Regulatory Mechanism of Degree of Esterification and Molecular Mass on the Emulsifying Performance of Pectin

To investigate the regulatory mechanisms of the degree of esterification and molecular mass on the emulsifying properties of pectin, this study analyzed the aggregation behavior, aggregate structure, interfacial properties, emulsifying properties, and the structure of the adsorption layer at the interface of pectins with different structures. The results showed that: 1) as the degree of esterification increased from 35% to 73%, the size of pectin aggregates decreased regularly from 1950 to 1443 nm, the polarity of hydrophobic microdomains in the aggregates decreased, the diffusion rate to the oil-water interface increased significantly, the amount of pectin adsorbed onto the interface increased from 54.4 to 95.9 ng/cm², the interfacial adsorption layer thickness decreased from 76.9 to 43.6 nm, the equilibrium interfacial tension decreased from 24 to 18 mN/m, and the emulsifying performance was significantly improved; 2) as the molecular mass increased from 0.55 × 10⁵ to 1.30 × 10⁵ Da, the size of pectin aggregates increased from 1195 to 1443 nm, the diffusion rate to the oil-water interface decreased, the interfacial adsorption amount decreased from 127.3 to 95.9 ng/cm², and both the interfacial and emulsifying properties deteriorated. However, since the internal hydrophobicity of the aggregates increased, the desorption of pectin from the interface was inhibited, thereby improving the emulsion stability during storage. The findings of this study provide a theoretical basis for the development and utilization of pectin emulsifiers.