Understanding Emulsions

An emulsion is a thermodynamically unstable mixture of two normally immiscible liquids — typically oil and water — where one phase is dispersed as fine droplets (0.1–100 µm) within the other continuous phase. The type of emulsion formed (oil-in-water or water-in-oil) depends on the volume ratio of phases, the HLB (Hydrophilic–Lipophilic Balance) value of the emulsifier, and the energy input during processing.

Role of High Shear in Emulsification

Stable emulsions require sufficient mechanical energy to break the dispersed phase into droplets small enough that Brownian motion and the stabilising surfactant layer overcome gravitational separation. A high shear homogenizer supplies this energy through intense turbulence and cavitation at the rotor–stator gap. The smaller and more uniform the droplet size, the more stable the emulsion against creaming, coalescence, and Ostwald ripening. PVA Systems process plants routinely produce emulsions with mean droplet diameters below 2 µm, lending exceptional shelf stability to pharmaceutical creams, cosmetic lotions, and food-grade sauces.