Stabilization of chitosan-based high internal phase emulsions via tannic acid-mediated physical crosslinking

The development of protein-free, food-grade emulsifier to stabilize high internal phase emulsions (HIPEs) presents a significant challenge. Chitosan (CS), an abundant natural polysaccharide, holds great potential for this role. The existing strategies often rely on chemical derivatization of CS, which introduces synthetic complications and undesired non-natural ingredients. To overcome the limitations, we develop a tannic acid-chitosan complex (TACS) emulsifier, enabling the fabrication of food-grade HIPEs. A combination of experimental characterization and molecular dynamics simulations reveals that TA acts as a key physical crosslinker to promote the formation of the TACS interfacial film. This enables the fabrication of stable HIPEs whose morphology and rheological properties can be tailored by varying the TACS concentration, TA-CS ratio, and oil fraction. Furthermore, this TACS-based HIPE provides enhanced protective encapsulation for curcumin and demonstrates potent antioxidant activity. This work establishes a generalizable, non-Pickering polysaccharide-based paradigm for stabilizing HIPEs, offering a promising platform for designing fat substitutes applicable for individuals with protein allergies.