Submitted to: Meat Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 28, 2010
Publication Date: June 1, 2010
Citation: Porto Fett, A.C., Campano, S., Oser, A., Smith, J., Call, J.E., Luchansky, J.B. 2010. Control of Listeria monocytogenes on commercially-produced frankfurters prepared with and without potassium lactate and sodium diacetate and surface .....using the Sprayed Lethality in Container (SLIC®) delivery method. Meat Science. 85:312-318. Interpretive Summary: Listeria monocytogenes continues to cause an appreciable number food borne illnesses and is responsible for numerous and costly product recalls, particularly for ready-to-eat (RTE)red meat and poultry products such as frankfurters. Thus, there has been considerable research directed to develop interventions to keep this bacterium from coming into contact with such products and/or for eliminating or suppressing it if present. To this end, we evaluated the inclusion of select food grade chemicals, namely lactate and diacetate, as ingredients in frankfurters in combination with the addition of a different food grade chemical, namely lauric arginate, to the package per se as a strategy to inhibit L. monocytogenes. The results were very encouraging. Inclusion of lactate/diaceate as ingredients prevented outgrowth of the pathogen during extended refrigerated storage, and surface treatment with lauric arginate generated an initial kill of the pathogen. This double-winged approach provides a safer product, at a lower cost, and should result in fewer illnesses from frankfurters and other RTE meats produced and treated in this manner.
Technical Abstract: The viability of Listeria monocytogenes was monitored on commercially-produced frankfurters that were formulated with no, low, or high levels of potassium lactate and sodium diacetate (low = 0.68% lactate and 0.097% diacetate and high = 1.36% lactate and 0.19% diacetate) and then treated with 22 or 44 ppm of a solution of lauric arginate (LAE; Ethyl-N-dodecanoyl-L-arginate hydrochloride). Frankfurters were removed aseptically from the original package, re-packaged (8 links per bag; 454 grams total) into nylon-polyethylene bags, and then surface inoculated with 2 ml of a five-strain mixture of L. monocytogenes to achieve a target level of ca. 3.3 log CFU/package. Each package was then massaged by hand for ca. 20 seconds to distribute the inoculum, and then 4 ml of LAE was delivered into each package using the Sprayed Lethality in Container (SLIC®) delivery method. Control packages were treated with 4 ml of 0.1% peptone water. The packages were vacuum-sealed and stored at 4 deg C for up to 120 days. The pathogen was recovered from frankfurters using the USDA/ARS package rinse method. For each of two trials, three packages were sampled at each sampling interval. In the absence of any antimicrobials, pathogen numbers remained relatively constant for about 30 days, but then increased to ca. 8.4 log CFU/package over 120 days. Regardless of whether or not lactate and diacetate were included in the formulation, when treated with 22 or 44 ppm of LAE, numbers decreased from ca. 3.3 log CFU/package to ca. 1.5 log CFU/package within 2 hours. However, after 30 days, for frankfurters that did not contain added lactate and diacetate, but that were subsequently treated with 22 or 44 ppm of LAE, pathogen numbers increased to 7.3 and 6.7 log CFU/package, respectively, after 120 days. Of note, when frankfurters were formulated with either low or high levels of lactate and diacetate and surface treated via SLIC® with 22 or 44 ppm of LAE, pathogen numbers decreased by ca. 2.0 log CFU/package within 2 hours and remained relatively unchanged over the 120 days of refrigerated shelf life. These data confirm that LAE provides an initial lethality and when used in combination with lactate and diacetate as an ingredient provides inhibition throughout shelf life. As such, manufacturers may consider this strategy to achieve Alternative 2 status, and possibly Alternative 1 status, for ensuring the safety of RTE meat and poultry products from L. monocytogenes.