Effect of fish gelatin-gum arabic interactions on structural and functional properties of concentrated emulsions

Concentrated emulsions containing both proteins and polysaccharides are the basis for many commercial products; however, the effects of protein–polysaccharide interactions on the functional properties of these complex systems are often poorly understood from a fundamental standpoint. Hence, the objective of this study was to determine the effects of fish gelatin (FG)-gum arabic (GA) complexation at different aqueous phase pH (3.6, 5.0, and 9.0) on concentrated emulsion structure–function relationships. Concentrated emulsions were prepared using FG-GA mixtures and characterized by rheometry and confocal scanning laser microscopy (CSLM). CSLM images showed that all samples were O/W emulsions; emulsions with lower pH showed smaller oil droplets, greater homogeneity in size distribution, and higher stability. This was attributed to an increased number of FG-GA complexes in the emulsification. Electrostatic attractive interactions and charge neutralization created biopolymer associations with increased emulsification capacity. Samples with FG-GA mixtures at lower pH showed higher elastic moduli under small deformation and exhibited greater deviation between apparent and complex viscosities under the Cox-Merz rule, indicating increased gel network extension and greater intermolecular connectivity between adsorbed layers of adjacent oil droplets. These results can be used to incorporate protein–polysaccharide complexes as a suitable emulsifier in materials comprising concentrated emulsions. [Display omitted] •Biopolymer complexation and charge neutralization induced more emulsion stability.•Emulsions with insoluble complexes had smaller, more flocculated droplets.•Emulsion rheological properties were highly dependent on biopolymer associations.•Emulsions with insoluble complexes had more structured and elastic gel structures.•Associative interactions had improved biopolymer emulsifying ability.