Self-assembly of phycocyanin-nanochitin complexes for antioxidant Pickering emulsions

This study developed a Pickering stabilizer based on polyelectrolyte complexes (PECs) of phycocyanin (PC) and nanochitin (NCh), in order to combine the antioxidant functionality of PC with the nanofibrillar structural support of NCh. At an optimal 1:4 mass ratio, enthalpy-driven complexation yielded a unique "bead-on-string" nanostructure, which resulted in an optimal three-phase contact angle of 80.63 ± 1.29° and facilitated the formation of a thick, viscoelastic interfacial film, as revealed by QCM-D. The complexes exhibited a dual-stabilization mechanism, combining interfacial film reinforcement (dominated by PC) and 3D network confinement (dominated by NCh). Furthermore, simply tuning the overall concentration of these complexes allowed for precise and continuous control over the macroscopic emulsion state, producing systems ranging from fluid emulsions (0.1-0.3%) and gel-like states (0.5-0.7%) to self-supporting gels (1.0-1.5%), all of which drastically outperformed the physical stability of the individual biopolymer controls. Moreover, relative to NCh-stabilized emulsions at the same concentration, PC-NCh-stabilized emulsions exhibited reduced accumulation of lipid hydroperoxides (POV) and thiobarbituric acid reactive substances (TBARS) during 14 d storage at 30 °C, indicating enhanced oxidative stability. These results provide a basis for the design of multifunctional protein-polysaccharide Pickering stabilizers.