Modulation of Physical Stability in Pickering Double Emulsions: Role of Interface-Oil Phase Distribution of Crystallizable Emulsifiers

Pickering double emulsions, characterized by their multi-chamber and multi-interface structure, historically faced challenges in physical stability due to solute exchange and film fusion, constraining their use in food, cosmetic, and pharmaceutical sectors. This study introduces an innovative approach to structuring the intermediate oil phase of these emulsions by employing crystallizable monoglycerides. We strategically manipulated the distribution of monoglycerides across the internal and external interfaces, as well as within the oil phase, to enhance emulsion stability. Our findings revealed that the distribution pattern of monoglycerides significantly influenced the emulsion’s resistance to solute exchange and film fusion. Notably, the internal interface crystal barrier effectively inhibited solute exchange, while the distribution pattern at the external interface showed the greatest reduction in membrane fusion. Additionally, crystallization within the oil phase is found to be sensitive to creaming, which is exacerbated under conditions of osmotic pressure or freeze-thaw cycles. Comprehensive rheometer and tribological testing indicated that monoglycerides distributed at the interface, which withstand processing conditions, imparted the double emulsions with enhanced elastic rheological properties and improved stiffness. This research contributes novel insights into the structure-function relationship of multiple emulsions. It opens up new avenues for engineering the interfacial structure and optimizing the physical stability and rheological properties of emulsion systems, making it a significant advancement in the field.