Potassium-regulated LA-GG composite hydrogels as dual-network gelling matrices: gelation mechanism, structural characterization, and application in capsule-based delivery.

The unclear gelation mechanism of K+ in low-acyl gellan gum (LA)-guar gum (GG) hydrogel has hindered their further applications. In the present study, the critical role of K+ concentration in regulating the structure-property relationships of LA-GG composite hydrogels was elucidated. Multiscale characterizations (texture analysis, rheology, zeta potential, density functional theory, etc.) demonstrated that the gelation process of LA-GG was primarily regulated by K+ through electrostatic shielding of the carboxyl groups in LA. An optimal K+ concentration of 0.6% (w/v) maximized the textural properties of the LA-GG gel, yielding a gel strength of 140.83 ± 5.34 g, chewiness of 213.77 ± 11.45 g, and cohesiveness of 0.90 ± 0.04 g, while concurrently enhancing its viscoelasticity. This improvement was attributed to K+-mediated electrostatic screening, which reduced intermolecular repulsion, promoted closer polysaccharide association, and facilitated the formation of a dense and homogeneous hydrogen-bonded network between LA and GG. Conversely, K+ concentrations exceeding 0.6% (w/v) led to charge screening saturation, inducing inhomogeneous aggregation that compromised network uniformity and impaired gel performance. When utilized as capsule matrices, the 0.6% K+-mediated LA-GG gel exhibited superior gastrointestinal stability, with a minimal quercetin leakage of only 10.01% prior to reaching the simulated colon. In vitro digestion confirms its potential for targeted colonic delivery. This work establishes clear structure-function relationships in ion-regulated polysaccharide gels, offering guidance for designing controlled-release carriers for functional food applications.