Insight into Oil-in-Water Emulsions Stabilized by Cross-Linked and Pregelatinized Starches: The Effect of Molecular Structure, Surface Activity and Proton Molecular Dynamics

Effective formation and stabilisation of emulsions while meeting high consumer requirements, including the so-called green label, is still a technological challenge. This is related to the multitude of emulsion destabilization mechanisms and the vastness of methods used to study them, which implies the need to develop an understanding of the phenomena occurring in emulsions. Commercial starch preparations obtained by physical and chemical modification were used to prepare model emulsions that were studied in terms of their stability. Native potato starch was the reference material. The analytical methods used included rheology, low field nuclear magnetic resonance (LF NMR), size exclusion chromatography with triple detection (SEC), and surface/interfacial tension measurements. The results showed that chemical and physical modification improved the functionality of starch in emulsions. This is due to not only chemical but also physical modifications, i.e., pregelatinization causes changes in the molecular structure of starch, including an increase in the molecular weight and the degree of branching. As a consequence, the conformation of starch macromolecules changes, which results in a change of the dynamics of protons in the continuous phase of the emulsion and the thermodynamics of starch adsorption at the water/oil interface.