Mechanism of the influence of single-phase dynamic gelation process on the structure and properties of bigels

The temperature-dependent properties of the single phase are crucial for the bigels structure. However, the mechanism by which the single-phase dynamic gelation process from liquid to solid influences the formation of bigels is still poorly understood. This study explored the kinetic mechanism, microstructure and mechanical properties of bigels induced by two single-phase dynamic gelation. The oleogel was prepared with beeswax and sunflower oil, while the hydrogel was made from fish scale gelatin. The results showed that low-temperature-induced single-phase gel system prompted the embedding of oleogel particles in the hydrogel network. Bigels showed uniform two-phase distribution at 25 °C and 4 °C but achieved maximal mechanical properties (hardness and elasticity) at 40 °C. All bigels exhibited good thermal reversibility and thixotropy, which demonstrated suitability as fat analogues. The bigels transitioned from a state of “flexible dominance” to “rigid dominance”, with both the recovery rate and friction coefficient declining as the single-phase temperature decreased. Raman spectroscopy revealed a significant increase in hydrogen bonds and hydrophobic interactions at lower temperatures. Molecular dynamics simulations also revealed that the rise in hydrogen bonds number (14–16 at 4 °C) and the hydrophobic shielding effect (∼50 % reduction in SASA) at lower temperatures were crucial for the dense structure of bigels. In conclusion, the mechanical properties of bigels did not positively correlate with their compactness. 40 °C was the critical temperature for the crystallization of partial beeswax, possibly realizing the optimal synergistic effect between the two phases. Thus, contrary to traditional beliefs, a moderate phase separation was more conducive to the enhancement of mechanical properties of bigels-based porcine analogues. • Formation of single-phase gel promotes the uniformity of two-phase distribution. • Moderate phase separation enhances mechanical properties of bigels. • Bigels transforms from flexible to rigid with decreasing single-phase temperature. • Hydrogen bonds and hydrophobic interaction maintains the rigidity of bigels.