Mathematical model for the combined effect of temperature and pH on the thermal resistance of Bacillus stearothermophilus and Clostridium sporogenes spores.

Two mathematical models have been studied to establish the relationship between the pH, treatment temperature and thermal destruction constant (k) of Bacillus stearothermophilus and Clostridium sporogenes spores. The study was carried out by heating the spores in mushroom extract acidified with two different acidulants (citric acid and glucono-delta-lactone). Among the models studied, the one that best described the inactivation was a second order polynomial equation, the precision of which depended on the microorganism studied.