Mathematical modeling of growth of Salmonella paratyphi B and Staphylococcus aureus in ready-to-eat cucumber slices

Fresh-cut cucumber slices which were inoculated with Salmonella paratyphi B were incubated under constant temperature conditions between 10, 15, 20, 25, 30 and 35℃ to observe the growth of bacteria. The growth curves of each bacterium under each temperature were analyzed using the USDA Integrated Pathogen Modeling Program(USDA-IPMP)to find the most suitable primary models for describing the bacterial growth. The effect of temperature on bacterial growth rate and lag time was also evaluated using various secondary models. Experimental data and growth curves showed that the growth of Salmonella paratyphi B exhibited three phases, including lag, exponential, and stationary phases. The lag time of each bacterium decreased as the incubation time increased. In contrast, the growth rate of both bacteria increased with the incubation temperature, suggesting increased risks at elevated temperatures during temperature abuse. The growth curves of both pathogens were analyzed with the Baranyi and Huang primary models, while the Ratkowsky and Huang square-root models, Cardinal and the Arrhenius-type model were used to describe the effect of temperature on bacterial growth during storage. The predictive models were validated using experimental data. The results and predictive models obtained from this study can be used to predict the growth of Salmonella paratyphi B in fresh-cut RTE cucumber products.