Emulsion gels formed by complexation or phase-separation using Artemisia sphaerocephala Krasch. Polysaccharide/whey protein isolate fibrils: Fabrication and applications

The conformational changes resulting from the intermolecular electrostatic repulsion or attraction between charged protein and polysaccharide molecules can be used to create specific structures in foods. In this study, the complex emulsion gels (CEGs) and phase-separated emulsion gels (PEGs) were fabricated using Artemisia sphaerocephala Krasch polysaccharides (ASKPs) and whey protein isolate fibrils (WPIFs) based on the different intermolecular electrostatic assembly modes. The structural, physicochemical, and gastrointestinal properties of these emulsion gels were then investigated. The CEGs were prepared at pH 4.0 to induce the formation of soluble electrostatic complexes between oppositely charged proteins and polysaccharides, while PEGs were fabricated at pH 7.0 to promote phase separation through electrostatic repulsion between similarly charged biopolymers. The PEGs had an O/W1/W2 structure, with the oil droplets being dispersed in a protein-rich phase, which was itself dispersed in a polysaccharide-rich continuous phase. Within the oxidation transition from Fe2+ to Fe3+, CEGs were fabricated with a semi-interpenetrating network in which the WPIF was interspersed into the ASKP-Fe3+ network. PEGs were fabricated with a laminar network structure with a WPIF-Fe2+ inner layer, ASKP-Fe3+ outer layer. A simulated gastrointestinal study showed that the semi-interpenetrating network of CEGs remained structurally intact in gastric fluid but gradually swelled and released Fe3+ and fatty acids in intestinal fluid. While the lamellar network of PEGs disintegrated more rapidly under intestinal conditions, resulting in a higher release rate. This research has shown that novel emulsion gels can be created and may have a range of applications in the food and other industries.