Pulsed electric fields-mediated inactivation of foodborne pathogens in bovine colostrum

Abstract

Bovine colostrum exhibits promising immunological properties, but the degradation of immunoglobulins during conventional thermal pasteurization limits its widespread use. Pulsed electric fields (PEF) processing, with its minimal thermal effect, is a promising alternative pasteurization technology. This study explored the potential of using PEF processing to inactivate bacteria in bovine colostrum. The effect of continuous flow PEF on the inactivation of naturally occurring bacteria in early (0-48 h lactation) and late (≤7 d lactation) stage colostrum was tested. Preheating to 45 °C combined with PEF treatment (~13 kV/cm, 229-239 kJ/L) resulted in a > 5-log reduction in microbial numbers for both conditions. Next, the feasibility of using PEF to inactivate surrogate non-pathogenic organisms, Escherichia coli ATCC 25922 and Listeria innocua, was investigated. Following 40 °C pre-heating and PEF treatment (11 kV/cm, 209 kJ/L), a 5-log reduction was achieved, though L. innocua appeared less sensitive to PEF treatment. Finally, the effect of PEF on pathogenic bacteria was explored in batch mode, where samples were contained within cuvettes. Colostrum was inoculated with two cocktails of either three pathogenic E. coli or five L. monocytogenes strains. At a field strength of 8 kV/cm and pre-heating to 40 °C, maximum specific energies of 184 and 175 kJ/kg resulted in 4- and 2.4-log reductions in E. coli and L. monocytogenes, respectively, further supporting the different sensitivities of bacteria to PEF treatment. Based on current knowledge, this is the first study to demonstrate the feasibility of PEF as an alternative pasteurization technology for colostrum.

Keywords

Pulsed electric fields / Escherichia coli / Listeria monocytogenes / Listeria innocua / Bovine colostrum / Novel pasteurization.

Ethical statements

Not applicable.

Author contributions

The authors confirm contribution to the paper as follows: study conception and design: Pletzer D, Bremer P, Oey I; data collection: King J, Hardie Boys MT, Oey I; analysis and interpretation of results: King J, Oey I; draft manuscript preparation: King J, Hardie Boys M, Pletzer D, Chen C, Finer J, Fung L, Bremer P, Oey I. All authors reviewed the results and approved the final version of the manuscript.

Data availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Acknowledgments

This work was funded by NIG Nutritionals and Callaghan Innovation. The authors would also like to thank Ian Ross, Nicholas Horlacher, and Michelle Petri for their technical assistance.

Conflict of interest

The authors declare that they have no conflict of interest. This work was funded by NIG Nutritionals which sells nutritional formulations, including bovine colostrum. Finer J, Chen C, and Fung L work for NIG Nutritionals and were involved in the editing of this manuscript. However, they were not involved in designing the experiment, nor were they involved in the collection, analysis, presentation, or interpretation of the data described in the manuscript.

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