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Premix membrane emulsification (ME) is a specific ME process that combines low energy requirements with high permeate fluxes. Process conditions such as membrane type (polycarbonate, Nylon, polyethersulfone and cellulose mixed esters), transmembrane pressure (1–9 bar), number of emulsification cycles (1–7) and type of emulsifier (Tween 20®, BSA) have been investigated. The results obtained indicate that, even though the type of emulsifier has a strong effect on emulsion production and final droplet size, it is possible to obtain stable emulsions by premix ME with BSA. Specifically, the use of mixed esters membranes at 9 bar and pH > 7 of the continuous phase enabled to obtain stable emulsions by premix ME with BSA.

The results obtained show that not all the polymeric membranes are suitable for premix ME. For O/W emulsions with 30% of oil fraction, Nylon, MCE and PES membranes resulted in stable emulsions for Tween 20 and 3 and 5 bar, while for emulsions with BSA only MCE membranes and 9 bar allowed to produce stable emulsions. Regarding the use of BSA as emulsifier, a minimum value of pH 7 has to be ensured to obtain stable emulsions. At this stage of the research it is not possible to conclude if membrane fouling is a main drawback for the production of stable emulsions with BSA and 30% of oil fraction in the emulsions formulation.