Preparation of a stable gel-in-crystallized oil-in-gel type structured W₁/O/W₂ double emulsions: effect of internal aqueous phase gelation on the system stability

Abstract

This work reported a strategy to improve the storage stability of W₁/O/W₂ double emulsions with the combination of the gelled internal aqueous phase, crystallized lipid phase, and gelled external aqueous phase. The composite of κ-carrageenan and locust bean gum (κ-C/LBG) was a suitable gelling agent of the internal aqueous phase. Crystallized oils were formed by the addition of solid lipid (glycerol monostearate, GMS) into the oil phase. The double emulsions fortified by gelled inner droplets were filled in Ca-alginate hydrogel beads. The results demonstrated that GMS formed crystalline layers at the oil-water interface, and its concentration significantly affected the morphology and droplet size of double emulsions. The total polymer concentration of κ-C/LBG had an effect on the droplet size and entrapment efficiency of double emulsions. Furthermore, thermal stability study (2–21 days) and long-term storage stability study (24 weeks) showed that the gelation of the internal aqueous phase with a low concentration of 0.5 wt% κ-C/LBG appreciable increased the retention efficiency of the encapsulated double emulsions compared with the system of the non-gelled internal aqueous phase, which might provide a useful method to promote the production of double emulsions.

Graphical Abstract

Keywords:

• double emulsions
• κ-carrageenan
• locust bean gum
• internal aqueous phase gelation
• lipid crystals
• storage stability

Acknowledgments

This work was supported by the Science and Technology Achievements Transformation Project of the Government of Jiangsu Province of China (grant No. BA2014096).

Declaration of competing interest

The authors declared no conflict of interest.

Author contributions

Wenjuan Wang: Conceptualization, Investigation, Methodology, Formal analysis, Visualization, Writing - original draft. Rui Sun: Conceptualization, Formal analysis, Validation, Writing - review & editing. Zhe Dong: Data curation; Methodology. Suping Ji: Formal analysis, Writing - review & editing. Qiang Xia: Conceptualization, Project administration, Supervision, Funding acquisition, Writing - review & editing.