Effect of microstructure and initial cell conditions on thermal inactivation kinetics and sublethal injury of Listeria monocytogenes in fish-based food model systems. (December 2019)

• Record Type: Journal Article
• Authors: Verheyen, Davy; Baka, Maria; Akkermans, Simen; Skåra, Torstein; Van Impe, Jan F.
• Is Part Of: Food microbiology. Volume 84(2019)
• Publication Date: 2019-12
• Subjects: Food safety -- Predictive microbiology -- Thermal inactivation -- Sublethal injury; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2019.103267
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: The development of more accurate predictive models that describe the microbial kinetics of mild thermal treatments of foods requires knowledge concerning the influence of food microstructure and initial cell conditions on foodborne pathogens' inactivation kinetics. The effect of food microstructure and initial cell conditions on thermal inactivation kinetics and sublethal injury (SI) of Listeria monocytogenes was investigated at 59, 64 and 69°C . Fish-based food model systems with different microstructures, possessing minimal compositional and physicochemical variations, were used. L. monocytogenes growth morphology had no significant influence on thermal inactivation kinetics. A gelled matrix resulted in a lower specific inactivation rate k max and a higher residual cell population N res, while the presence of fat droplets resulted in a higher k max and did not influence N res . SI was higher in viscous than in gelled systems and more prominent for cells that were grown inside the matrix. Hence, predictive thermal inactivation models could benefit from the inclusion of factors related to the nature of the food matrix and fat properties. Starting inactivation from cells that were grown inside the matrix, resulted in lower (i.e., fail-safe) k max values and more uncertainty on N res as compared to starting from cells grown at optimal conditions. Highlights: Lower k max and higher N res of L. monocytogenes in a gelled vs. viscous matrix. Higher k max in the presence of fat droplets . Lower k max for cells grown in matrix vs. optimal conditions. SI was higher in viscous matrix than in gelled matrix . Cells grown in model system matrix exhibit more SI during inactivation .