Novel Blueberry Leaf Polysaccharide–Xanthan Gum Composite Gels for Curcumin Encapsulation: Enhanced Stability and Controlled Release

Curcumin is a natural active ingredient with various health benefits but suffers from poor water solubility, chemical instability, and rapid metabolism. This study developed a novel composite gel, blueberry leaf polysaccharide–xanthan gum (BLP-XG), for the protection and delivery of curcumin. The experimental results demonstrate that the formation of stable composite gel networks is predominantly facilitated by hydrogen bonding and electrostatic interactions between BLP and XG components. In comparison with single-component systems, composite gels exhibit superior structural homogeneity and density, as well as higher thermal stability, viscoelasticity, and predominantly elastic solid behavior. The BLP-XG composite gel achieved the highest curcumin encapsulation rate of 84.23% when the BLP concentration was 2.0%. The composite gel system effectively retained curcumin in the gastric juice and released it in the small intestine. Furthermore, the presence of BLP in the composite gel inhibited curcumin degradation under UV irradiation. This study establishes the research foundation for the development of efficient and stable delivery systems to protect and deliver curcumin and extends the use of blueberry leaf polysaccharides in food and pharmaceutical applications.