Microgelation imparts emulsifying ability to surface-inactive polysaccharides-bottom-up vs top-down approaches.

In order to impart emulsifying ability to gel-forming polysaccharides that have not been used as emulsifying agents, three kinds of polysaccharides, agar, curdlan, and gellan gum were converted to microgels by different gelation methods via the bottom-up and top-down approaches. We clearly demonstrated that agar and curdlan acquired the ability to emulsify an edible oil by microgel formation. Among the colloidal properties of microgel suspensions such as microstructure, particle size, zeta-potential, viscosity, and surface hydrophobicity, we pointed out the importance of particle size on the emulsifying ability of polysaccharide-based microgels. The creaming behavior of the microgel-stabilized emulsions depended on the polysaccharide types and microgel preparation methods. The emulsion stability against oil droplet coalescence was extremely high for agar and curdlan microgel-stabilized emulsions during storage in the static condition, whereas different stability was observed for both the emulsions, that is, the curdlan microgel-based ones were more resistant to dynamic forcible destabilization by centrifugation than the agar ones, which can be attributed to the surface hydrophobicity of the microgels.