Effects of flaxseed gum on the physicochemical properties of wheat starch

Flaxseed gum (FG), with excellent water retention and emulsifying properties, can improve the poor thermal stability and retrogradation of wheat starch (WS) in food processing. This study investigated the effects of different FG mass fractions (0.1, 0.3, 0.5, 0.7, and 0.9 wt%) on the pasting, texture, rheological properties, solubility, swelling power, amylose leaching, and microstructure of WS. FG addition lowered the gelatinization temperature from 94.48 to 69.33 °C and increased the peak viscosity and setback value, promoting starch gelatinization and short-term retrogradation. Solubility, swelling power, and amylose leaching all increased significantly, indicating that FG facilitated water penetration and starch gelatinization. At low to moderate concentrations (≤0.5 %), FG mainly competed with starch for water, restricting the ordered arrangement and thereby reducing short-range order, and relative crystallinity. At higher concentrations (≥0.7 %), FG molecules tended to physically entangled with starch chains to form a denser network, which partially promoted molecular rearrangement during cooling. Microstructure observations confirmed denser pore walls at 0.5 % FG. These results demonstrate that FG can effectively modify the physicochemical properties of WS through water competition at low to moderate levels and physical entanglement at higher levels, providing theoretical support in starch-based foods.