Ultrasonic Treatment of Soybean Protein Isolate: Unveiling the Mechanisms for Gel Functional Improvement and Application in Chiba Tofu

Soybean protein isolate (SPI) cannot meet the needs of modern food production due to various shortcomings. By change of its structural characteristics, its application in the food field may be increased. This study explored the impact of ultrasonic treatment on the structural and gelation properties of the SPI dispersions. By subjecting SPI to ultrasonic treatment at 0-800 W for 10 min, it was found that this treatment significantly reduced the particle size of SPI to 196 nm and caused an increase in its solubility, surface hydrophobicity, and sulfhydryl content as well as significant changes in the protein structure. At an optimal ultrasonic power of 200 W, SPI gels demonstrated an enhanced gelling ability, strength, and water-holding capacity, forming a more uniform and compact structure. Application in Chiba tofu showed that water retention, elasticity, and sensory quality were optimized at 200 W. The findings highlight that a sonication power of 200 W significantly improves the physicochemical and structural properties of SPI, resulting in a denser and more functional gel suitable for Chiba tofu production.