Modulating Magnesium Ion Release for Dual Enhancement of Gel Properties and Nutrient Retention in Selenium-Enriched Tofu

Traditional rapid coagulation processes often compromise the quality of selenium-enriched tofu, leading to suboptimal texture and substantial nutrient loss. This study regulated the gel properties and nutrient retention of selenium-enriched tofu by controlling magnesium ion (Mg2+) release from a water-in-oil (W/O) emulsion coagulant through shear rate adjustment (6000–12,000 r/min). The results demonstrated that at the optimal shear rate of 8000 r/min, sustained Mg2+ release facilitated the formation of a homogeneous and dense microstructure accompanied by significantly increased β-sheet content. Compared with conventional methods, the resulting tofu exhibited significant improvements in resilience (increased from 38.73% to 42.54%), water-holding capacity, and nutrient retention, with the selenium content rising from 44.42% to 54.57%. Conversely, deviations from this optimal condition produced either mechanically weak gels or structurally compromised networks with reduced nutrient retention capacity. This study establishes the regulation of shear rate to control Mg2+ release rate as an effective strategy for producing premium selenium-enriched tofu with synchronized optimization of texture and nutritional value, providing new insights for improving the overall quality of functional plant-based protein gels.