Modelling the effect of the redox potential and pH of heating media on Listeria monocytogenes heat resistance

摘要

Study the effect of redox potential and pH of the heating media on Listeria monocytogenes heat resistance and model its action at fixed temperature. The heat resistance of Listeria monocytogenes at 58pC was studied in Brain Heart Infusion broth as a function of pH (from 5p"0 to 7p"0) and redox potential (Eh). The media redox was adjusted with nitrogen gas, potassium ferricyanide and dithiothreitol. A Weibull model was used to fit survival curves. The heat resistance parameter (tpC) was estimated from each inactivation curve. A major effect of pH was observed. Bigelow model was used to describe the effect of redox potential on the apparent L. monocytogenes heat resistance. The highest tpC values have been obtained at pH 7p"0 and oxidizing conditions. The developed model indicates that the Eh has a significant effect and varied depending on the pH of the heating media. The zredox values, calculated from tpC allowed quantifying the influence of heating media redox potential on L. monocytogenes thermal inactivation. The obtained model shows the action of redox potential on L. monocytogenes thermal destruction and might be useful to take into account in food thermal processes.