Optimized complex coacervation and tailored cross-linking of faba protein–xanthan gum complexes for enhanced structural stability and emulsifying performance

This study examined the complex coacervation between faba protein isolate (FPI) and xanthan gum (XG), focusing on the effects of pH and FPI/XG mixing ratios. Turbidity, zeta potential, and coacervation yield analyses identified pH 4 and a 10:1 mixing ratio as the optimal conditions. The impacts of cross-linking through the Maillard reaction (MR, 3–5 h) and tannic acid (TA, 0.1–0.5 %) were also evaluated. TA treatments produced coacervates with higher surface charge and yield, as well as smaller and more uniform particles compared with MR-treated samples. Structural analyses (FTIR, XRD, and CD) showed a reduction in α-helix content and an increase in amorphous character, while TGA indicated improved thermal stability, particularly in TA-treated samples. Both MR and TA modifications enhanced solubility, surface hydrophobicity, and emulsifying activity; however, TA provided superior emulsifying stability. Molecular docking further confirmed stronger TA-mediated interactions. Overall, both cross-linking strategies improved the structural and functional properties of FPI–XG coacervates, with TA demonstrating greater efficiency in producing stable, high-performance emulsifiers suitable for clean-label food formulations.