Gelation mechanism dependent linear/nonlinear rheological behavior, structural characteristics, and...

This study constructed bigels based on two distinct oleogel gelation mechanisms, namely crystalline particle-type β-sitosterol + monoglyceride (βM) and self-assembled fiber-type β-sitosterol + γ-oryzanol (βγ), to elucidate their effects on bigel microstructure, rheological behavior, and deformation-related structural properties. Confocal microscopy qualitatively suggested that βM-bigels exhibited a more integrated biphasic morphology, whereas βγ-bigels showed clearer oil-water interfaces and less apparent phase interpenetration. With increasing oleogel content, both systems developed stronger network structures. Notably, βM-bigels exhibited greater linear viscoelasticity and deformation resistance, with terminal G' in the linear viscoelastic region increasing from 145.42 to 33,308.32 Pa and yield stress rising from 11.06 to 54.59 Pa, compared with 84.02-26,284.11 Pa and 8.18-47.50 Pa for βγ-bigels, respectively. Large-amplitude oscillatory shear further revealed larger elastic Lissajous-Bowditch loops and wider secondary viscous loops for βM-bigels, indicating more pronounced strain stiffening and shear thinning. In addition, βM-bigels showed the lower adhesiveness and clearest fork marks, indicating more favorable IDDSI-related textural criteria. In a separate butter-substitution application, βM-butters exhibited microstructure and rheological behavior closer to those of pure butter, and showed a more similar odor-response pattern in electronic nose analysis, whereas βγ-butters showed superior antioxidant activity and health-related benefits. Overall, gelation mechanism plays a key role in determining the nonlinear rheological and performance of bigels, highlighting their versatility in different food application scenarios.