Premix emulsification: A review

Membrane emulsification is known to be a mild technique that renders narrowly dispersed emulsions at energy inputs that are orders of magnitude lower than in traditional emulsification techniques. Cross-flow membrane emulsification is most investigated and is known for the monodispersity of the emulsions produced; however, this can only be obtained at relatively low disperse phase fraction. For emulsions with higher disperse phase fractions, premix membrane emulsification is an interesting alternative that is in our opinion on the verge of breaking through. Principally, in this mild process, a coarse premix is pushed through a porous membrane leading to a fine emulsion having smaller and uniform droplets, at the expense of relatively low energy input. The mean emulsion droplet size can precisely be tuned by adjusting the pore size, transmembrane pressure and the number of cycles. The process can be used for a range of applications, including shear sensitive products such as double emulsions. The present manuscript provides an overview covering the state of the art, including insights in break-up mechanisms and the preparation of various products, and an outlook on further improvement of the process