Evaluating continuous nanosecond pulsed electric field (nsPEF) treatment as a non-thermal alternative for human milk pasteurisation

Abstract

This study investigated the application of nanosecond pulsed electric field (nsPEF) treatment as an alternative pasteurisation method for donor human milk (DHM). A 0.1% saline solution was identified as the closest imitation to the received DHM in terms of pulse waveform and conductivity, which was used for the optimisation of PEF parameters. Complete inactivation of inoculated Escherichia coli was achieved after nsPEF treatment in saline with an initial count of 5 log CFU/mL and nearly a 7 log CFU/mL reduction with an 8 log CFU/mL initial count. In DHM, nsPEF treatment resulted in a 3 log CFU/mL reduction with an initial 5 log CFU/mL count and a 5 log CFU/mL reduction at higher initial counts. However, no statistically significant difference in log reduction was observed across various initial bacterial counts in DHM samples. Microscopic analysis revealed potential protective effects of human milk fat globules and epithelial cells on E. coli, resulting in residual counts of 2–3 log CFU/mL post-treatment. Overall, the maximum temperature during nsPEF treatment was approximately 36°C, highlighting its advantage over thermal pasteurisation, and further optimisation could be conducted to evaluate the potential protective effects of the milk components.