Recent progress in oil-in-water-in-oil (O/W/O) double emulsions

Abstract

Oil-in-water-in-oil (O/W/O) double emulsions are recognized as an advanced design route for oil structuring that shows promising applications in the pharmaceutical, cosmetic, and food fields. This review summarizes the main research advances of O/W/O double emulsions over the past two decades. It mainly focuses on understanding the preparation strategies, stabilization mechanism, and potential applications of O/W/O double emulsions. Several emulsification strategies are discussed, including traditional two-step emulsification method, phase-inversion approach, membrane emulsification, and microfluidic emulsification. Further, the role of interfacial stabilizers and viscosity in the stability of O/W/O double emulsions will be discussed with a focus on synthetic emulsifiers, natural biopolymer sand solid particles for achieving this purpose. Additionally, analytical methods for evaluating the stability of O/W/O double emulsions, such as advanced microscopy, rheology, and labeling assay are reviewed taking into account potential limitations of these characterization techniques. Moreover, possible innovative food applications are highlighted, such as simulating fat substitutes to decrease the trans- or saturated fatty acid content and developing novel delivery and encapsulation systems. This review paves a solid way for the exploration of O/W/O double emulsions toward large-scale implementation within the food industry.

Keywords:

• Emulsification
• innovative food
• O/W/O double emulsions
• stabilization mechanism

Conflicts of interest

The authors declare no conflict of interest.

CrediT author statement

Zijian Zhi: Investigation, Methodology, Writing-Original draft.

Rui Liu: Conceptualization, Visualization.

Wenjun Wang: Writing-Reviewing & Editing.

Koen Dewettinck: Resources, Funding acquisition.

Filip Van Bockstaele: Validation, Project administration.

Additional information

Funding

The research was supported by the project of National Natural Science Foundation of China (No. 32111530082) and Key Research and Development Program of Shandong Province (2021CXGC010807). Vandemoortele Lipids is acknowledged for financially supporting the Vandemoortele Centre “Lipid Science and Technology” at Ghent University. In addition, we gratefully acknowledge helpful assistance in proofreading the article by Dr. C.D. Wang.