Modeling the growth of Listeria monocytogenes in mold-ripened cheeses

Abstract

This study presents possible applications of predictive microbiology to model the safety of mold-ripened cheeses with respect to bacteria of the species Listeria monocytogenes during (1) the ripening of Camembert cheese, (2) cold storage of Camembert cheese at temperatures ranging from 3 to 15°C, and (3) cold storage of blue cheese at temperatures ranging from 3 to 15°C. The primary models used in this study, such as the Baranyi model and modified Gompertz function, were fitted to growth curves. The Baranyi model yielded the most accurate goodness of fit and the growth rates generated by this model were used for secondary modeling (Ratkowsky simple square root and polynomial models). The polynomial model more accurately predicted the influence of temperature on the growth rate, reaching the adjusted coefficients of multiple determination 0.97 and 0.92 for Camembert and blue cheese, respectively. The observed growth rates of L. monocytogenes in mold-ripened cheeses were compared with simulations run with the Pathogen Modeling Program (PMP 7.0, USDA, Wyndmoor, PA) and ComBase Predictor (Institute of Food Research, Norwich, UK). However, the latter predictions proved to be consistently overestimated and contained a significant error level. In addition, a validation process using independent data generated in dairy products from the ComBase database (www.combase.cc) was performed. In conclusion, it was found that L. monocytogenes grows much faster in Camembert than in blue cheese. Both the Baranyi and Gompertz models described this phenomenon accurately, although the Baranyi model contained a smaller error. Secondary modeling and further validation of the generated models highlighted the issue of usability and applicability of predictive models in the food processing industry by elaborating models targeted at a specific product or a group of similar products.

Analysis and mathematical modelling of the behaviour of Escherichia coli in the mascarpone cheese during cold storage

“…The A f values within range 1.3–1.5 are also recognised as acceptable predictions. The calculated value of A f (1.08) for elaborated secondary model demonstrated that the predictions of the polynomial model are within acceptable limits (Ross, ; Giffel & Zwietering, ; Lobacz et al ., ).…”

Development of a predictive model describing the growth of Yersinia enterocolitica in Camembert‐type cheese

“…CP is based on experimental data generated in microbiological media. Higher values of GR generated with CP could have been caused by a lack of microbiota which competes for nutrients and is found in Camembert‐type cheese varieties as fermentation starters (Irlinger & Mounier, ; Lobacz et al ., ).…”

Modeling the kinetics of survival of Staphylococcus aureus in regional yogurt from goat's milk

“…One of the most important extrinsic factors limiting the growth and survival of microorganisms is the storage temperature of the product (Lobacz et al 2013). Mesophilic microorganisms, including S. aureus, show a lack of growth at temperatures of 4-6 o C. Growth temperatures of S. aureus were determined in the range of 7-48.5 o C (Valero et al 2009).…”

“…These models are among the most commonly used mathematical models for modeling the survival of bacteria on the nonlinear nature of these changes (Xiong et al 1999, McKellar and Lu 2004, Huang 2009, Lobacz et al 2013.…”