Analysis of temperature-dependent bacterial dielectric properties for effective PEF pasteurization

Le résumé fourni par la source

Pre-heating enhances the bactericidal efficacy of pulsed electric field (PEF) treatment. This study provides a solid foundation for optimizing the temperature history of pre-heating for the PEF pasteurization. The capacitance and conductance of the suspensions of Enterobacter hormaechei were analyzed as the temperature increased and decreased. In addition, the membrane permeability after heating and cooling was examined to verify the impedance analysis. Furthermore, the viability of bacteria after the application of PEF (20 kV/cm, 2 μs, 5 times) after heating and cooling was investigated to discuss its relevance to the membrane properties obtained from the impedance analysis. The results indicated that the capacitance of the bacterial suspension increased as the temperature increased from 25 to 45 °C; at ≥ 47 °C, the capacitance decreased and the conductance increased simultaneously. At the maximum temperature of ≤ 45 °C, the change in the bacterial membrane property was reversible, whereas, at ≥ 50 °C, the bacterial membrane was irreversibly denatured. For PEF treatment, the higher the treatment temperature, the stronger the bactericidal effect. Cooling after pre-heating can affect the bactericidal effect, with a significant decrease at ≤ 45 C and only a slight decrease at > 50 °C, where irreversible denaturation occurs.

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