A sodium alginate-dual-protein double-network gel based on whey protein isolate and Tiger nut protein: Preparation, characterization and its sustained release properties of curcumin

This study developed a sodium alginate-tiger nut protein/whey protein isolate double-network gel, and its sustained-release properties for curcumin were investigated. A series of sodium alginate (SA) concentrations (0-0.3%) were screened, and 0.25% SA was determined as the optimal level, which yielded superior gel hardness (401.67 ± 16.04 g) and water-holding capacity (81.49 ± 1.96%). Structural characterizations verified a double-network structure formation: one relied on protein aggregation, while the secondary network was formed via calcium ions-mediated cross-linking of SA. Owing to the dual-crosslinked network structure, the optimized gel containing 0.25% SA achieved a high curcumin encapsulation efficiency of 93.08 ± 3.05%, and improved the stability of encapsulated curcumin against light, heat, and long-term storage. In vitro gastrointestinal digestion tests demonstrated that the composite gel effectively shielded curcumin from gastric degradation and realized sustained intestinal release. This double network gel exhibits great promise as a carrier for bioactive compound delivery.