with steam pasteurization, provide processors with information that will aid in the development of methods to produce fully cooked meat products that are less likely to be contaminated by L. monocytogenes.
Technical Abstract: In this study, an organic acid solution, including acetic (2%), lactic (1%), propionic (0.1%), and benzoic acid (0.1%), were combined with steam surface pasteurization to treat frankfurters during vacuum packaging to eliminate potentially post-cook contaminated L. monocytogenes. The thermal lethality of L. monocytogenes by steam was evaluated at an inoculation level of 1 to 6 log 10 CFU/cm2. About 3 log reductions of L. monocytogenes were achieved when frankfurters were treated by steam for 1.5 s. Combining organic acid treatment with steam pasteurization further inhibited the growth of survived L. monocytogenes cells for 19 and 14 weeks, respectively, when the packaged frankfurters were stored at 4 and 7ºC. The results from this study provide meat processors useful information to control L. monocytogenes on ready-to-eat meats.