Rheological approaches as a tool for the development and stability behaviour of protein-stabilized emulsions

Emulsion stability is the primary requirement for the industrial applications of many commercial food products. This work analyses the importance of rheology on the characterisation of protein-adsorbed systems, from complex fluid-fluid interfaces to bulk emulsions, as well as their relationship to the stability behaviour of the final emulsion. To accomplish this aim, three case studies involving protein-adsorbed systems at different scales are discussed: bulk rheological properties of protein-stabilized emulsions, interfacial rheology of proteins adsorbed at O/W interface, and the links between interfacial and bulk rheology of proteins/polysaccharide mixtures. The knowledge of the interfacial behaviour on a nanoscale is essential for the development of optimal properties on both the microscale (droplet size distributions and microstructure) and the macroscale (bulk rheology and stability). This work presents linear and nonlinear rheology of complex interfaces, including a discussion on recent progress available for analysing and modelling nonlinear interfacial rheology data. In addition, a similar rheological analysis for protein-stabilized emulsions is reviewed, with the aim of exploring possible links between interfacial shear rheology and emulsion rheology, as well as their connections to emulsion microstructural parameters and emulsion stability. This approach, which mainly relies on the characterization of the interface, might be regarded as very useful to tailor interfaces for the development of optimal emulsion microstructure and stability.