Phase Transitions and Microstructure of Emulsion Systems Prepared with Acylglycerols/Zinc Stearate Emulsifier

Abstract

The emulsification processes, during which acylglycerols/zinc stearate emulsifier, water, and oil phase formed ternary systems, such as water-in-oil (W/O) emulsions, oil-in-water (O/W) dispersions, and unstable oil-water mixtures, were investigated in order to characterize the progressive transformations of the dispersed systems. The type, structure, and phase transitions of the systems were found to be determined by temperature and water phase content. Crystallization of the emulsifier caused the destabilization and subsequent phase inversion of the emulsions studied, at a temperature of 60-61 degrees C. The observed destabilization was temporary and led, at lower temperature, to W/O emulsions, "O/W + O" systems, or O/W dispersions, depending on the water content. Simultaneous emulsification and cooling of 20-50 wt % water systems resulted in the formation of stable W/O emulsions that contained a number of large water droplets with dispersed oil globules inside them ("W/O + O/W/O"). In water-rich systems (60-80 wt % of water), crystallization of the emulsifier was found to influence the formation of crystalline vesicle structures that coexisted, in the external water phase, with globules of crystallized oil phase. Results of calorimetric, rheological, and light scattering experiments, for the O/W dispersions obtained, indicate the possible transition of a monostearoylglycerol-based alpha-crystalline gel phase to a coagel state, in these multicomponent systems.

Effect of Alkyl Sulfate on the Phase Behavior of Microemulsions Stabilized with Monoacylglycerols

“…Investigations on the effectiveness of acylglycerol emulsifiers, modified with sodium and potassium soaps, showed the possibility of using such emulsifiers for the stabilization of O/W emulsions [20]. As presented elsewhere [21,22] the modification of the hydrophobic properties of acylglycerol emulsifiers may be realized by means of the controlled esterification of glycerol with fatty acids in the presence of zinc or magnesium soaps. In contrast to the use of alkali soaps, the synthesized products are very effective in the stabilization of W/O-type emulsions.…”

On the kinetics of acid sodium caseinate gelation using particle tracking to probe the microrheology

“…Confocal microscopy is used to monitor the motion of the tracer particles. Confocal microscopy provides sharper images than conventional light microscopy and can non-invasively probe opaque samples at different depths [22][23][24][25].…”

Freeze–thaw stability of water-in-oil emulsions

“…Both interfacially-active and continuous phase crystals may play a role in W/O emulsion stability [4][5][6][7][8][9]. With the former, colloids collect at the emulsion droplet interface, 'anchor' themselves onto the droplet surface, and provide a physical barrier to coalescence [10].…”