In situ real-time rheological characterization of alginate gelation

• Applicant: Professorin Dr. Natalie Germann
• Subject Area: Experimental and Theoretical Physics of Polymers ; Mechanical Properties of Metallic Materials and their Microstructural Origins ; Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: from 2018 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 389065834

• Final Report Year: 2022

Final Report Abstract

One challenging issue in rheology is to characterize materials undergoing fast transient structural changes during a physical process such as the gelation of polysaccharides. To investigate the kinetics of such a process, reliable real-time rheological monitoring is required. The scientific objective of this research project was to elucidate the gelation kinetics of alginate by means of a novel rheological approach. Various impact factors including the polysaccharide concentration, the volume and concentration of the calcium ions, the number of microholes in the geometry, as well as the applied angular frequency were studied in situ by performing an instant infusion of crosslinking agent into the samples. To achieve such an infusion, the rheometer’s base, where the alginate solutions was placed, had to be modified. In addition, a plexiglas cover was constructed for evaporation control during longterm measurements. The instant response of the polysaccharide to the presence of the calcium ions could be successfully recorded and related to a rheological equivalent to a reaction rate. The combined approach can provide new insights into the gelation kinetics of alginate. The findings of this study are also of industrial relevance as this natural polysaccharide is used in many applications in the food, cosmetic, and pharmaceutical industries.

Publications

• A Novel rheological setup for in situ mechanical characterization of alginate-Ca2+ gelation, International Congress on Rheology, Rio de Janeiro, Brazil, December 13-18, 2020
  N. Besiri, Th. B. Goudoulas, and N. Germann
  
• Custom-made setup for in situ real-time rheological characterization of fast alginate Ca 2+ gelation, Carbohydrate Polymers, 246:0144-8617, 2020
  N. Besiri, Th. B. Goudoulas, and N. Germann
  
• In situ real-time rheological characterisation of alginate-Ca2+ gelation using novel custom-made setup. Nordic Rheology Conference in Cyberspace, August 25-26, 2020
  N. Besiri, Th. B. Goudoulas, and N. Germann
  
• Novel custom-made rheometric setup for in situ real-time fast alginate-Ca2+ gelation. 12th European Congress of Chemical Engineering, Florence, Italy, December 1-4, 2020
  N. Besiri, Th. B. Goudoulas, and N. Germann
  
• In situ real-time recording of viscoelastic properties of hydrogels using novel rheological setup, Online Conference of Young Scientists, Mineral Resources-Environment-Chemical Engineering, Department of Chemical Engineering and Department of Mineral Resources, University of Western Macedonia, Kozani, Greece, February, 26-28 February, 2021
  N. Besiri, Th. B. Goudoulas, and N. Germann
  
• Rheological setup for in situ realtime crosslinking gelation, Annual European Rheology Conference in Cyberspace, April 13-14, 2021
  N. Besiri, Th. B. Goudoulas, and N. Germann
  
• Impact of CaCl2 concentration and in situ rheometric setup configuration on fast alginate-Ca2+ gelation, Annual European Rheology Conference, Sevilla, Spain, April 13-15, 2022
  I.N. Besiri, Th. B. Goudoulas, and N. Germann
  
• Impact of CaCl2 concentration and in situ rheometric setup configuration on fast alginate-Ca2+ gelation, Physics of Fluids, 34, 053104, 2022
  N. Besiri, Th. B. Goudoulas, and N. Germann
  
• In situ rheological testing of soft gel materials for pharmaceutical application, General Assembly of the European Society of Medicine (ESMED), Madrid, Spain, August 4- 6, 2022
  N. Germann