Insight into the effects of pulsed electric field on the structure, aggregation characteristics and functional properties of whey proteins

The effects of pulsed electric field (PEF) under different electric field intensities (EFIs, 5-20 kV/cm) and treatment times (2-8 ms) on the structural properties, aggregation/dissociation, and rheological characteristics of whey proteins (WPs) were investigated. An increase of visual turbidity and particle size measurements in 5 and 10 kV/cm PEF treatment groups indicated the formation of larger, insoluble aggregates dominated by disulfide bonds cross-linking and enhanced surface hydrophobicity. However, with the augmentation of EFI reaching a pivotal level (15 and 20 kV/cm), the decrease of hydrophobic interaction coupled with the increased electrostatic repulsion due to increased helix structure can dissociate the aggregates in response to blue-shifted particle size and thin irregular cavern-like structure, causing the solubility increased by 5.24% (20 kV/cm treatment for 8 ms). Furthermore, WPs oxidation played an important role in aggregates disintegration and liberation of peptides due to protein polarization and attack of reactive radicals produced by electrochemical reaction. Rheological analysis showed that higher solubility and diminished particle size after 15 and 20 kV/cm treatments improved the emulsifying capacity and decreased viscosity and interfacial tension of WPs dispersion. Conclusively, structural modification and preeminent functional properties were prompted by the extension of EFI and treatment time. Therefore, an effective theoretical basis may be proposed for PEF used as a promising technology to modify the functional characteristics of WPs.