Designing Gastric-Stable Adsorption Layers by Whey Protein-Pectin Complexation at the Oil-Water Interface

This work aims to design gastric-stable emulsions with food-grade biopolymers using a novel multiscale approach. The adsorption layer formation at the oil-water interface was based on opposite charge interactions between whey proteins and pectin (with different esterification levels) at pH 3.0 by a sequential adsorption method. The interfacial assembly and disassembly (interfacial complexation, proteolysis, lipolysis) during in vitro gastric digestion were evaluated using a quartz crystal microbalance with dissipation monitoring, zeta-potential, dynamic interfacial tension, and interfacial dilatational rheology. Besides, the evolution of the particle size and microstructure of bulk emulsions during the digestion was investigated by static light scattering and light microscopy. Compared with whey protein isolate (WPI)-stabilized emulsions, the presence of an additional pectin layer can prevent or at least largely delay gastric destabilization (giving rise to coalescence or/and oiling off). Especially, the esterification degree of the pectin used was found to largely affect the emulsion stability upon gastric digestion.

Automated summary

This study aims to design gastric-stable emulsions using a novel approach with food-grade biopolymers. By utilizing opposite charge interactions between whey proteins and pectin, an adsorption layer is formed at the oil-water interface. The stability of the emulsion during gastric digestion is evaluated through various methods, including quartz crystal microbalance, zeta-potential, dynamic interfacial tension, and interfacial rheology. The presence of an additional pectin layer is found to significantly improve the emulsion stability, and the esterification degree of the pectin plays a crucial role in the digestion process.