Formation and stability of oil-in-water emulsions based on components of bioprocesses: A microfluidic analysis

Abstract

Undesirable oil-in-water (O/W) emulsions are typically developed and stabilized during biotechnological processes, hampering the recovery of oil-based bioproducts. Such emulsions emerge in the fermentation medium due not only to the process conditions, but mainly to the broth composition. In this light, an in-depth study of the formation and stability of these colloidal systems is paramount to establish an appropriate formulation, especially considering some highly relevant components for bioprocesses (such as antifoams). In general, antifoams are added to the fermentation broth with little control, although they can potentially lead to the formation of undesirable emulsions. In this context, we analyzed O/W emulsions stabilized by yeast cells and two widely used antifoaming agents (Pluronic L81 and Antifoam C) within microfluidic glass capillaries to perform a high-throughput analysis and reveal the role of these components in the formation of stable emulsions. In general, both antifoams and yeast cells enabled the formation of droplets depending on the characteristics of the oily phase, but marked differences were observed in the stability of the formed emulsions. For instance, Pluronic L81 allowed the formation of a highly stable emulsion, while Antifoam C produced droplets more susceptible to destabilization. Such results indicate that a particular choice of the pair antifoam-oily phase can facilitate the destabilization process and even impair the mechanism of droplet formation.