Description of Kinetic Behavior of Pathogenic Escherichia coli in Cooked Pig Trotters under Dynamic Storage Conditions Using Mathematical Equations

A dynamic model was developed to predict the Escherichia coli cell counts in pig trotters at changing temperatures. Five-strain mixture of pathogenic E. coli at 4 Log CFU/g were inoculated to cooked pig trotter samples. The samples were stored at 10°C, 20°C, and 25°C. The cell count data was analyzed with the Baranyi model to compute the maximum specific growth rate (μ(max)) (Log CFU/g/h) and lag phase duration (LPD) (h). The kinetic parameters were analyzed using a polynomial equation, and a dynamic model was developed using the kinetic models. The model performance was evaluated using the accuracy factor (A(f)), bias factor (B(f)), and root mean square error (RMSE). E. coli cell counts increased (p<0.05) in pig trotter samples at all storage temperatures (10°C–25°C). LPD decreased (p<0.05) and μ(max) increased (p<0.05) as storage temperature increased. In addition, the value of h(0) was similar at 10°C and 20°C, implying that the physiological state was similar between 10°C and 20°C. The secondary models used were appropriate to evaluate the effect of storage temperature on LPD and μ(max). The developed kinetic models showed good performance with RMSE of 0.618, B(f) of 1.02, and A(f) of 1.08. Also, performance of the dynamic model was appropriate. Thus, the developed dynamic model in this study can be applied to describe the kinetic behavior of E. coli in cooked pig trotters during storage.