COMPARISON OF RESPONSE-SURFACE MODELS FOR LISTERIA-MONOCYTOGENES STRAINS UNDER AEROBIC CONDITIONS

A factorial experimental design was employed to measure the effects of temperature (4-41 degrees C), pH (5.5-7.7), NaCl concentration (0.5-5.5%) and NaNO2 concentration (0-125 ppm) on the growth kinetics of two food-derived strains of Listeria monocytogenes in buffered tryptose phosphate broth. Response surface models for both strains were produced from these data. Comparisons between these models, a published model for strain Scott A and measured kinetic data showed that the model for strain Scott A was generally better at predicting lag times while the model for one of the food-derived isolates was better at predicting generation times. A combination of these models was found to provide reasonable predictions of growth on fleshfood substrates when compared to the measured kinetic data