The Effect of Alginate and κ-Carrageenan on the Stability of Pickering Emulsions Stabilized by Shellac-Based Nanoparticles

We developed highly stable shellac-based emulsions that incorporated alginate (Al) and κ-carrageenan (Kcar), two anionic polysaccharides capable of undergoing in situ crosslinking for various applications. The stability, droplet size distribution, and microstructure of these emulsions were assessed. Fluorescence microscopy confirmed nanoparticle accumulation at the oil–water interface, which enhanced stability. By leveraging the crosslinking potential of the polysaccharides, we created Pickering emulsion hydrogels (PEH) loaded with curcumin, a model food supplement with poor water solubility, and evaluated their release profiles in an in vitro gastrointestinal model. The results demonstrated two distinct release behaviors: full release in the small intestine and targeted release in the large intestine. Further study revealed fundamental differences in how Al and Kcar influence creaming, which led to a deeper investigation into the mechanisms behind these differences. Rheology measurements showed that a more complex mechanism governs the system’s viscosity. Small angle X-ray scattering (SAXS), Fourier transform infrared spectroscopy (FTIR), and further viscosity measurements revealed that hydrogen bonding in the Kcar emulsions formed unique structures, which provided superior resistance to creaming. This study highlights the potential of tailoring emulsion hydrogels for specific applications in food and drug delivery systems and offers new insights into the structural dynamics of biopolymer-stabilized emulsions.