Response Surface Model for Predicting the Effects of Temperature pH, Sodium Chloride Content, Sodium Nitrite Concentration and Atmosphere on the Growth of Listeria monocytogenes

Abstract

A factorial plus supplemental central composite experimental design was used to assess quantitatively the effects and interactions of temperature (5°-37°C), pH (4.5-7.5), NaCl (5-45 g/1), NaNO₂ (0-1000 μg/ml), and atmosphere (aerobic vs. anaerobic) on the growth kinetics of Listeria monocytogenes Scott A in Tryptose Phosphate Broth. A total of 709 growth curves were generated, with individual curves fitted using non-linear regression analysis in conjunction with the Gompertz function. The results were analyzed by response surface analysis to generate a cubic model to predict the growth of L. monocytogenes in response to any combination of the variables within the specified ranges. Evaluation of the model indicated that it can be used to provide reasonable "first estimates" of the impact of food formulation and storage conditions on the growth of L. monocytogenes , and can be automated readily to develop "user-friendly" software.