Sodium caseinate as a particulate emulsifier for making indefinitely recycled pH-responsive emulsions
Yongkang Xi1, Bo Liu1, Hang Jiang2
1Research and Development Centre of Food Proteins, School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products Safety, South China University of Technology Guangzhou 510640 P. R. China feysw@scut.edu.cn.
Chemical Science
|June 14, 2021
Summary
This study introduces a highly cyclable pH-responsive emulsion using sodium caseinate (NaCas). This novel system demonstrates over 100 cycles of emulsification/demulsification, overcoming limitations in stimuli-responsive systems.
Area of Science:
- Materials Science
- Colloid and Surface Chemistry
- Biomaterials Engineering
Background:
- Stimuli-responsive emulsions offer tunable properties but often suffer from poor cyclability, limiting their practical applications.
- Protein-stabilized emulsions are a common class, but achieving robust pH-responsiveness with high cycle numbers remains a challenge.
Purpose of the Study:
- To develop a robust and highly cyclable pH-responsive emulsion system using sodium caseinate (NaCas) as the sole emulsifier.
- To investigate the potential of NaCas in enhancing the pH-responsiveness and cyclability of conventional Pickering emulsions.
- To explore the integration of catalytic functionalities into NaCas-based emulsions for advanced applications.
Main Methods:
- Preparation of pH-responsive emulsions stabilized solely by pure sodium caseinate (NaCas).
- Evaluation of emulsification/demulsification cyclability across a wide range of pH values and in challenging environments like saturated salt solutions and seawater.
- Modification of conventional nanoparticles (zein protein, SiO2) with NaCas to create pH-responsive Pickering emulsions.
- Integration of gold nanoclusters (Au NCs) with NaCas for catalytic emulsion applications.
Main Results:
- Achieved over 100 cycles of pH-triggered emulsification/demulsification with NaCas-stabilized emulsions, a significant improvement over existing systems.
- Demonstrated sustained pH-responsive properties in saturated NaCl solutions and seawater.
- Successfully engineered pH-responsive Pickering emulsions by coating nanoparticles with NaCas, exhibiting 10 cycles of switching.
- NaCas-Au NCs assembled at the oil-water interface showed excellent catalytic activity and cyclability in both aqueous and seawater media.
Conclusions:
- Pure sodium caseinate (NaCas) enables the creation of exceptionally robust and highly cyclable pH-responsive emulsions.
- NaCas can transform conventional Pickering emulsions into pH-responsive systems with enhanced performance.
- NaCas-based emulsions incorporating catalytic nanoclusters offer promising avenues for advanced applications in complex environments.
