Abstract: The main objective of this study was to develop the primary and secondary models to describe the growth kinetics of Salmonella and background microorganisms in chicken. Samples inoculated with a cocktail of two Salmonella serotypes, S. typhimurium (CICC22956) and S. enteritidis (CICC21482) were incubated at 8, 12, 16, 20, 25, 30, 33, 37, 40 or 43 ℃. Salmonella grew well at all temperatures (12 to 43 ℃) except at 8 ℃. The growth kinetics of Salmonella and background microorganisms at the temperatures were analyzed by curve-fitting to the Huang and Baranyi models using the USDA Integrated Pathogen Modelling Program. The results showed that there was no significant difference between the two models in terms of their ability to accurately predict the growth of Salmonella and background microorganisms in chicken. Three secondary models, the Ratkowsky square-root (RSR) Huang square-root (HSR), and Cardinal models, were all could be used to evaluate the effect of temperature on the growth rate of bacteria. The Cardinal model underestimated the growth rates of the microorganisms at low temperatures. The minimum and maximum growth temperatures of Salmonella predicted by the HSR model (7.81 and 49.67 ℃, respectively) were closer to the literature reported values. The Ratkowsky square-root model was more suitable for describing the growth rate of the background microorganisms in a wide temperature range. These results may be useful for the food industry and the regulatory bodies to predict the growth of Salmonella in chicken and to perform risk assessments concerning the presence of this pathogen in meat products.

Key words: chicken, Salmonella, primary model, secondary model, growth kinetics