Expansion and Validation of a Predictive Model for the Growth of Bacillus Stearothermophilus in Military Rations

: Predictive models for the exponential growth rate (EGR) and germination, outgrowth, and lag times (GOL) of Bacillus stearothermophilus previously developed in our laboratory were expanded to include higher salt (1.5%) formulations. The expanded models were validated in 7 military meals-ready-to-eat incubated at temperatures from 45 °C to 60 °C, and tryptic soy broth incubated from 37.5 °C to 70 °C. The 95% prediction intervals for EGR were fail-safe in all the military rations tested. The 95% prediction intervals for GOL were failsafe in 5 of the 7 rations. The TSB results illustrate the dangers of using empirical models to predict microbial behavior outside the range of conditions under which the models were developed.

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