Improved stability of (W₁/O/W₂) double emulsions based on dual gelation: Oleogels and hydrogels

Abstract

The objective of the present study was to improve the stability of (water‐in‐oil‐in‐water) double emulsions by dual gelation, including the gelation of lipid phase through oleogels and the gelation of continuous aqueous phase through hydrogels. Glycerol monostearate (GMS) could be used to form the oleogels and improve the stability of primary emulsions and double emulsions through reinforcing oil film. However, the redundant GMS crystals in both the oil phase and the continuous phase could cause the destabilization of double emulsions. The double emulsions reinforced by oleogels were successfully encapsulated in Ca‐alginate hydrogel beads, and this encapsulation would not influence the integrity of double emulsions. The redundant GMS crystals might cause the leakage of the inner aqueous phase in the encapsulation process, and this leakage was more likely to happen during the mixing step, rather than the crosslinking step. Ca‐alginate hydrogel beads were conducive to the confinement of the encapsulated oil globules. Practical Applications The potential applications of (water‐in‐oil‐in‐water [W1/O/W2]) double emulsions in food industry are limited by their low stability, including the weakness of the thin liquid oil film and the low thermodynamic stability of oil globules. The combination of oleogels and hydrogels could effectively improve the stability of double emulsions through the reinforcement of the oil film and the confinement of oil globules. This work provides a feasible method to improve the stability of (W1/O/W2) double emulsions, obtaining an applicable delivery system for hydrophilic active ingredients in food industry. The stable double emulsions could be used to encapsulate and control the release of hydrophilic bioactive ingredients and protect sensitive bioactive ingredients from chemical degradation. Otherwise, this system might achieve the co‐delivery of hydrophilic ingredients and hydrophobic ingredients.

Regulation Effects of Beeswax in the Intermediate Oil Phase on the Stability, Oral Sensation and Flavor Release Properties of Pickering Double Emulsions

“…Additionally, as the mass ratio of BW reached 8.0%, most of the oil droplets coalesced and formed “banded” structures, and the typical “bubble in bubble” structure of the double emulsions was lost. Probably, higher content of beeswax led to higher viscosity of primary emulsion, the inhomogeneous secondary emulsification caused the aggregation of oil droplets [ 14 , 24 ]. Besides, the large size and poor fluidity of droplets might also lead to the coalescence of adjacent droplets during microscopic observation, and thus the formation of irregular “banded” structures.…”

“…Lipid-based gelators, such as waxes, fatty acids, and monoglycerides exhibit the capacity of self-assembling in the lipid phase or at the interface to form the crystal lipid network in the lipid phase [ 13 ]. Sun, Zhang and Xia [ 14 ] used glycerol monostearate (GMS) to form the oleogels and improved the stability of double emulsions through reinforcing oil film. Gelation of the oil phase not only solidified the oil globules, but also reinforced the oil film and formed steric barrier, thereby offered flexible regulation over the stability of double emulsions.…”

Water‐in‐oleogel emulsion based on γ‐oryzanol and phytosterol mixtures: Challenges and its potential use for the delivery of bioactives

“…Water‐in‐oleogel emulsions were prepared following the method of Sun et al with modifications (Sun et al, 2019). The oil phase was prepared at 85°C with constant stirring at 350 rpm and comprised corn oil Fula® (Sovena, Algés, Portugal), polyglycerol polyricinoleate (PGPR) (Palsgaard, Juelsminde, Denmark), γ‐oryzanol (Oryza Co., Ichinomiya, Japan) and phytosterols (BASF, Lampertheim, Germany).…”

Effect of Diacylglycerol Crystallization on W/O/W Emulsion Stability, Controlled Release Properties and In Vitro Digestibility

“…One strategy to stabilize the W/O interfaces is through using fat crystals such as waxes, hydrogenated soybean oil [14], fatty alcohols and monoglycerides [15], which can create a solidified structure acting as a physical barrier that can inhibit oil and water diffusion [10,16]. The stability of encapsulated bioactives was thus enhanced because a solidified lipid phase can slow down the diffusion of the compounds liable to chemical degradation.…”

“…The stability of encapsulated bioactives was thus enhanced because a solidified lipid phase can slow down the diffusion of the compounds liable to chemical degradation. Nonetheless, the above systems still face some defects such as a high usage of solid lipid content and low storage stability of double emulsion [16]. In some cases, the existence of fat crystals in a dispersed oil phase could be a source of instability for O/W emulsions when piercing neighboring droplets, thus causing aggregation and coalescence [16].…”