Impact of the Mechanical Stress and Stress Residence Time on Proteins in Emulsion Formulation Within the Premix Membrane Emulsification

In biotechnological processes, one major challenge in the production and formulation process chain is the downstream processing. In the case of protein and enzyme processing, downstream processing can cause protein denaturation or structural alterations leading to an undesired decrease in the product quality or even a product loss. Premix membrane emulsification (PME) is a gentle method to produce emulsions during downstream processing. In PME, a coarsely dispersed premix is forced through a membrane using a pressure gradient which creates a fine emulsion or dispersion due to droplet disruption in the membrane pores. Its industrial application is still limited due to the lack of knowledge, especially on the control and minimization of the complex mechanical stress on proteins and enzymes. In the present study, the stress residence time behavior in PME in the membrane pores is characterized in three stages: (1) stress in the pore on the droplet leading to droplet deformation and breakup, (2) stress on the protein at the solid-liquid interface and (3) stress on the protein at the liquid-liquid interface.