Underlying mechanism of the microwave non-thermal effect as additional microbial inactivation on Clostridium sporogenes at pasteurization temperature level

Microwave processing can induce non-thermal effects that can inactivate additional levels of microorganisms at pasteurization temperature level (80–100 °C). The objective of this study was to investigate the mechanism behind the non-thermal effects of microwaves on vegetative cells of Clostridium sporogenes. Cell membrane damage were assessed through nuclear fluorescent dyes and by measuring nuclear acid and protein leakage. The results showed that microwave non-thermal effects and conventional water bath treatment resulted in similar nuclear acid leakage. However, microwave non-thermal effects inflicted more severe damage to the cell membranes of Clostridium sporogenes, resulting in increased protein leakage from both the inner of the cell and the cell membrane (A260 = 0.25 vs. 0.18). Consequently, it can be inferred that the inactivation of additional Clostridium sporogenes by microwave non-thermal effects is primarily attributed to the disruption of cell membranes induced by alternating electromagnetic fields, and this phenomenon is further potentiated at elevated temperatures. •Microwave processing caused more microbial lethality due to non-thermal effect.•Microwave non-thermal effect brought more protein leakage than water bath.•No more nuclear acid leaked for microwave non-thermal effect killed cells.•Microwave fields broke more cell membrane and enhanced the permeability.