Effect of pulsed electric field parameters on peptide migration selectivity and efficiency in whey protein hydrolysate separation by electrodialysis with ultrafiltration membrane

In this study, we investigated the influence of pulsed electric field (PEF) conditions during electrodialysis with ultrafiltration membrane (EDUF) on the separation of peptides present in a whey protein hydrolysate (WPH). Six PEF conditions, defined by different pulse/pause durations (1s/1s, 5s/1s, 5s/5s, 10s/1s, 10s/5s, 10s/10s) were compared. Peptide migration efficiency (MR charge ) and selectivity were evaluated in both cationic and anionic recovery compartments. The duty cycle (pulse duration divided by total cycle time) emerged as a key parameter, with lower values consistently associated with higher peptide migration efficiency. These effects arise from the combined action of concentration polarization (CP) relaxation during pauses and short-lived electroconvective vortices (ECVs) generated at the start of each pulse. Furthermore, PEF conditions affected peptide selectivity, likely due to the dynamic competition among charged peptides within the diffusion boundary layer (DBL), since repeated pulse-pause cycles affect DBL extension and concentration profile formation, favoring the transport of larger or less mobile peptides. Altogether, these results provide new insights into how mechanisms well established in conventional electrodialysis (ED) also govern peptide transport in EDUF and that tuning the duty cycle can strategically improve both migration efficiency and peptide selectivity.