A model for predicting the growth of Listeria monocytogenes in packaged whole milk

Experiments were conducted to determine growth characteristics of Listeria monocytogenes in sterilized whole milk at nine temperatures in the range of 277.15 to 308.15K (4 to 35C). Based on these data, the parameter values of the Baranyi dynamic growth model were statistically determined. Finite ele ment software, ANSYS, was used to determine temperature distributions in mi lk cartons subject to a time-varying ambient temperature profile. The space -time-temperature data were input to the Baranyi dynamic growth model, to p redict the microbial population density distribution and the average popula tion density in the milk carton. The Baranyi dynamic growth model and the f inite element model were integrated and validated using experimental result s from inoculated sterilized whole milk in half-gallon laminated paper cart ons. In all experiments, the milk cartons were subjected to the same temper ature profile as the Baranyi dynamic growth model. Experimental microbial c ounts were within predicted upper and lower bounds obtained using the integ rated Baranyi dynamic growth and finite element models. In addition, the gr owth curve at the mean value of initial physiological state parameter for L . monocytogenes underpredicted the microbial growth (standard error = 0.54 log (cfu/mL) and maximum relative difference = 15.49%).