Designing biotechnological processes to reduce emulsions formation and improve oil recovery: Study of antifoams application

• Published in: Biochemical engineering journal 2020-11, Vol.163, p.107745, Article 107745
• Main Authors: Santos, Tatiana Porto, Cunha, Rosiane Lopes
• Format: Article
• Language: English
• Subjects: Antifoaming agents; Biotechnology; Downstream processing; Emulsion stability; Interfacial tension; Yeast cells
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2020.107745

[Display omitted] •Energy density and antifoams features are major factors affecting emulsion stability.•Yeast cells and antifoaming agents promoted formation of undesirable cream phase.•Antifoams can interfere on physical properties of yeast cells.•Emulsifier activity of antifoams depend on their physicochemical properties.•The set of methodologies can be used as a tool to choose broth composition. Fermentation aiming at oil production has emerged as an outstanding technique, but an undesirable emulsion can be formed preventing oil separation. There is still little knowledge about the mechanisms triggering the formation of such emulsions. Although this phenomenon is partly attributed to the cells presence, other essential compounds can contribute to the stability of emulsions, due to their surface properties. Thus, this study aimed at investigating the mechanisms of emulsions stabilization by Saccharomyces cerevisiae (a model microorganism) and two well-known antifoaming agents (Pluronic L81 and Antifoam C), since the surface properties of antifoams have hitherto gathered limited attention. This study also simulated conditions of energy density within the range used in similar bioprocesses. Emulsions were evaluated from droplet size, rheological properties, optical and confocal microscopy. Albeit all emulsions were stable, Pluronic L81 led to a greater reduction in interfacial tension and droplet size values, showing the drawback of its application for product recovery. It was also observed that the molecular characteristics of oils can contribute to hinder oil recovery. Therefore, the choice of an antifoam depends on the properties of the oil to be recovered. Moreover, it was demonstrated that the set of methodologies used in this study can be a tool to study the colloidal effects of fermentation components to gain insights on the development of more feasible bioprocesses.