Synergistic enhancement of corn starch gel functionality: Soluble soybean polysaccharide and soybean oil enhance texture and improve water retention during partial gelatinization

Understanding the synergistic modification of starch gel properties is pivotal for advancing food ingredients design. This study investigates the effects of soluble soybean polysaccharide (SSPS) and soybean oil (SO) on the gelatinization, retrogradation, and gel properties of normal corn starch (NCS) under controlled partial gelatinization (61 °C, 66 °C, and 71 °C). Multi-analytical techniques (SEM, XRD, FT-IR, DSC, rheology) revealed that SSPS and SO stabilized starch's double-helical structure and elevated crystallinity by 12–22 % at 61 °C compared to untreated starch. Steady-shear rheological analysis demonstrated that SSPS and SO synergistically enhanced gel viscosity at 61 °C, with the consistency index (K) increasing from 63.36 Pa·sⁿ (untreated) to 107.33 Pa·sⁿ, and had a more significant effect than at 66 °C and 71 °C. Dynamic rheology confirmed elastic-dominant gel behavior (tan δ < 1), with SSPS-SO combinations improving storage modulus (G′) by 1.5-fold. Partial gelatinization at 61 °C significantly enhanced gel hardness (from 79 gf to 125 gf) and water-holding capacity (WHC) from 78 % to 92 % after 7-day storage, outperforming higher-temperature treatments. SSPS suppressed retrogradation, reducing gel hardness by 18–30 %, while SO reinforced the gel network through amylose-lipid complexes. These findings establish that strategic integration of SSPS and SO during mild thermal processing (61 °C) optimizes starch functionality by balancing structural integrity, viscosity, and water retention. This study establishes a mechanistic framework for optimizing starch gel functionality through mild thermal processing with natural additives, enabling tailored texture and improved water retention in starch-based foods.