Effect of 12-HSA Concentration on the Physicochemical Properties, Stability, and Curcumin Bioavailability of Ultrasound-Assisted Enzymatically Glycosylated Casein-Stabilized Oleogel-Structured Emulsions

s To investigate the effects of glycosylated covalent complexes and 12-hydroxystearic acid (12-HSA) on the properties of oleogel-structured high internal phase emulsions (OGHEs), this study prepared OGHEs with varying 12-HSA concentrations (0%, 1%, 3%, 5%, and 7%) using 1.5% sodium caseinate (SC) or conjugates of SC and carboxymethyl chitosan (SC-CMCS) as emulsifiers. A systematic evaluation was conducted on their droplet size, zeta potential, interfacial adsorbed protein content, rheological properties, stability, curcumin encapsulation efficiency, and in vitro digestion performance. Results showed that SC-CMCS-stabilized OGHEs exhibited significantly superior apparent viscosity and elastic modulus (with G' consistently greater than G'') compared to SC-stabilized OGHEs. The elastic modulus (G') reached its maximum at 7% 12-HSA, accompanied by a smaller initial droplet size (8.02 ± 0.17 μm) and more uniform distribution. Confocal laser scanning microscopy (CLSM) revealed a dual-stabilization structure consisting of oil droplets and a fibrous network, while differential scanning calorimetry (DSC) confirmed enhanced thermodynamic stability. Meanwhile, SC-CMCS-stabilized OGHEs with high 12-HSA concentrations demonstrated markedly improved thermal stability, freeze-thaw stability, and lipid oxidation stability. After 28 d of storage, their particle size increased only to 11.88 ± 0.79 μm, and the curcumin encapsulation efficiency significantly rose to 95.85 ± 0.31%, with a retention rate of 96.32 ± 0.38% after 12 d of storage. These results indicate that the synergistic interaction between SC-CMCS and 12-HSA comprehensively enhances the functionality of OGHEs, providing theoretical support for the development of carriers for active ingredients in functional foods.