Growth Kinetics of Listeria monocytogenes in Broth and Beef Frankfurters—Determination of Lag Phase Duration and Exponential Growth Rate under Isothermal Conditions

Abstract

The objective of this study was to develop a new kinetic model to describe the isothermal growth of microorganisms. The new model was tested with Listeria monocytogenes in tryptic soy broth and frankfurters, and compared with 2 commonly used models-Baranyi and modified Gompertz models. Bias factor (BF), accuracy factor (AF), and root mean square errors (RMSE) were used to evaluate the 3 models. Either in broth or in frankfurter samples, there were no significant differences in BF (approximately 1.0) and AF (1.02 to 1.04) among the 3 models. In broth, the mean RMSE of the new model was very close to that of the Baranyi model, but significantly lower than that of the modified Gompertz model. However, in frankfurters, there were no significant differences in the mean RMSE values among the 3 models. These results suggest that these models are equally capable of describing isothermal bacterial growth curves. Almost identical to the Baranyi model in the exponential and stationary phases, the new model has a more identifiable lag phase and also suggests that the bacteria population would increase exponentially until the population approaches to within 1 to 2 logs from the stationary phase. In general, there is no significant difference in the means of the lag phase duration and specific growth rate between the new and Baranyi models, but both are significantly lower than those determined from the modified Gompertz models. The model developed in this study is directly derived from the isothermal growth characteristics and is more accurate in describing the kinetics of bacterial growth in foods.

Effect of pH and storage conditions on Listeria monocytogenes growth inoculated into sapote mamey (Pouteria sapota (Jacq) H.E. Moore & Stearn) pulp

“…The modified Gompertz model is frequently used to interpret growth and inactivation curves of microorganisms under isothermal conditions (Bhaduri et al, 1991;Castro, Schmidt, & Penteado, 2007;Gibson, Bratchell, & Roberts, 1987;Huang, 2008;Uchima et al, 2008), and is expressed as:…”

“…With regard to hurdles in foods, it has been observed that pH values equal to or lower than 4.4 can limit its growth, depending on the organic acid present and the constituent elements of the food itself (Beales, 2004;FDA, 2008;Huang, 2008). This microorganism can survive freezing temperatures as well as normal refrigeration temperatures.…”

Modeling the Growth of Byssochlamys fulva on Solidified Apple Juice at Different Temperatures

“…The ability of the Linear-with-breakpoint (LIN) (Dantigny et al 2005), Baranyi and Roberts (BAR) (Baranyi et al 1993;Baranyi and Roberts 1994), and Huang (HUA) (Huang 2008) models (without upper asymptote) to describe the experimental data were assessed in this study. The LIN model was used to describe only the linear growth phase (Equation (1)).…”

“…The differential equations of the BAR and HUA original models were reduced so as not to consider the stationary growth phase (upper asymptote). For all models, D(t) is the colonies' diameter (mm) at the time t (day), µ max is the maximum growth rate (mm/day), λ is the adaptation time (day), and α (1/day) is an empirical curvature parameter, fixed as suggested by the author (α = 25) (Huang 2008).…”

Application of Baranyi function to model the antibacterial properties of solvent extract from Irish York cabbage against food spoilage and pathogenic bacteria

“…The empirical sigmoidal type models such as the modified Gompertz and Logistic models or the biological-based Baranyi model have been used for fitting bacterial growth (Huang, 2008). However, data on the use of actual plant extract for inhibiting microbial growth and modeling the resulting kinetics is scarce.…”