What is water-in-oil microemulsion?

Water–in–oil (w/o) microemulsions consist of spherically dispersed water droplets confined inside a continuous oil phase by an interfacial sheath of a surfactant-cosurfactant mixture.

Does Zein dispersion in water produce w/o emulsions?

It was found that zein colloidal particle dispersions in water (i.e., not dispersed in the oil phase) at pH 4.0, blended with soybean oil, produced W/O emulsions with a water content up to 30 vol%, although the water droplets were large (~100 μm) and only stable for ~ 1 h (Rutkevičius et al., 2018).

Can water-in-oil emulsions be biodegradable?

Designing water-in-oil (W/O) emulsions is a promising strategy to incorporate water. W/O emulsions stabilized by surfactants, biopolymers and/or particles are reviewed. There is a growing need for emulsifiers that are ‘clean-label’ and biodegradable. Use of bio-derived Pickering particles is a relatively recent endeavour.

Are wpm emulsions stable in the oil phase?

Very recent work (Zembyla, Lazidis, Murray, & Sarkar, 2020), however, has shown that subsequent shearing and/or heating of these same WPM + polyphenol-stabilized W/O emulsions disrupts these aggregates in the oil phase but the W/O emulsions remain stable.

Why are biopolymers used in w/o emulsions?

Biopolymers have been mainly used in W/O emulsions as viscosity-modifiers of the aqueous phase, which tends to improve the kinetic stability of the droplets whilst the primary emulsifying agent is some other species, usually a low molecular weight surfactant.

How do biopolymers affect emulsion stability?

Gelling or increasing the viscosity of the aqueous phase of the droplets, for example by adding biopolymers alongside suitable processing conditions (temperature, pH, etc.), can also lead to modifications that affect emulsion stability, but the emulsion rheology itself to a lesser extent.