Modeling the Effect of Abrupt Acid and Osmotic Shifts within the Growth Region and across Growth Boundaries on Adaptation and Growth of Listeria monocytogenes

Abstract

Skandamis, submitted for publication) on the effects of osmotic and pH shifts on the kinetics of L. monocytogenes. The predictive ability of the model was assessed on new data in milk. The effects of shifts were modeled through the dependence of the parameter h 0 ("work to be done" prior to growth) induced on the magnitude of the shift and/or the stringency of the new environmental conditions. For shifts across the boundary, the lag time was found to be affected by the length of time for which the microorganisms were kept at growth-inhibiting conditions. The predicted concentrations of L. monocytogenes in milk were overestimated when the effects of this shift were not taken into account. The model proved to be suitable to describe the effects of osmotic and acid shifts observed both within the growth domain and across the growth boundaries of L. monocytogenes.

Establishing Equivalence for Microbial-Growth-Inhibitory Effects (“Iso-Hurdle Rules”) by Analyzing Disparate Listeria monocytogenes Data with a Gamma-Type Predictive Model

“…Our data, completed by a few sets of ComBase data, indicated that the hypothesis of a constant amount of work (32) might be questioned when NaCl is used as a preservative factor, in stress conditions. That is in line with recent results reported in the literature showing a specific effect of NaCl on L. monocytogenes lag time (23,25). For practical application of the methodology developed in the present study and illustrated with L. monocytogenes, the following conclusions could be drawn.…”

Combining Individual-Based Modeling and Food Microenvironment Descriptions To Predict the Growth of Listeria monocytogenes on Smear Soft Cheese

“…The simulations could be refined by modeling the effect of the shifts in pH and a w when L. monocytogenes cells are inoculated on the cheese surfaces (43). However, this simplification seemed acceptable, since simulated count distributions were close to the observed ones even for young cheeses with the lowest pH (Fig.…”

Modelling the effects of temperature and osmotic shifts on the growth kinetics of Bacillus weihenstephanensis in broth and food products

“…Further studies (e.g. Le Marc et al, 2010;Muñoz-Cuevas et al, 2010) found that h 0 depends not only on the magnitude of the change between the previous and the current conditions but also on the conditions prevailing after shifts. In most of these studies, the models developed for h 0 were not validated in food products.…”

“…In most of these studies, the models developed for h 0 were not validated in food products. An attempt to apply a model developed for the lag time of Listeria monocytogenes induced by abrupt changes in the environmental conditions during the growth phase (intermediate lag time) in BHI to experiments in milk was made by Le Marc et al (2010). In their study on the effects of osmotic stress on the lag time of Salmonella enterica, Zhou et al (2011) found that for the same osmotic stress, the parameter h 0 was significantly different International Journal of Food Microbiology 158 (2012) 36-41 in minimum and rich media.…”