Fumed silica-based organogels and 'aqueous-organic' bigels

We report the use of fumed silica (hydrophilic colloidal silica particles) to generate triglyceride solvent-based soft matter systems (organogels and bigels). Interestingly, the bigels showed a better gel strength compared to organogels while showing a comparatively weaker thixotropic recovery. Electron microscopy and energy dispersive X-ray spectroscopy were used to understand the microstructure of these new thixotropic molecular gel systems with respect to the fractal-like aggregation of silica particles as well as the percolating network of organic-aqueous phases

Rheological characterization of gel-in-oil-in-gel type structured emulsions

AbstractWe report the fabrication of multiple emulsions where both the enclosed and the external water phases are structured using a combination of two non-gelling biopolymers. Emulsions (with gelled inner water droplets and gelled water continuous phase) were created using a simple ‘one-step’ process where the oil phase (triglyceride oil and polyglycerol polyricinoleate) and the water phase (containing a combination of locust bean gum and carrageenan) were emulsified at an elevated temperature (70 °C) followed by cooling to room temperature. The temperature triggered gelling of the synergistic biopolymer combination led to the formation of structured emulsions on cooling. Flowable to self-standing emulsion gels could be prepared by changing the total concentration of polymers (and the ratios of the individual polymers) as confirmed from low amplitude oscillatory shear rheology and creep recovery measurements. The cryo-scanning electron microscopy images of freeze-fractured emulsion samples revealed the presence of gelled inner water droplets. Further, when subjected to heating and cooling cycles, emulsions displayed reversible rheological changes which could be tuned by simply changing the total polymer concentration and the proportions of individual polymers. Such biopolymer-based structured emulsions with interesting microstructure and rheological properties could find potential applications in bio-related fields like food structuring

Biopolymer-based structuring of liquid oil into soft solids and oleogels using water-continuous emulsions as templates

Physical trapping of a hydrophobic liquid oil in a matrix of water-soluble biopolymers was achieved using a facile two-step process by first formulating a surfactant-free oil-in-water emulsion stabilized by biopolymers (a protein and a polysaccharide) followed by complete removal of the water phase (by either high- or low-temperature drying of the emulsion) resulting in structured solid systems containing a high concentration of liquid oil (above 97 wt %). The microstructure of these systems was revealed by confocal and cryo-scanning electron microscopy, and the effect of biopolymer concentrations on the consistency of emulsions as well as the dried product was evaluated using a combination of small-amplitude oscillatory shear rheometry and large deformation fracture studies. The oleogel prepared by shearing the dried product showed a high gel strength as well as a certain degree of thixotropic recovery even at high temperatures. Moreover, the reversibility of the process was demonstrated by shearing the dried product in the presence of water to obtain reconstituted emulsions with rheological properties comparable to those of the fresh emulsion

A foam-templated approach for fabricating organogels using a water-soluble polymer

We report a unique approach of using a water soluble polymer (a cellulose derivative) to generate organogels via a facile, low temperature process. This finding is an important step towards the development of liquid oil-based soft matter systems for applications in non-bio and bio-related fields

High internal phase emulsion gels (HIPE-gels) prepared using food-grade components

We report a new approach of using dispersed water phase gelation as a mode to create oil continuous emulsion gels. The low temperature gelation property of synergistic hydrocolloid combinations was exploited to develop elastic soft solids using only food-grade components

Edible oleogels based on water soluble food polymers: preparation, characterization and potential application

Oil structuring using food-approved polymers is an emerging strategy and holds significant promise in the area of food and nutrition. In the current study, edible oleogels (containing >97 wt% of sunflower oil) were prepared using a combination of water soluble food polymers (methylcellulose and xanthan gum) and further evaluated for potential application as a shortening alternative. Microstructure studies (including cryo-SEM) and rheology measurements were conducted to gain more insights into the properties of these new types of oleogels. In addition, the functionality of oleogel as a shortening alternative was studied in terms of batter properties and the texture analysis of cakes and compared to the reference batches made using either oil, commercial shortening or cake margarine. Interestingly, while the batter properties (air incorporation, rheology and microstructure) of the oleogel batch were more close to the oil batch, the textural properties of cakes were significantly better than oil and resembled more to the cakes prepared using shortening and margarine