Stabilization and functionalization of aqueous foams by Quillaja saponin-coated nanodroplets

Abstract

We report evidence for stabilization and functionalization of aqueous foams stabilized by Quillaja saponin (QS)-coated nanodroplets. In contrast to foams stabilized by QS, stabilized the foams of QS-coated nanodroplets showed superior foamability, stability and multi-functional characteristics. Specifically, the half-life time of the foam stabilized by nanodroplets was approximately 4 times that of saponin. The microstructure observation indicates the nanodroplets from assembly of saponin around oil droplet were strong attachment at the gas-liquid interface and stabling a large gas-liquid interfacial area in a hierarchical structure. The surface dynamic adsorption and large deformation rheology were performed, revealed that QS nanodroplets were almost irreversibly adsorbed at air-liquid interface and exhibited less surface desorption and high elastic-viscous response to a large mechanical deformation. These nanodroplets stabilized foams presented a large capacity for loading hydrophobic flavors and nutrients (e.g., β-carotene and curcumin), which could be used to create a new class of foam food products with sustained release of flavors and/or health benefit functionality.

Keywords: Foam; Functionalization; Interfacial adsorption; Nanoemulsion; Quillaja saponin.