Effects of Cactus Polysaccharide on Pasting, Rheology, Structural Properties, In Vitro Digestibility, and Freeze–Thaw Stability of Rice Starch

This study combined rice starch (RS) with cactus polysaccharide (CP) at different composites (0.6%, 1.2%, 1.8%, 2.4%, and 3.0%, w/w), and analyzed the variations in the complex gelatinization properties, rheological properties, thermal properties, structural properties, digestibility, and freeze–thaw stability. As a result, the pasting parameters (p < 0.05) and storage modulus (G′) together with the loss modulus (G″) decreased as the CP concentration increased; meanwhile, the RS and the CP–RS gels were pseudoplastic fluids. As revealed by differential scanning calorimetry (DSC), incorporating CP into the starch elevated the starch gelatinization temperature while decreasing gelatinization enthalpy, revealing that CP effectively retarded long-term retrogradation in RS. The gel microstructure and crystallization type altered after adding CP. Typically, CP inclusion could enhance the proportion of resistant starch and slowly digestible starch (SDS), thereby slowing RS hydrolysis. Concurrently, adding CP promoted the RS freeze–thaw stability. These findings could potentially aid in the innovation of CP-based food products.