This Is AuburnElectronic Theses and Dissertations

Survival of LIsteria monocytogenes on Ready-to-Eat Roast Beef During Refrigeration Storage




Broady, Johnathan

Type of Degree



Animal Sciences


Listeria monocytogenes (LM) is a psychrotrophic bacterium with serious consequences to human health. Listeriosis causes an estimated 1600 sicknesses and 260 deaths annually in the United States with the primary source of transmission being the consumption of contaminated foods, most frequently from ready-to-eat foods. Ready-to-eat (RTE) is a term applied to those products which require no cooking or heating before consumption. The lack of required heating associated with RTE products provides a unique level of food borne risk. To ensure the safety of these RTE products, antimicrobials such as diacetate and lactate are often added to limit bacterial growth. Despite strict regulations and monitoring of food borne pathogens during fabrication and packaging, contamination of RTE products can simply occur after the product has been opened. As a saprophytic organism LM can enter the food industry from a variety of sources and persist on food processing equipment through the formation of biofilms. These microbial communities can serve as reservoirs for pathogens and contamination of foods often occurs from contact with unclean surfaces. Although LM is of great concern due to its potentially serious clinical outcomes, limited information is available regarding the behavior of this pathogen under home storage conditions. Furthermore, the role of background microflora on LM survival is unclear. The identification and analysis of LM growth will be useful in generating more effective strategies to prevent future outbreaks. The objective of this research was to evaluate the survival of deli roast beef in simulated home storage.