Modulating rheological properties and gastric emptying behavior of high internal phase emulsions via oleogelation: Influence of crystal morphology.

Modulating gastric emptying behavior of lipid-based foods is a critical strategy for regulating satiety and appetite for effective weight management. Rheological properties markedly modulate emptying rates independent of food composition. In this study, the rheological properties and gastric emptying behavior of high internal phase emulsions (HIPEs) were modulated via oleogelation, with a specific focus on the influence of crystal morphology governed by the composite gelators ratio. Results revealed that the storage modulus (G'), yield stress (τ) and viscosity of HIPEs increased with decreasing crystal size. While G' of oleogel-based HIPEs decreased with increasing temperature. It was inferred that crystal size was the key determinant of the regulation. Crystals in smaller size formed inside the emulsion droplets without affecting droplet size, thus preserving the droplet packing in the HIPEs. This packing phenomenon synergized with the crystal network to enhance the rheological strength of the matrix. In contrast, crystals in larger size induced droplet rupture and coalescence, thus attenuating the enhancement of emulsion gel strength. Dynamic in vitro digestion experiments showed that HIPEs containing crystals in smaller size could significantly delay the gastric emptying rate due to their superior shear resistance and digestive adaptability. However, the unstructured HIPEs rapidly destabilized during gastric digestion, leading to the rapid emptying of lipids. This study reveals the dual regulatory roles of crystal morphology in the rheological properties and functional characteristics of HIPEs, thereby expanding the application of oleogelation technology and supporting the development of novel lipid control strategies.