Abstract:This study utilized the electrostatic interaction between soy protein isolate （SPI） and pectin to inhibit the thermal aggregation of proteins，thereby achieving the regulation of the thermal gel strength and rheological properties of SPI. Firstly，the pH range of4.2 to 5.5 was determined as the optimal for the formation of a stable electrostatic complex between SPI and pectin through Zeta potential measurement. Subsequently，the optimal pectin addition amount was identified as 2.0% to 2.5% based on the stability and morphology of the complex before and after heating. The electrostatic interaction between SPI and pectin led to a flowable thermal gel of SPI. The elastic modulus，apparent shear viscosity，and yield stress of the gel all increased with the increase in pH value. Additionally，according to the framework established by the International Dysphagia Diet Standardization Initiative （IDDSI），the thermal gels formed by the SPI-pectin complex at pH4.2to4.6 were all classified as texture level2，while the thermal gel formed at pH5.5 was classified as texture level 3. These findings provide novel approaches for developing high-protein，easy-to-consume fluid diets tailored to elderly individuals with varying degrees of dysphagia.