However, it is possible to increase the stability of structured organogel-emulsions by slowing the transition from the α-gel to the coagel phase. The polymorphic transition of the MG limits the useful life of emulsions due to the loss of nanostructured water. The destabilization of structured emulsions is mainly caused by a polymorphic transformation of MG.
However, some emulsions structured only with MG are prone to phase separation and syneresis of water after four weeks of storage at room temperature (about 20 ☌). In o/w emulsions structured with MG, structural and rheological properties have been studied finding that in the lamellar phase, after the homogenization, the MG and the co-emulsifiers assemble themselves in hydrated lamellar structures and form a gel network like fat and organogels, in which the oil droplets are surrounded by alternating MG bilayers and water. It has been reported that it is possible to obtain structured emulsions, resembling trans-free vegetable fats, which can be used in different food products. These molecules self-assemble both in the presence of water and oil in various types of mesophases depending on the type of continuous phase and their concentration. The MG are low molecular weight lipids, which have a single fatty acid chain attached to a glycerol main chain, providing amphiphilic characteristics and being important emulsifiers. Įmulsions based on structuring with monoglycerides (MG) are widely used in food products and cosmetics. It has also been shown that smaller droplet sizes increase the bioavailability of certain types of lipophilic substances loaded in emulsions. It is also important to consider the concentration of surfactant since a suitable thickness of the interface surrounding the drops provides a greater viscosity to the dispersed phase that in conjunction with a structured continuous phase can provide gel or paste characteristics for different applications, where semisolid behavior is required. By reducing the droplet size in emulsions, the interaction area between droplets is increased, presenting greater stability to the aggregation of particles, and reducing the phenomena of coalescence and flocculation. However, it is well known that the drop size reduction is limited by the viscosity of the oil phase. Therefore, it is possible to obtain emulsions by mechanisms such as mixing and homogenization. The development of w/o emulsions is based on dispersion and force methods, the so-called high-energy physical mechanisms, which by disruptive forces mechanically disintegrate the aqueous phase into small droplets that disperse in the continuous oil phase. The low energy emulsions drop out the phase in minor proportion to become under certain specific conditions of concentration, temperature, and agitation metastable systems. Emulsions can be obtained by different methods, which can be classified as high and low energy. The w/o emulsions have water droplets surrounded by an interfacial film where some surfactants can be found, these drops are dispersed in the continuous oil phase. Organogel-emulsions (w/o) has a continuous oil phase structured from a self-assembling gelling agent giving semi-solid characteristics like those of an organogel. Also, pharmaceutical and food industries have used emulsions to load some bioactive compounds and include them in a final product. Some of these products or compound matrices require emulsions to have specific characteristics. In the last decade, interest in the introduction of micronutrients and nutraceuticals as part of a food matrix or products with a contribution to health has grown exponentially. The properties of the organogelated emulsions are explained by the interface-interface interactions present between the particles and the reduced mobility, which slows the phase separation. No variability was found in modules G′ and G″, so these systems have good mechanical stability. Also, a change in the crystallization profile of the aqueous and oily phases concerning to time was also found, the crystallization signals coinciding (≈ − 40 ☌), indicating a better organization by the phases. The presence of crystalline structures was observed in the continuous phase characteristic of some organogels and a smaller distribution of sizes as a function of time. Micrographs, differential scanning calorimetry, and rheology tests were performed. Monoglycerides were used as the gelling agent and polyglycerol polyricinoleate as the surfactant.
Two oil phases (canola and coconut oil) were used to assess the impact of the different vegetable oils. The objective of the present investigation was to evaluate the physical stability of emulsions (w/o) with a gel as an oil phase.