Application of Probabilistic Model to Calculate Probabilities of Escherichia coli O157:H7 Growth on Polyethylene Cutting Board

Abstract

This study calculated kinetic parameters of Escherichia coli O157:H7 and developed a probabilistic model to estimate growth probabilities of E. coli O157:H7 on polyethylene cutting boards as a function of temperature and time. The surfaces of polyethylene coupons (3×5 cm) were inoculated with E. coli O157:H7 NCCP11142 at 4 Log CFU/cm 2 . The coupons were stored at 13 to 35 o C for 12 h, and cell counts of E. coli O157:H7 were enumerated on McConkey II with sorbitol agar every 2 h. Kinetic parameters (maximum specific growth rate, Log CFU/cm 2 /h; lag phase duration, h; lower asymptote, Log CFU/cm 2 ; upper asymptote, Log CFU/cm 2 ) were calculated with the modified Gompertz model. Of 56 combinations (temperature×time), the combinations that had ≥0.5 Log CFU/cm 2 of bacterial growth were designated with the value of 1, and the combinations that had increases of <0.5 Log CFU/cm 2 were given the value 0. These growth response data were fitted to the logistic regression to develop the model predicting probabilities of E. coli O157:H7 growth. Specific growth rate and growth data showed that E. coli O157:H7 cells were grown at 28-35 o C, but there were no obvious growth of the pathogen below 25 o C. Moreover, the developed probabilistic model showed acceptable performance to calculate growth probability of E. coli O157:H7. Therefore, the results should be useful in determining upper limits of working temperature and time, inhibiting E. coli O157:H7 growth on polyethylene cutting board.

Probabilistic Models to Predict Listeria monocytogenes Growth at Low Concentrations of NaNO2and NaCl in Frankfurters

“…Turbid combinations were scored as 1 (growth) or 0 (no growth). The growth response data were analyzed by logistic regression using SAS ® (Version 9.3; SAS Institute Inc., USA) with the following equation to select significant parameters ( p <0.05) with a stepwise selection method ( Koutsoumanis et al , 2004 ; Lee et al , 2012 ). The selected parameters were then used to produce growth/no growth interfaces of L. monocytogenes at 0.1, 0.5 and 0.9.…”

Model to Predict Growth/No Growth Interfaces of Enterococcus as A Function of NACl and NANO2

“…; Lee et al . ). …”

“…; Lee et al . ). A G/NG model generated using logistic regression analysis of experimental data obtained from various treatment combinations should be appropriate to describe bacterial behavior, especially for predicting boundaries between G/NG of bacteria under various conditions.…”

Probabilistic models to describe the effect of NaNO2 in combination with NaCl on the growth inhibition of Lactobacillus in frankfurters

“…The growth response data were analyzed by logistic regression using SAS ® (Version 9.3; SAS Institute Inc., Cary, NC, USA) to select significant parameters (P b 0.05) using a stepwise selection method. The parameters were used to describe the antimicrobial effect of NaNO 2 in combination with NaCl on Lactobacillus growth by calculating the growth probabilities of Lactobacillus with the following equation (Koutsoumanis, Kendall, & Sofos, 2004;Lee, Suk, Lee, Lee, & Yoon, 2012). Table 2 Estimates of the variables selected from the logistic regression analysis by a stepwise selection method to predict the interfaces between growth and no growth of Lactobacillus at desired probabilities in anaerobic condition.…”