From molecular interactions to macroscopic functions: Dynamic cross-linked carboxymethyl cellulose as a strategic...

To enhance the physicochemical and emulsifying properties of soy protein isolate (SPI), carboxymethyl cellulose (CMC) with different crosslinking degrees was combined with SPI to form composite systems at pH 4 and 7. The dissolution and aggregation behaviors were evaluated by solubility, surface hydrophobicity and zeta potential. Structural properties were revealed by FT-IR and SEM. The physicochemical properties and structural of SPI-CMC emulsion were evaluated through emulsifying properties and rheological properties. The results showed that, CMC effectively reduced SPI aggregation at pH 4 and enhanced its solubility and stability through electrostatic attraction. SPI and CMC carried negative charges at pH 7. Electrostatic repulsion dominated their interaction, and the suppression of SPI aggregation was limited; From the perspective of different crosslinking degrees, moderately cross-linked CMC enhanced the interaction SPI-CMC, promoted the formation of hydrogen bonds in the SPI-CMC, ensured uniform emulsion distribution, demonstrating excellent emulsifying activity and stability. Excessively cross-linked CMC damaged its structure. The emulsion underwent phase separation and water distribution, resulting in a decrease in emulsifying properties. The results showed that the moderately cross-linked CMC can effectively enhance the solubility and emulsifying properties of SPI, providing a practical formulation strategy for stable plant-based acidic beverages during the shelf life.