Continuous production of dense emulsions via vortex-based hydrodynamic cavitation: Influence of operating temperature and oil-aqueous phase characteristics

Emulsions find diverse applications across a wide range of industries. In the present work, dense emulsions (oil volume fraction, α_O > 0.05 ) were produced in a continuous mode using a vortex-based hydrodynamic cavitation device (VD). Influence of operating temperature and oil-aqueous phase composition on the resulting droplet size distribution (DSD) was investigated. Two oils, namely rapeseed oil (RO) and anhydrous milk fat (AMF) were used. Two different aqueous phases namely deionised water and deionised water with milk (base of the ice cream mix) were used. The influence of operating temperature on DSD of continuously produced emulsions was investigated for different oil volume fractions, pressure drops, and the flow rate ratios (Q/q, where Q is flow through VD and q is net flow of emulsion). The increase in temperature from 22°C to 45°C led to ∼27% reduction in the Sauter mean diameter (d₃₂). The DSD of oils in ice-cream mix was found to be uni-modal unlike in water which exhibited bi-modal DSD. This work highlights the effect of temperature and oil-aqueous phase composition on DSDs. The presented results will be useful for selecting appropriate temperature and operating parameters while designing VD-based emulsification processes.