Alginate-Chitosan Microgel Particles, Water–Oil Interfacial Layers, and Emulsion Stabilization
In this work, alginate-chitosan microgel particles were formed at different pH levels with the aim of using them as viscoelastic interfacial layers, which confer emulsion stability to food systems. The particles’ size and structural characteristics were determined using laser diffraction, confocal l...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-06-01
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| Series: | Colloids and Interfaces |
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| Online Access: | https://www.mdpi.com/2504-5377/7/2/48 |
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| author | Aggelos Charisis Eleni P. Kalogianni |
| author_facet | Aggelos Charisis Eleni P. Kalogianni |
| author_sort | Aggelos Charisis |
| collection | DOAJ |
| description | In this work, alginate-chitosan microgel particles were formed at different pH levels with the aim of using them as viscoelastic interfacial layers, which confer emulsion stability to food systems. The particles’ size and structural characteristics were determined using laser diffraction, confocal laser microscopy (CLSM), and time-domain nuclear magnetic resonance (TD-NMR). The pH affected the microgel characteristics, with larger particles formed at lower pH levels. <i>T</i><sub>2</sub> relaxation measurements with TD-NMR did not reveal differences in the mobility within the particles for the different pH levels, which could have been related to the more or less swollen structure. The rate of adsorption of the particles at the sunflower oil–water interface differed between particles formed at different pH levels, but the equilibrium interfacial tension of all systems was similar. Higher interfacial dilatational viscoelasticity was obtained for the systems at lower pH (3, 4, 5), with <i>G</i>’ reaching 13.6 mN/m (0.1 Hz) at pH 3. The interfacial rheological regime transitioned from a linear elastic regime at lower pH to a linear but more viscoelastic one at higher pH. The thicker, highly elastic interfacial layer at low pH, in combination with the higher charges expected at lower pH, was related to its performance during emulsification and the performance of the emulsion during storage. As revealed by laser diffraction and CLSM, the droplet sizes of emulsions formed at pH 6 and 7 were significantly larger and increased in size during 1 week of storage. CLSM examination of the emulsions revealed bridging flocculation with the higher pH. Nevertheless, all emulsions formed with microgel systems presented macroscopic volumetric stability for periods exceeding 1 week at 25 °C. A potential application of the present systems could be in the formation of stable, low-fat dressings without the addition of any emulsifier, allowing, at the same time, the release of the bioactive compounds for which such particles are known. |
| first_indexed | 2024-03-11T02:36:23Z |
| format | Article |
| id | doaj.art-0153036b3cac42c68c2600ff4c7302fc |
| institution | Directory Open Access Journal |
| issn | 2504-5377 |
| language | English |
| last_indexed | 2024-03-11T02:36:23Z |
| publishDate | 2023-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Colloids and Interfaces |
| spelling | doaj.art-0153036b3cac42c68c2600ff4c7302fc2023-11-18T09:53:38ZengMDPI AGColloids and Interfaces2504-53772023-06-01724810.3390/colloids7020048Alginate-Chitosan Microgel Particles, Water–Oil Interfacial Layers, and Emulsion StabilizationAggelos Charisis0Eleni P. Kalogianni1Department of Food Science and Technology, International Hellenic University, Alexander Campus, 57400 Thessaloniki, GreeceDepartment of Food Science and Technology, International Hellenic University, Alexander Campus, 57400 Thessaloniki, GreeceIn this work, alginate-chitosan microgel particles were formed at different pH levels with the aim of using them as viscoelastic interfacial layers, which confer emulsion stability to food systems. The particles’ size and structural characteristics were determined using laser diffraction, confocal laser microscopy (CLSM), and time-domain nuclear magnetic resonance (TD-NMR). The pH affected the microgel characteristics, with larger particles formed at lower pH levels. <i>T</i><sub>2</sub> relaxation measurements with TD-NMR did not reveal differences in the mobility within the particles for the different pH levels, which could have been related to the more or less swollen structure. The rate of adsorption of the particles at the sunflower oil–water interface differed between particles formed at different pH levels, but the equilibrium interfacial tension of all systems was similar. Higher interfacial dilatational viscoelasticity was obtained for the systems at lower pH (3, 4, 5), with <i>G</i>’ reaching 13.6 mN/m (0.1 Hz) at pH 3. The interfacial rheological regime transitioned from a linear elastic regime at lower pH to a linear but more viscoelastic one at higher pH. The thicker, highly elastic interfacial layer at low pH, in combination with the higher charges expected at lower pH, was related to its performance during emulsification and the performance of the emulsion during storage. As revealed by laser diffraction and CLSM, the droplet sizes of emulsions formed at pH 6 and 7 were significantly larger and increased in size during 1 week of storage. CLSM examination of the emulsions revealed bridging flocculation with the higher pH. Nevertheless, all emulsions formed with microgel systems presented macroscopic volumetric stability for periods exceeding 1 week at 25 °C. A potential application of the present systems could be in the formation of stable, low-fat dressings without the addition of any emulsifier, allowing, at the same time, the release of the bioactive compounds for which such particles are known.https://www.mdpi.com/2504-5377/7/2/48biopolymer microgelsinterfacial tensioninterfacial rheologyparticle-stabilized emulsions |
| spellingShingle | Aggelos Charisis Eleni P. Kalogianni Alginate-Chitosan Microgel Particles, Water–Oil Interfacial Layers, and Emulsion Stabilization Colloids and Interfaces biopolymer microgels interfacial tension interfacial rheology particle-stabilized emulsions |
| title | Alginate-Chitosan Microgel Particles, Water–Oil Interfacial Layers, and Emulsion Stabilization |
| title_full | Alginate-Chitosan Microgel Particles, Water–Oil Interfacial Layers, and Emulsion Stabilization |
| title_fullStr | Alginate-Chitosan Microgel Particles, Water–Oil Interfacial Layers, and Emulsion Stabilization |
| title_full_unstemmed | Alginate-Chitosan Microgel Particles, Water–Oil Interfacial Layers, and Emulsion Stabilization |
| title_short | Alginate-Chitosan Microgel Particles, Water–Oil Interfacial Layers, and Emulsion Stabilization |
| title_sort | alginate chitosan microgel particles water oil interfacial layers and emulsion stabilization |
| topic | biopolymer microgels interfacial tension interfacial rheology particle-stabilized emulsions |
| url | https://www.mdpi.com/2504-5377/7/2/48 |
| work_keys_str_mv | AT aggeloscharisis alginatechitosanmicrogelparticleswateroilinterfaciallayersandemulsionstabilization AT elenipkalogianni alginatechitosanmicrogelparticleswateroilinterfaciallayersandemulsionstabilization |