Particle stabilized water in water emulsions

Abstract

Food products often contain mixtures of incompatible water soluble macromolecules such as proteins and polysaccharides. When two aqueous solutions of incompatible macromolecules are mixed they separate into two phases each enriched in one of the two macromolecules. Contrary to oilwater (O/W) emulsions, water/water (W/W) emulsions cannot be stabilized by addition of surfactants and in food applications macroscopic phase separation is avoided by gelling one or both phases. However, recently it was shown that W/W emulsions can be stabilized to varying extents by addition of particles. Such particle stabilized emulsions are also known as Pickering emulsions and have been studied extensively for O/W emulsions. Here the literature on particle stabilization of W/W emulsions is reviewed. The behavior of particle stabilized W/W emulsions is found to be quite different from that of O/W emulsions due to the much smaller interfacial tension and the much larger length scale at which the interface expresses itself. Besides the particle size, interaction of the particles with the macromolecules in the mixture and with each other at the interface appears to play a decisive role for stabilization.

Dynamic Synthetic Cells Based on Liquid–Liquid Phase Separation

“…This has led severalg roups to describe such droplets as water-in-water (w/w) emulsions. [83] Although conceptually trivial,t he stabilisation of w/w emulsions by surface-actives peciesi st echnically challenging, due to the very low interfacial tensionsi nvolved (surfacetensions cales as thermal energy over the square of molecule size, [84] thus resulting in low values for the macromolecules involved in LLPS). Spherical colloidsw ith diameters typicallyg reater than 100 nm, including nanoparticles, [85,86] lipid vesicles [87,88] and protein clusters, [89] as well as high-aspect-ratio colloids, such as clays, [90] nanorods [91] or protein fibrils, [92] adsorb more effectively to interfaces with lows urface tension [92,93] and have therefore been used to stabiliseP EG/dextran aqueous two-phase systems (Figure 2D,E ), as well as complex coacervate droplets.…”

Stabilization of All‐in‐Water Emulsions To Form Capsules as Artificial Cells

“…The first report on the stabilization of all-in-water emulsions was reported about 10 years ago for protein particles. [16][17][18][19][20][21]45] Colloidosomes have also been produced by using latex particles, [40] and recently this was extended to polydopamine particles. [16][17][18][19][20][21]45] Colloidosomes have also been produced by using latex particles, [40] and recently this was extended to polydopamine particles.…”

“…[44] Next, Benyahia and co-workers, developed similar systemsw ith protein aggregates, polysaccharides, and nanorods. [16][17][18][19][20][21]45] Colloidosomes have also been produced by using latex particles, [40] and recently this was extended to polydopamine particles. [46] Small unilamellar vesicles were also shown to adsorb at the droplet interface.…”

“…[14] These systems are attracting growingi nterest in the field of synthetic biology and in materials chemistry. [16][17][18][19][20][21][22][23] ATPS droplets have been developed to mimic organelles or protocells;h owever,t hey lack amembrane, whichisnecessary to control entry/exit of materials from compartments. [1,2,15] In theseA TPSs, the droplets that form upon stirring the solution coalescew ith time (hours) to yield am acroscopic liquid-liquidp hase separation, but recent investigations have shown numerousw ays to stabilize the dropletinterface, preventing coalescence.…”

“…[1,2,15] In theseA TPSs, the droplets that form upon stirring the solution coalescew ith time (hours) to yield am acroscopic liquid-liquidp hase separation, but recent investigations have shown numerousw ays to stabilize the dropletinterface, preventing coalescence. [16][17][18][19][20][21][22][23] ATPS droplets have been developed to mimic organelles or protocells;h owever,t hey lack amembrane, whichisnecessary to control entry/exit of materials from compartments.…”