Impact of urea on the microstructure of commercial canola protein-carrageenan network: a research note

Biopolymer mixtures contribute to network formation in food systems. The effects of pH and urea on the structural ordering of canola protein isolate-kappa-carrageenan (CPI-kappa-CAR) gels were assessed using scanning electron microscopy (SEM). At pH 6, loosely-crosslinked CPI networks with large empty pores were produced whereas tightly-crosslinked structures were displayed at pH 10. The structure of CPI network was greatly improved when CPI and kappa-CAR were mixed, indicating a synergistic behaviour between the two macromolecules. Urea affected the structural arrangement and interactions involved in the formation CPI-kappa-CAR gels. Urea-treated gels showed excessive network disruption and breakdown. The microstructural results support the involvement of disulfide bonds and noncovalent interactions in the structural arrangement of CPI-kappa-CAR networks.