Maillard-induced pea protein isolate/carboxymethyl chitosan conjugates: Synthesis, characterization, and applications...

To overcome functional limitations of pea protein isolate (PPI), PPI-carboxymethyl chitosan (CMCS) conjugates (PC) were synthesized via controlled Maillard reaction. By adjusting PPI:CMCS mass ratios (2:1, 1:1, 1:2), samples with increasing grafting degrees (GD) (PC₂₁: 17.95 %; PC₁₁: 32.96 %; PC₁₂: 47.51 %) were prepared. SDS-PAGE/FT-IR confirmed covalent conjugation. Secondary structure analysis revealed GD-dependent rigid-to-flexible transition with reduced α-helix/β-sheet and increased β-turn/random coil. Fluorescence redshift with decreased surface hydrophobicity/contact angles indicated enhanced microenvironment hydrophilicity proportional to GD. Emulsifying activity and stability indices increased with GD, peaking at 56.96 m²/g and 218.24 min for PC₁₂. Compared to PPI-stabilized Pickering emulsions, Maillard reaction-induced conjugates yielded smaller particles, enhanced stability, and superior curcumin protection (>75 % retention), with improvements amplifying at higher GD. This demonstrates grafting degree-dependent enhancement of emulsification performance and emulsion functionality, facilitating PPI 's expanded applications in functional foods and delivery systems.