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

- 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.

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.

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