Hybrid approach to oil structuring – combining wax oleogels and capillary suspensions

Wax oleogels have been extensively studied, yet their uptake by the food industry remains slow due to their waxy mouthfeel at high gelator concentrations and weak gel strength at low concentrations. Lack of use in foods also stems from the detrimental effects of dispersed particles (protein particles, crystalline sweeteners, starch granules, etc.) on oleogelation. Rather than being seen as a hindrance, inducing interactions between particles dispersed in oil may be seen as a tool to enhance oleogel gel strength and stability. Dispersed particles can gel oil via addition of small amounts of water to form a bridged particle network that entraps liquid oil. Here, we developed a hybrid oleogel structured by both water-bridged particles and a wax crystal network and characterized its rheology and microstructure. Glass beads served as a proxy for food particles and were surface-modified to investigate the effect of wettability. Hexatriacontane was used as a model wax to limit the impact of surface-active minor components, and water was added at up to 9 vol%. Self-supporting capillary networks in canola oil formed with 30 vol% polar particles and 1 vol% water or non-polar glass beads and 3 vol% water. While 2 wt% hexatriacontane wax alone gelled the oil, the presence of glass beads without water prevented wax oleogelation. Hybrid gels formed with addition of 1 vol% or 3 vol% water for the polar and non-polar particles, respectively. The hybrid gels with polar particles weakened with increasing water content up to 9 vol% whereas the non-polar hybrids were not as sensitive to water load and their stiffness was greater than the individual contributions of the wax gel or capillary suspension alone. Overall, a wide range of textures was accessible through formation of the hybrid gels yielding a tuneable soft solid with potential for solid fat replacement.