Cold‐Set Composite Hydrogels From Chia Seed Protein and Mucilage: Rheological Optimization for Enhanced Curcumin Stability and Controlled Release

This study evaluated the effect of chia seed protein and mucilage concentration (7.5%–15%) on the structure, stability, and release profile of curcumin in cold‐set hydrogels. Increasing the concentration of protein and mucilage led to an improvement in the textural and rheological characteristics of the hydrogels. The highest hardness (1.75 N) was observed in the hydrogel containing 12.5% protein and 12.5% mucilage. As the concentrations increased from 7.5% to 15%, the water‐holding capacity (WHC) significantly decreased ( p < 0.05) from 87% to 58%, which was correlated with a corresponding reduction in swelling capacity. Thermal analysis revealed that increasing the mucilage content enabled the formation of molecular interactions within the hydrogel, thereby enhancing the thermal stability of the structure. The XRD data showed that in the protein and mucilage hydrogels, the mucilage was in an amorphous condition, and the hydrogelation process had no effect on the protein′s XRD pattern. Curcumin loaded into the hydrogel containing 12.5% protein and 12.5% mucilage had better stability than free curcumin during heat and light exposure. The loading amount of curcumin in chia protein isolate and mucilage and encapsulation efficiency were 9.76 ± 0.08 μ g.mg −1 and 90.15 % ± 0.05 % , respectively. The fluorescence findings confirmed the effective loading of curcumin into the hydrophobic core of chia protein isolate and mucilage. The release of curcumin from protein and mucilage gels was affected by the mucilage concentration, such that increasing the mucilage concentration from 7.5% to 12.5%, along with the increase in hardness, caused curcumin release in simulated stomach conditions to decrease from 43.42% to 21.72%. Additionally, adding mucilage to chia protein gels significantly reduced the release rate of curcumin from protein–mucilage composite hydrogels in simulated gastric conditions. The modeling results showed that the Korsmeyer–Peppas model is the most suitable for describing the release behavior under stomach and intestinal conditions (0.95 < R 2 < 0.99). The results indicate that the combined chia protein–mucilage hydrogel, prepared by cold coagulation, can serve as a novel carrier for encapsulating and transporting bioactive compounds, with potential applications in the food and pharmaceutical industries. Considering that chia seed protein was used as a hydrogel, this study showed that protein hydrogels were not generally formed at low concentrations but only at high concentrations. However, the formed hydrogels lacked sufficient strength and exhibited weak structures. These hydrogels were strengthened using chia seed mucilage.