Recent advances on food-grade water-in-oil emulsions: Instability mechanism, fabrication, characterization, application, and research trends

Abstract

Owing to their promising application prospects, water-in-oil (W/O) emulsions have aroused continuous attention in recent years. However, long-term stability of W/O emulsions remains a particularly challenging problem in colloid science. With the increasing demand of consumers for natural, green, and healthy foods, the heavy reliance on chemically synthesized surfactants to achieve long-term stability has become the key technical defect restricting the application of W/O emulsions in food. To design and manufacture W/O emulsions with long-term stability and clean label, a comprehensive understanding of the fundamentals of the W/O emulsion system is required. This review aims to demystify the field of W/O emulsions and update its current research progress. We first provide a summary on the essential basic knowledge regarding the instability mechanisms, including physical and chemical instability in W/O emulsions. Then, the formulation of the W/O emulsion system is introduced, particularly focusing on the use of natural stabilizers. Besides, the characterization and application of W/O emulsions are also discussed. Finally, we propose promising research trends, including (1) developing W/O high internal phase emulsions (HIPEs) as fat mimetic and substitute, (2) promising formulation routine for long-term stable double emulsions, and (3) searching for novel plant-derived stabilizers of W/O emulsions.

Keywords:

• W/O emulsions
• instability mechanisms
• preparation
• Pickering stabilization
• applications

Authors’ contribution

Xin Hong drafted the manuscript. Qiaoli Zhao helped with language editing. Yuanfa Liu and Jinwei Li critically revised the manuscript.

Disclosure statement

The authors declare no conflicts of interest.

Additional information

Funding

This work was supported by National Natural Science Foundation of China (32072138).