Mathematical modeling on the growth of Staphylococcus aureus in sandwich

Tian Ding, Young-Hwan Shim, Na-Jung Choi, Sang-Do Ha, Myung-Sub Chung, In-Gyun Hwang, Deog-Hwan Oh

                                                                                    

Abstract

The growth of Staphylococcus aureus in sandwich fillings at different incubation temperatures was tested. These growth data were fitted into the Gompertz model, Logistic model, and Baranyi model in order to compare the goodness-of-fit of the 3 primary models using several factors such as coefficient of determination (R²), the standard deviation (S_y.x), and the Akaike’s information criterion (AIC). The Gompertz model showed the best statistical fit. Hence, growth parameters such as specific growth rate (SGR) and lag time (LT) obtained from the Gompertz model were used to construct the secondary models. Further, developed models were evaluated by bias factor (B_f) and accuracy factor (A_f). For the SGR, the Bf value was 0.993 and A_f value was 1.156 which indicated conservative predictions. While for LT, a clear deviation was observed between predictions and observations (B_f=0.635 and A_f=1.592). The results, however, were also considered acceptable after comparing with previous publications.

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Keywords :Staphylococcus aureus ,rimary model ,secondary model ,sandwich ,evaluation.