Colloidal inorganic particle-based edible oleogels and bigels

The basic building blocks which are recently being explored as structurants for oil gelation include crystalline particles (e.g. waxes), polymeric strands (e.g. cellulose derivatives) and crystalline fibers (e.g. 12 hydroxy stearic acid etc.).1-2 In the current paper, we report the use of colloidal inorganic particles, SiO2 (a food-grade additive, E 551) as new structurants to fabricate clear gels in sunflower oil.3 Oleogels with high gel strength (G\u27 \u3e 10,000 Pa), high resistance to flow (σY \u3e 100 Pa), temperature stability and a good thixotropic recovery (\u3e 70 %) were obtained at 10-15 %wt of SiO2. Cryo-SEM (along with energy-dispersive X-ray spectroscopy) revealed an interesting ‘chain-like’ arrangement of SiO2 aggregates which is responsible for creating a structural framework. The fact that the positive results were only seen with hydrophilic SiO2 (and not with functionalized hydrophobic SiO2) strongly suggests that hydrogen bonds among surface silanol groups (Si-OH) contributed to the network formation of colloidal particles. Moreover, water phase (structured using food hydrocolloids) was added to oleogel in different proportions to obtain stable ‘bigels\u27 with interesting microstructures (as seen under cryo-SEM and confocal microscope) and excellent rheological properties. Please click Additional Files below to see the full abstract