Response of Bacillus cereus spores to high hydrostatic pressure and moderate heat

The effects of high pressure (400–600 MPa) and moderate heat (60–80 °C) treatments at various process times (10–20 min) on the reduction of Bacillus cereus   As 1.1846 spores, suspended in milk buffer were investigated. In the present work, response surface methodology (RSM) was employed, and a quadratic equation of high hydrostatic pressure inactivation was built with RSM. By analyzing response surface plots and corresponding contour plots and by solving the quadratic equation, experimental values were shown to be significantly in agreement with predicted values, since the adjusted determination coefficient (RAdj2) was 0.9752 and the level of significance was P < 0.0001. Optimum process parameters for a six-log cycle reduction of B. cereus spores were obtained: pressure, 540.0 MPa; temperature, 71 °C; and pressure-holding time, 16.8 min. The adequacy of the model equation in predicting optimum response values was verified effectively using experimental test data that was not used in the development of the model.