RISK ASSESSMENT OF LISTERIA MONOCYTOGENES IN REFRIGERATED ACIDIFIED FOOD PRODUCTS: DATA GENERATION FOR DEVELOPMENT OF A GROWTH/NO GROWTH MODEL

Probabilistic models are very useful to assess the likelihood that a microorganism can multiply at specific conditions.
This research was focused on the growth/no growth boundary of Listeria monocytogenes in foods acidified with acetic acids (e.g. mayonnaise based salads). In this study the influence of pH (5.0 – 6.0), water activity (0.960 – 0.985) and acetic acid (0 – 0.8 % (w/w)) on the growth/no growth boundary was examined in order to develop a growth/no growth model for these kind of products at refrigerated temperature.
The results showed that the water activity did not have much influence on the growth boundary in the range from 0.960 to 0.985. The largest shift in the boundary was found at the transition from pH 5.6 to 5.4 if no acetic acid was present.
If the concentration of acetic acid increased to 0.2 % (w/w) this shift was situated at the transition from pH 5.8 to 5.6. At a concentration of 0.4 % (w/w), there was only growth at the highest water activities and pH’s.

III International Symposium on Applications of Modelling as an Innovative Technology in the Agri-Food Chain; MODEL-IT

A. Vermeulen, K. Gysemans, K. Bernaerts, A.H. Geeraerd, J.F. Van Impe, J. Debevere, F. Devlieghere

predictive modelling, water activity, pH, acetic acid

https://doi.org/10.17660/ActaHortic.2005.674.32