Formation of Pickering and mixed emulsifier systems stabilised O/W emulsions via confined impinging jets processing

This study investigates for the first time the production of 10 and 40 wt.% oil-in-water emulsions stabilised by an array of particles and mixed emulsifier (Tween20-silica) concentrations. CIJs performance was evaluated for a range of hydrodynamic conditions (energy dissipation rates, ε¯_th) and multipassing through the CIJs geometry followed by a monitoring of the emulsion storage stability. Overall, it was demonstrated that droplet size reduction was promoted as higher energy levels of ε¯_th were approached, regardless of the formulation. Following emulsion recirculation under fixed jet mass flow rate, the residence time associated with two passes was sufficient to ensure no further changes in terms of both average droplet size (d_3,2) and span of the droplet size distribution. Only when Tween20 and silica were mixed at low concentrations (0.01 and 0.10 wt.%, respectively), this emulsifier system could not promote any droplet size reduction upon both processing and multipassing. All systems showed excellent stability over 40 days of storage and it was possible to demonstrate that the combination of the emulsifiers aided in prolonging the emulsion stability. In conclusion, this investigation aims to extend the current range of emulsion microstructures that can be produced by CIJs to further enhance its industrial applicability.