Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2010
Publication Date: 5/1/2011
Citation: Grosulescu, C., Ravishankar, S., Juneja, V.K. 2011. Effects and interactions of sodium lactate, sodium diacetate, and pediocin on the thermal inactivation of starved cells of Listeria monocytogenes on the surface of bologna. Food Microbiology. 28:440-446. Interpretive Summary: Listeria monocytogenes has become a pathogen of major concern for the food industry since documentation of its association with several outbreaks of foodborne illness. Undercooked meat and meat products are commonly implicated as transmission vehicle in these outbreaks. This emphasizes the need to better define and quantify the heat treatment given to these foods to provide an adequate degree of protection against survival of Listeria monocytogenes. We developed a mathematical model for predicting the destruction of this pathogen in bologna. The model can be used to predict the time required at any temperature to kill a certain number of bacteria. This information will be of immediate use to consumers and to the food industry and regulatory agencies to aid in the development of guidelines to ensure safety of the food supply.
Technical Abstract: The effects and interactions of temperature (56.3-60C) sodium lactate (SL; 0-4.8%), sodium diacetate (SDA; 0-2.5%), and pediocin (0-10,000 AU) on starved Listeria monocytogenes on bologna were investigated. Bologna slices containing SL and SDA in the formulation were dipped in pediocin, surface inoculated, and treated at various temperatures using combinations of parameters determined by central composite design. D-values were calculated. The observed D-values ranged from 2.8 min at 60C to 24.61 min at 56.3C. Injury ranged from 9.1-76% under various conditions. The observed D-values were analyzed using second order response surface regression for temperature, SL, SDA, and pediocin, and a predictive model was developed. Predicted D-values were calculated and ranged from 3.7-19 min for various combinations of parameters. Temperature alone reduced the predicted D-values from 33.96 min at 60C to 11.51 min at 56.3C. Addition of SL showed a protective effect. Other combination treatments either reduced or increased D-values depending on temperature. The combination of SL and SDA was effective at lower temperatures, however, higher levels of SDA at higher temperatures rendered the organism more heat resistant. Pediocin (upto 5000AU) with temperature and SDA reduced D-values. Depending on temperature and concentration, the interactions between various additives can affect thermal inactivation of L. monocytogenes on bologna. Starvation rendered L. monocytogenes more susceptible to heat and additives.