Exploiting tea protein-chitosan nanoparticles stabilized Pickering emulsion to enhance the bioaccessibility of curcumin.

Natural biopolymer-based nanoparticles are promising candidates for emulsion stabilization and delivery of hydrophobic compounds. In this study, tea protein (TP) and chitosan (CS) were employed to fabricate complex nanoparticles (NPs) using a pH-dependent method. At a mass ratio of 2:1 (TP:CS), the NPs exhibited favorable properties (206.62 nm, -30.86 mV, 85.41° contact angle) owing to electrostatic interactions, hydrogen bonding, and hydrophobic interactions (binding energy of the complex was -5.40 kcal/mol). At a particle concentration of 2 % and an oil-phase volume fraction of 60 %, the Pickering emulsion stabilized by TP-CS2:1 NPs remained physically stable. Compared with TP alone, TP-CS2:1 NPs significantly enhanced the encapsulation efficiency and antioxidant capacity (DPPH/ABTS) of curcumin (Cur). In vitro digestion confirmed that the emulsions reduced gastric degradation of Cur, increasing its bioaccessibility by 17.4 %. Accordingly, this study provides a strategy for designing natural protein-polysaccharide NPs for functional emulsions and sustained delivery systems.