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item Luchansky, John
item Call, Jeffrey

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2003
Publication Date: 5/1/2004
Citation: Luchansky, J.B., Call, J.E. 2004. Evaluation of nisin-coated cellulose casings for control of listeria monocytogenes inoculated onto the surface of commercially-prepared frankfurters. Journal of Food Protection. 67:1017-1021.

Interpretive Summary: Within the past 4 years there have been three large multi-state outbreaks and numerous sporadic cases of listeriosis in the United States. All three of these outbreaks involved ready-to-eat (RTE) meats. As a result, there have been extensive efforts to develop more effective post-processing strategies to control Listeria monocytogenes in RTE meats. One promising approach is the use of biopreservatives such as nisin, which is Generally Recognized As Safe (GRAS) and currently approved for use in select foods. Because of its potential, researchers are actively investigating the use of nisin in combination with a variety of other antimicrobials to control undesirable microbes in foods. To this end, we evaluated the use of nisin-coated cellulose casings as an antilisterial hurdle for frankfurters prepared with potassium and sodium lactate. In general, during 90 days of refrigerated storage levels of L. monocytogenes decreased by 1.15 log10 colony forming units (CFU) per package for frankfurters processed in nisin-coated casings and by 0.95 log10 CFU per package for frankfurters processed in otherwise similar casings that were not coated with nisin. These findings indicate that nisin-coated casings provide only moderate antilisterial activity in addition to that provided by potassium lactate and sodium diacetate. The results of the present study notwithstanding, the use of casings as an antimicrobial delivery vehicle for high-volume, high-risk, small-diameter sausage has potential as a convenient and cost-effective intervention strategy for processors that merits further attention.

Technical Abstract: The present study was conducted to determine if commercially-prepared frankfurters formulated with about 1.4% potassium lactate and 0.1% sodium diacetate that were subsequently processed in cellulose casings coated with and without nisin Z (ca. 50,000 I.U. per square inch of internal surface area) would control the outgrowth of L. monocytogenes during refrigerated storage. The frankfurters were inoculated with approximately 5 log10 CFU per package of a five-strain mixture of L. monocytogenes and then vacuum-sealed before being stored at 4°C for 90 days. Survivors were recovered and enumerated by rinsing each package with 18 ml of sterile 0.1% peptone water and spread plating onto MOX selective agar. The data for each of two trials were averaged. In packages containing frankfurters prepared in nisin Z-coated casings, L. monocytogenes levels decreased by 1.15 log10 CFU per package after 90 days of storage. In comparison, L. monocytogenes levels decreased by 0.95 log10 CFU per package in frankfurters prepared in casings that were not coated with nisin Z. These data establish that cellulose casings coated with nisin Z display only moderate antilisterial activity in vacuum-sealed packages of commercially-prepared frankfurters formulated with potassium lactate and sodium diacetate during storage at 4 C.