Large and small amplitude oscillatory shear techniques evaluate the nonlinear rheological properties of Ficus pumila polysaccharide -wheat starch gel.

Polysaccharides are used in starch-based product formulations to enhance the final quality of food products. This study examined the interaction mechanisms in Ficus pumila polysaccharide (FPP) and wheat starch (WS) gel systems with varying FPP concentrations using linear and nonlinear rheological analysis. Physicochemical structural analyses showed non-covalent FPP-WS interactions, strengthening hydrogen bonding between molecules and promoting water binding and ordered structure generation during WS gel aging. Small amplitude oscillatory shear analyses revealed that elevated FPP concentrations led to increased storage modulus (G'), loss modulus (G"), critical strains (From 29.02 % to 53.32 %) and yield stresses (From 0.94 Pa to 30.97 Pa) in the WS gel system, along with improved resistance to deformation and short-term regeneration. In the nonlinear viscoelastic region, FPP-WS gels shifted from elastic to viscous behavior. Higher FPP concentrations displayed increased energy dissipation, strain hardening (S>0, e/e > 0) and shear thinning (T<0, v/v<0). FPP contributes more nonlinearity in the dynamic flow field as showed by the high harmonic ratio, with a larger I/I values overall. This study highlights FPP's potential in starch gel food processing, and offers a theoretical basis for understanding hydrocolloid-starch interactions.