Calcium salt-induced rice starch-soybean protein composite gels: Mechanism of influence of calcium salt type and concentration on gel properties

The study examines how different concentrations of calcium citrate (CCI), calcium carbonate (CCA), calcium gluconate (CGL) and calcium chloride (CCH) affect the gelling properties of rice starch-soybean protein composites and calcium bioaccessibility. Results showed CCI and CCA had weaker shielding effects on electrostatic repulsion than CGL and CCH, as they increased the pH while CGL and CCH decreased it. CCI and CCA promoted protein β-sheet structures and enhanced starch crystallinity, facilitating bicontinuous and packed networks, respectively. CGL and CCH induced protein β-turn structures and enhanced starch crystallinity, facilitating disordered aggregation networks. Gels with CCI and CCA have superior properties, while those with CGL and CCH are inferior. The gel with 30 mmol CCA has the highest strength (102.8 g) and water-holding capacity (94.6 %), while that with 30 mmol CCH has the lowest (17.1 g and 84.9 %). CCI exhibits the highest bioaccessibility. These results guide calcium-containing texture-modified food design.