Comparison of Predictive Models for Bacterial Spore Population Resources to Sterilization Temperatures

Abstract

Comparisons of characteristics of recent models and the conventional model of bacterial spore populations during thermal sterilization showed the conventional model was inadequate for general representation because it lacks activation of dormant spores. New models accounting for activation differed in other assumptions but obviated heat shock of indicator spores required when using the conventional model in validations of thermal sterilization. Comparisons of rate constants and simulated and experimental responses of models of B. stearothermophilus spores in constant and dynamic temperatures showed one new model was more general, more accurate and preferred. Arrhenius equations accurately described temperature dependencies of all rate constants of that model.

Evaluation of a Stochastic Inactivation Model for Heat-Activated Spores of Bacillus spp

“…As shown in Fig. 10, the model can produce semilogarithmic survival curves with an activation shoulder, which are visually very similar to those reported in the literature, for example, by Sapru et al (25), which are shown in Fig. 2.…”

“…Peleg (18,20) and van Boekel (33,35) have shown that none of the above assumptions was necessary and that the same survival data on Bacillus stearothermophilus reported by Sapru et al (25) and other investigators (5) can be described by different kinds of alternative four-parameter empirical models, which have a slightly better fit. This was evident not only visually ( Fig.…”

“…The most publicized model of the simultaneous heat activation and inactivation of Bacillus spores in food is that proposed by Sapru et al (24,25), which is an improved version of models proposed earlier by Shull et al (29) and Rodriguez et al (23). All of these authors and others (1,17) assumed that the activation of dormant spores follows first-order kinetics and so does their inactivation before and after activation.…”

“…The most publicized model of the simultaneous heat activation and inactivation of Bacillus spores in food is that proposed by Sapru et al (24,25), which is an improved version of models proposed earlier by Shull et al. (29) and Rodriguez et al (23).…”

Thermal Inactivation of Geobacillus Stearothermophilus Spores Under Sterilization Process

“…Nieliniowy przebieg krzywych śmierci cieplnej przetrwalników jest wynikiem obecności w ich populacji osobników o różnej wrażliwości cieplnej. Z badań własnych [3], jak i innych autorów [10] wiadomo, że w takim przypadku przebieg krzywych przeżycia zależy od początkowego stężenia przetrwalników będących w określonym stanie fizjologicznym (udziału spor zaktywowanych, uśpionych i "głęboko" uśpionych) oraz szybkości procesów aktywacji spor uśpionych i "głęboko" uśpionych, a także destrukcji spor zaktywowanych.…”