Cellulose-stabilized oil-in-water emulsions: Structural features, microrheology, and stability

Carolina Costa; Pedro Rosa; Alexandra Filipe; Bruno Medronho; Anabela Romano; Lucy Liberman; Yeshayahu Talmon; Magnus Norgren

doi:10.1016/j.carbpol.2020.117092

Cellulose-stabilized oil-in-water emulsions: Structural features, microrheology, and stability

Carbohydr Polym. 2021 Jan 15:252:117092. doi: 10.1016/j.carbpol.2020.117092. Epub 2020 Sep 15.

Authors

Carolina Costa¹, Pedro Rosa², Alexandra Filipe³, Bruno Medronho⁴, Anabela Romano⁵, Lucy Liberman⁶, Yeshayahu Talmon⁷, Magnus Norgren⁸

Affiliations

¹ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden. Electronic address: carolina.costa@miun.se.
² MED - Mediterranean Institute for Agriculture, Environment and Development, University of Algarve, Faculty of Sciences and Technology, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal. Electronic address: a57578@ualg.pt.
³ CIEPQPF, Department of Chemical Engineering, University of Coimbra, Pólo II - R. Silvio Lima, 3030-790 Coimbra, Portugal. Electronic address: alexandraf@eq.uc.pt.
⁴ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden; MED - Mediterranean Institute for Agriculture, Environment and Development, University of Algarve, Faculty of Sciences and Technology, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal. Electronic address: bfmedronho@ualg.pt.
⁵ MED - Mediterranean Institute for Agriculture, Environment and Development, University of Algarve, Faculty of Sciences and Technology, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal. Electronic address: aromano@ualg.pt.
⁶ Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute (RBNI), Technion-Israel Institute of Technology, Haifa 3200003, Israel. Electronic address: lucylib@technion.ac.il.
⁷ Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute (RBNI), Technion-Israel Institute of Technology, Haifa 3200003, Israel. Electronic address: ishi@technion.ac.il.
⁸ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden. Electronic address: magnus.norgren@miun.se.

PMID: 33183583
DOI: 10.1016/j.carbpol.2020.117092

Abstract

Cellulose-based oil-in-water (O/W) emulsions were studied by diffusing wave spectroscopy (DWS) regarding the effect of the cellulose concentration and mixing rate on the average droplet size, microrheological features and stability. Furthermore, the microstructure of these emulsions was imaged by cryo-scanning electron microscopy (cryo-SEM). The micrographs showed that cellulose was effectively adsorbed at the oil-water interface, resembling a film-like shell that protected the oil droplets from coalescing. The non-adsorbed cellulose that was observed in the continuous aqueous medium, contributed to the enhancement of the viscosity of the medium, leading to an improvement in the stability of the overall system. Generally, the higher the cellulose concentration and mixing rate, the smaller the emulsion droplets formed, and the higher was their stability. The combination of both techniques, DWS and cryo-SEM, revealed a very appealing and robust methodology for the characterization and design of novel emulsion-based formulations.

Keywords: Cellulose; Cryo-scanning electron microscopy; Diffusing wave spectroscopy; Emulsions; Microrheology.