The aim of this study was to model the inactivation of Bacillus coagulans vegetative cells subjected to thermal processing (60–90 °C, 1–30 min) and pulsed electric fields (PEF) (11, 15, and 20 kV/cm, up to 0.12 s, 20 Hz, 15 μs pulse width) at different pH environments (4.0 to 7.0) and in real food matrices (peach puree and carrot juice). Microbial survival data were successfully described using the Gompertz model. Thermal experiments confirmed the high heat resistance of B. coagulans, with maximum survival observed at pH 5.0–6.0. PEF treatments were effective in inactivating vegetative cells, with more intense PEF conditions leading to faster inactivation. Complete inactivation was achieved in less than 15 ms at low pH (4.5), while more than 120 ms was required at pH 6.0. Preheating samples to 50–60 °C prior to PEF significantly reduced the PEF processing time needed for full inactivation, by approximately 88%. In food matrices, the inactivation rate in peach puree was twice as high as in carrot juice, but up to 8 times lower than in buffer solutions. Cells were inactivated twice as fast in peach puree as in carrot juice. This study provides quantitative technical parameter references for optimizing non-thermal processing technologies for acidic/weakly acidic fruit and vegetable products.
Andreou et al. (Sat,) studied this question.