Growth Competition between Lactic Acid Bacteria and Listeria monocytogenes during Meat Fermentation – A Mathematical Modeling

Authors: Huang, Lihan; Hwang, Cheng An; Liu, Yanhong; Renye, John; JIA, ZHEN - Fujian Agricultural & Forestry University

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2022
Publication Date: 6/26/2022
Citation: Huang, L., Hwang, C., Liu, Y., Renye Jr, J.A., Jia, Z. 2022. Growth competition between lactic acid bacteria and Listeria monocytogenes during meat fermentation – A Mathematical Modeling. Food Control. 158(2022):111553. https://doi.org/10.1016/j.foodres.2022.111553.
DOI: https://doi.org/10.1016/j.foodres.2022.111553

Interpretive Summary: Listeria monocytogenes is a major foodborne pathogen often associated with processed meat products. It may survive and grow during fermentation, a traditional method for meat processing. The objective of this study was to investigate the interaction and competition between L. monocytogenes and LAB during meat fermentation. The results showed that L. monocytogenes could be effectively controlled by LAB during meat fermentation. Mathematical models were developed to describe the competition between L. monocytogenes and LAB and the changes in water activity and pH. The results of this study may be used by the food industry to properly develop fermented meat products while preventing the growth of L. monocytogenes.

Technical Abstract: Listeria monocytogenes is a significant foodborne health hazard in many products. While fermentation is a traditional method for meat preservation, L. monocytogenes may survive and grow during the fermentation process if raw ingredients are contaminated. The objective of this study was to investigate the growth kinetics of lactic acid bacteria (LAB) in competition with L. monocytogenes during meat fermentation. Sausage meat mixtures made from irradiation-sterilized ground beef (90% lean), salt, sugar, and nitrite were inoculated with a 4-strain cocktail of LAB (107 CFU/g), including 2 Lactobacillus plantarum and 2 Lb. brevis strains, and a 5-strain cocktail of L. monocytogenes (105 CFU/g), first individually and then in combination, and placed in a moisture-controlled environmental chamber (30 °C, relative humidity 76%) for fermentation for 5 days. The changes in the populations of LAB and L. monocytogenes were monitored to determine the growth kinetics. The competitive growth between LAB and L. monocytogenes was examined. Without LAB, L. monocytogenes grew in the sausage samples unhindered, causing little change in pH. However, LAB suppressed its growth, causing the sausage to decrease in pH during fermentation. The interaction between LAB and L. monocytogenes could be described by a model modified from the Lotka-Volterra equation. The decreases in sausage pH and aw could be related to fermentation time using segmented linear models. The validation experiments proved that the modified Lotka-Volterra equation could accurately predict the growth of LAB co-inoculated with 3 different levels of L. monocytogenes in sausage samples during fermentation, suggesting that L. monocytogenes could be effectively inhibited by LAB during the fermentation process.