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Pulsed electric fields (PEF) can cause irreversible damage to the bio-membranes of microorganisms, with the resulting electro-mechanical stresses induced across their membranes stretching and potentially rupturing these phospholipid bi-layers. The electro-mechanical stresses have an electrostrictional nature, as the membrane the cytoplasm inside the membrane and the external suspension have different dielectric and electrical properties. .
PEF treatment is typically considered non-thermal because the direct effect of the forces due to the external electric field do not cause increases in the global temperature of the microbial liquid suspension. However, other factors, such as localised heating of the membrane, may potentially contribute to membrane damage.
Analysis of this local heating effect is important for further understanding of the biological action of the externally-applied electric field as potentially the local heating may play non-negligible role in the PEF inactivation process.
This paper presents an investigation of the transient local heating and transient stresses induced across bio-membranes of model microorganisms, stressed with an external electric field. A model of the PEF process was developed and studied using COMSOL Multiphysics software. The obtained results demonstrate that high-field impulses can result in the development of strong local thermal stresses across the membrane and significant local over-heating of the membrane and cell wall, as compared with the global temperature of the external suspension. Thus, the obtained results demonstrate that, even in the case of globally “non-thermal” PEF treatment, when the temperature of the suspension remains below the thermal inactivation threshold, local hot spots can be developed, which may result in further damage to the bio-membrane. The developed model can aid in further understanding the biological action of impulsive electric fields, and in further development and optimisation of PEF technology and its practical bio-medical, environmental and other applications.
