Effect of Lipase on Soybean Oil‐Wheat Gluten Systems: Rheological Behavior and Molecular Mechanisms

This study investigated the regulatory effects of lipase on the viscoelastic behavior and microstructural evolution of soybean oil–wheat gluten (SOWG) composites in a model system. Dynamic frequency sweep and creep‐recovery tests showed that lipase addition significantly influenced the viscoelastic properties of SOWG after 60 min of relaxation at 37°C, with optimal effects at 800 U/g. This dosage effectively maintained elasticity and recovery ability. Molecular‐level analysis indicated enhanced hydrophobic interactions and reduced exposure of fluorescent groups, while also inhibiting covalent cross‐linking (e.g., disulfide bond formation). Size exclusion chromatography revealed a broader molecular weight distribution in lipase‐treated samples, suggesting a more complex network structure. FTIR analysis showed that 800 U/g lipase stabilized β‐sheet content, whereas excessive addition (2000 U/g) reduced structural order and storage modulus by 43% and induced irregular macroporous regions (> 5 μm). In contrast, moderate lipase levels (800 U/g) promoted a more uniform and compact gluten network, with an optimized average pore size of 2.1 ± 0.4 μm. Correlation analysis revealed a synergistic relationship between viscoelastic parameters (e.g., network area, branch length, k and J values) and microstructural evolution, indicating that lipase enables multiscale regulation to improve the structural and rheological properties of SOWG composites.