Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2009
Publication Date: 6/1/2010
Citation: Maks, N., Zhu, L., Juneja, V.K., Ravishankar, S. 2010. Sodium lactate, sodium diacetate and pediocin: effects and interactions on the thermal inactivation of Listeria monocytogenes on bologna. Food Microbiology. 27:64-69. 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 (56.3C-60C), sodium lactate (SL; 0-4.8%), sodium diacetate (SD; 0-0.25%) and pediocin (0-10,000 AU) on Listeria monocytogenes inoculated on bologna were studied and a predictive inactivation model was developed. Bologna was manufactured with different SL and SD concentrations in the formulation, then dipped in pediocin solution and treated in a heated water bath using combinations of parameters as determined by central composite design. The observed D-values for L. monocytogenes on bologna with various concentrations and combinations of antimicrobials ranged from 2.10-35.59 min. Predicted D-values were calculated from survivor curves and analyzed using second order response regression for all combinations. The use of temperature alone decreased predicted D-values from 99.02 min at 56.3C to 44.71 min at 60.0C. Adding SL, decreased D-values further; however, heat and SD combined was the most effective for reducing L. monocytogenes on the bologna. An SD level of 0.25% at 58.2C had the overall lowest predicted D-value (15.95 min). Combining SL and SD at 56.3C or 60C decreased D-values at lower SL concentrations. Pediocin (2500 and 5000 AU) and heat initially decreased D-values but then exhibited a protective effect as the pediocin concentration was increased. The model developed can predict D-values for any combination of temperature, SL, SD and pediocin within the levels tested for L. monocytogenes on the bologna. The results of this study showed that the interactions between the various additives in a formulation vary at different temperatures and at different concentrations, and can accordingly affect the inactivation of foodborne pathogens during thermal treatment of meat products. Hence, food processors should change/modify the food formulations with caution and verify with adequate testing so that the safety of the food product is not compromised.