SPG rotating membrane technique for production of food grade emulsions

A SPG rotating membrane device was used to produce food grade O/W emulsions. The emulsion droplet size: (i) decreases with increasing rotational velocity (RV), due to higher detaching drag force acting on the droplets, and (ii) increases with increasing trans-membrane pressure (TMP), due to higher interface formation rate.

The droplet size is also affected by the type and concentration of an emulsifier. Reducing the concentration of Tween 20, leads to an increase in the droplets size due to a concentration-dependent surfactant adsorption process. At Tween 20 concentrations > CMC, a rapid decrease in the interfacial tension results in production of relatively small droplets, independent of the applied RV. At concentrations ⩽ CMC, the advective mass transport accelerates adsorption, thus the droplet size reduces as the RV increases. When 1% WPI is used, it stabilises O/W emulsions produced with the membrane and showed no effect of the RV on the droplet size. The WPI-stabilised emulsions had similar droplet size to those stabilised with 1% Tween 20.

The emulsion droplet size increased as the viscosity of the continuous phase was higher. When the RV increases, the viscosity of the shear-thinning solutions reduces and the role of advective transport increases, aiding interfacial tension decrease and the production of small droplets.