Pickering emulsions for intelligent curcumin delivery: Synergistic stabilization by starch nanocrystals and soy...

Starch nanocrystals (SNCs) derived from rice starch were complexed with soybean β-conglycinin (7S) or glycinin (11S) to develop food-grade Pickering emulsifiers for curcumin delivery. The effects of the SNC-to-protein mass ratio on particle structure, interfacial properties, emulsion stability, and gastrointestinal digestion were systematically evaluated. At an SNC-to-protein mass ratio of 1:1, the SNCs-7S and SNCs-11S complexes exhibited the smallest particle sizes of 110 ± 4 and 234 ± 6 nm, respectively. Their three-phase contact angles approached 90°, indicating favorable interfacial wettability. SNCs induced concentration-dependent fluorescence quenching of 7S and 11S, with maximum quenching efficiencies of 61.02 ± 1.41% and 37.51 ± 1.09%, respectively. Raman spectroscopy and molecular docking analyses indicated that complex formation involved rearrangements of the protein secondary structure and hydrogen bonding. All calculated binding energies were below -6.0 kcal/mol, with the lowest value of -6.5 kcal/mol observed for SNCs-11S. Pickering emulsions containing 60% soybean oil exhibited shear-thinning and predominantly elastic behavior (G' > G″). The 1:1 composite systems formed the strongest network structures and exhibited no evident creaming, flocculation, or oiling-off after storage at 4 °C for 30 days. The SNCs-7S emulsion achieved a curcumin encapsulation efficiency (EE) and loading capacity of 90% and 7.5%, respectively, exceeding the corresponding values of 86% and 6.0% obtained for the SNCs-11S emulsion. After intestinal digestion, free fatty acid release from the SNCs-7S and SNCs-11S emulsions reached 46.31 ± 2.71% and 40.68 ± 0.71%, respectively. Overall, the 1:1 SNCs-7S system exhibited the most favorable interfacial assembly, storage stability, curcumin encapsulation, and lipid digestibility.