GROWTH MODELING OF LISTERIA-MONOCYTOGENES AND YERSINIA-ENTEROCOLITICAIN FOOD MODEL SYSTEMS AND DAIRY-PRODUCTS

The growth potential of Listeria monocytogenes, measured with a gaschr omatographic method, was evaluated in model systems simulating dairy p roducts in which NaCl concentration, pH and lipid concentration ranged from values corresponding to matured hard cheeses to some light chees es and other dairy products. The growth data from the model systems, c alculated on the basis of the polynomial models obtained, were compare d with values observed for dairy products. Growth parameters of Yersin ia enterocolitica in traditional and light cheeses were also available . The comparison between predicted and observed data suggested that in dividual or interactive effects of chemicophysical variables such as p H, salt and lipid concentration are not sufficient to predict the fate of L. monocytogenes in dairy products. Microstructural factors as wel l as the pH effect on water binding capacity of proteins could also be implicated.