Effects of pulsed electric fields processing on stability of egg white proteins

Colloidal properties, protein oxidation and electrophoresis patterns were used to investigate the changes of egg white solution during Pulsed Electric Field (PEP) processing. Treatment at electric field strength of 25 kV/cm for 400 mu s did not change the protein solution colloidal properties, including soluble protein content, Z-average size, PDI (polydispersity index) and zeta potential. However, when the processing time exceeded 600 mu s, accompany with a small peak of large particle size appeared, a decrease in soluble protein content (7.84%) and an increase in Z-average size (36.9%) was observed. A slight increase in free sulfhydryl content and no increase in protein carbonyl content detected during PEF treatments. This reflected that protein oxidation did not occur during all treatments but partial protein unfolding or SH ionization was enhanced. Electrophoresis patterns showed insoluble aggregates resulting from covalent and non-covalent binding between heterogeneous proteins. The main components of the insoluble aggregates were lysozyme, ovalbumin and ovotransferrin. (C) 2014 Elsevier Ltd. All rights reserved.