Transforming monomeric globulins into pickering particles to stabilize nanoemulsions: Contribution of trehalose

Abstract

Monomeric globulins have been widely employed in food-grade nanoemulsion preparation owing to their outstanding emulsification performance. However, a limitation to stabilize nanoemulsions during storage exists when using monomeric globulin as sole emulsifier, mainly due to the low structural stability of protein during emulsification and at water-oil interface. In the current work, an efficient strategy to fabricate ultra-stable protein-based nanoemulsions was proposed through the incorporation of trehalose to enhance the structural stability of bovine serum albumin (as a model monomeric globulin) in the aqueous phase. The as-prepared nanoemulsions exhibited a high stability against droplet flocculation and coalescence during emulsification and upon long-term storage. Further analyses indicated that the presence of trehalose could form a “shell” structure around protein particles to protect protein against denaturation, unfolding and aggregation during microfluidization. The globulins in trehalose-rich system could behave as a kind of soft nanoparticles with a strong structural integrity and were unaffected by adsorption at the interface. Moreover, the existence of abundant aggregated trehalose greatly favored protein diffusion and adsorption and contributed to more balanced protein wettability, thus allowing monomeric globulins to stabilize more interfaces with Pickering effect. The findings are of value for providing a strategy to prepare stable nanoemulsion using monomeric globulins as the sole emulsifier by simply transforming monomeric globulins into Pickering nanoparticles with the addition of trehalose.