Effect of ultrasonic amplitude on the general properties of W/O emulsion controlled-release coagulantand the quality enhancement of brine tofu

Abstract Objectives To enhance the quality of tofu produced using brine (MgCl2), this study investigated the effects of an emulsion-controlled-release coagulant (ECRC) prepared through ultrasonic emulsification on the physical and gelation properties of tofu. Materials and methods The ECRC were prepared using different ultrasonic amplitudes. The average particle size, particle size distribution, viscosity, stability, and Mg2+ encapsulation rate were measured to determine the optimal preparation conditions. Then, the Mg2+ controlled-release properties and storage stability of ECRC were measured, and the effects of ECRC on tofu quality were investigated. Results The particle size distribution of the ECRC was uniform when the ultrasonic amplitude was 80%, with an average particle size of 638.12±16.23 nm, excellent emulsion stability, and a Mg2+ encapsulation rate of 51.23%±0.02%. In comparison to MgCl2, the ECRC significantly extended the coagulation time for soybean protein, increasing it from 9.00±0.82 to 28.00±1.00 s. Concurrently, it facilitated the formation of a uniform and dense gel network within the tofu while markedly enhancing its moisture content. The hardness, elasticity, texture, and overall appearance of tofu prepared using ECRC were superior to those of traditional brine coagulant tofu, thereby improving both its physical attributes and textural quality. Conclusions This study demonstrated that employing ultrasonic emulsification in preparing emulsion buffer coagulants effectively prolongs soybean protein gelation time and enhances tofu quality. These findings provide a theoretical foundation for the industrial-scale production of tofu.