Modulation of double network assembly via different calcium sources and GDL concentrations for simulating intramuscular fat

Responding to the global demand for low-fat plant-based foods, this study developed soy protein isolate (SPI)-sodium alginate (SA) double-network emulsion gels as fat replacers, using various calcium sources (CaCO₃, CaHPO₄, CaSO₄) and glucono-δ-lactone (GDL) concentrations. The gelation kinetics, mechanical properties, water distribution, and microstructure of the gels were thoroughly characterized. Results indicated that CaCO₃ and CaHPO₄ facilitated a slower release of Ca²⁺, promoting sequential cross-linking that led to homogeneous dual networks stabilized primarily by hydrogen bonds and hydrophobic interactions. These gels showed high water-holding capacity (>90%), tunable elasticity, uniform oil distribution, and improved thermal stability. In contrast, CaSO₄ induced rapid alginate cross-linking, resulting in rigid, heterogeneous networks rich in disulfide bonds, with limited structural recovery. Increased GDL content accelerated gelation but reduced mechanical strength in CaSO₄ gels. The CaHPO₄-GDL system demonstrated outstanding filling performance, with over 45% efficiency in protein matrix integration and minimal surface defects, highlighting its potential as an effective simulated fat. This work offers a feasible strategy for fabricating texture-tunable, plant-based simulated fat through optimized Ca²⁺ and GDL synergy.