Interaction differences between ionic polysaccharides and egg white proteins dominant the thermal gelation behaviour of proteins

The effects of interaction differences between egg white proteins (EWP) and three polysaccharides with different charge–konjac glucomannan (KGM, neutral polysaccharide), xanthan gum (XG, anionic polysaccharide), and chitosan (CS, cationic polysaccharide) –on the gelation properties of EWP were compared in this study. The addition of both KGM and XG reduced the gel hardness and water holding capacity, while CS addition had no significant effects. Low-field nuclear magnetic resonance analysis proved that immobilized water constituted the main water state in these gel systems since the T 22 accounted for >70% of the total peak area in all samples, but KGM had minimal impact on water distribution when compared to XG and CS. KGM induced the formation of loosely EWP aggregates, XG promoted EWP to form small dense clusters, while CS facilitated the development of large aggregates. It was speculated that interaction differences between proteins and polysaccharides can affect their gelation properties. Results of zeta-potential, turbidity, and fluorescence spectra indicated that little electrostatic interaction formed between EWP and KGM, while strong electrostatic interactions were observed in the EWP-XG and EWP-CS complexes. All of the EWP-polysaccharide complex solutions showed weak structures with shear-thinning behaviour. Interaction differences between EWP and polysaccharides showed different influence on the gel transition temperature of EWP (63.6 °C), which further resulted in the differences in texture profile analysis and water holding capacities of complex gels. This study can offer a theoretical foundation for the strategic selection and development of novel EWP gels.