Pickering emulsions with chitosan and macroalgal polyphenols stabilized by layer-by-layer electrostatic deposition

Due to the hydrophilic nature of chitosan, its use as stabilizers in Pickering emulsions requires of hydrophobic modifications that can be achieved by layer-by-layer electrostatic deposition. This study aims to explore and optimize the effects of multiple parameters (chitosan-polyphenol ratio, chitosan concentrations, oil-phase ratios, pH and NaCl concentrations) on the stability of Pickering emulsions stabilized by chitosan and macroalgal polyphenols. The binding mode of chitosan and polyphenols in co-stabilized Pickering emulsions was characterized by Fourier transform infrared spectroscopy (FTIR), confocal scanning laser microscopy (CLSM), scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle. The emulsions had the highest physical stability (95.67 %) and specific surface area (2.21 m²/g) at: chitosan-polyphenol ratio 9.5:1 (w:w), chitosan concentration 0.5 % (w/v), oil-phase ratio 5 % (v/v), pH 6, and NaCl concentration 0 mM. FTIR, CLSM, SEM, and AFM evidenced that chitosan and polyphenols were bound by hydrogen bonds and electrostatic interactions at oil-water interfacial layers of emulsions that had a contact angle of 87.8°, indicating that polyphenols combined with chitosan had better ability to stabilize Pickering emulsions compared to chitosan alone. This study broadens the potential applications of naturally extracted macroalgal polyphenols for the development of Pickering emulsions in nutraceutical and functional food industries.