Preparation and characterization of high speed jet modified tapioca starch-guar gum complexes: rheological, structural, and molecular dynamics simulation studies

Starch and hydrocolloids are key functional ingredients for improving product quality and cost-effectiveness. However, interactions between physically modified tapioca starch (TS) and guar gum (GG) remain poorly characterized. This study modified TS through high speed jet (HSJ) at 60–220 MPa, and systematically investigated its interaction with GG at mass ratios from 0.10:0 to 0.06:0.04 ( w /w) using rheology, XRD, FTIR, SEM, and molecular dynamics (MD) simulation. Among the tested mass ratios and pressures, the optimal conditions (HSJ-TS:GG = 0.06:0.04 w /w, 220 MPa) maximized viscosity, shear stress, and stable weak gel behavior. FTIR revealed enhanced hydroxyl interactions and a critical structural transition above 140 MPa. XRD and SEM analyses revealed increased crystallinity (from 11.7% to 30.3%) and a compact porous microstructure. MD simulations identified van der Waals forces and hydrogen bonds as the main binding mechanisms; compared with a multi-branched starch model, a low-branched starch model showed stronger affinity to GG (ΔG bind = −111.31 vs. -89.77 kJ/mol). These findings clarify modified starch-colloid interactions, support food formulation optimization and expand TS/GG applications in rheologically stable, cost-effective foods.