Distributions of α- and δ-TOCopherol in Intact Olive and Soybean Oil-in-Water Emulsions at Various Acidities: A Test of the Sensitivity of the Pseudophase Kinetic Model
During the last years, the formalism of the pseudophase kinetic model (PKM) has been successfully applied to determine the distributions of antioxidants and their effective interfacial concentrations, and to assess the relative importance of emulsion and antioxidant properties (oil and surfactant na...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-12-01
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| Series: | Antioxidants |
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| Online Access: | https://www.mdpi.com/2076-3921/11/12/2477 |
| _version_ | 1797461699769401344 |
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| author | Lucía Fernández-Ventoso Artai Toba-Pérez Sonia Losada-Barreiro Fátima Paiva-Martins Carlos Bravo-Díaz |
| author_facet | Lucía Fernández-Ventoso Artai Toba-Pérez Sonia Losada-Barreiro Fátima Paiva-Martins Carlos Bravo-Díaz |
| author_sort | Lucía Fernández-Ventoso |
| collection | DOAJ |
| description | During the last years, the formalism of the pseudophase kinetic model (PKM) has been successfully applied to determine the distributions of antioxidants and their effective interfacial concentrations, and to assess the relative importance of emulsion and antioxidant properties (oil and surfactant nature, temperature, acidity, chemical structure, hydrophilic-liphophilic balance (HLB), etc.) on their efficiency in intact lipid-based emulsions. The PKM permits separating the contributions of the medium and of the concentration to the overall rate of the reaction. In this paper, we report the results of a specifically designed experiment to further test the suitability of the PKM to evaluate the distributions of antioxidants among the various regions of intact lipid-based emulsions and provide insights into their chemical reactivity in multiphasic systems. For this purpose, we employed the antioxidants α- and δ-TOCopherol (α- and δ-TOC, respectively) and determined, at different acidities well below their p<i>K</i>a, the interfacial rate constants <i>k<sub>I</sub></i> for the reaction between 16-ArN<sub>2</sub><sup>+</sup> and α- and δ-TOC, and the antioxidant distributions in intact emulsions prepared with olive and soybean oils. Results show that the effective interfacial concentration of δ-TOC is higher than that of α-TOC in 1:9 (<i>v</i>/<i>v</i>) soybean and 1:9 olive oil emulsions. The effective interfacial concentrations of tocopherols are much higher (15-96-fold) than the stoichiometric concentrations, as the effective interfacial concentrations of both δ-TOC and α-TOC in soybean oil emulsions are higher (2-fold) than those in olive oil emulsions. Overall, the results demonstrate that the PKM grants an effective separation of the medium and concentration effects, demonstrating that the PKM constitutes a powerful non-destructive tool to determine antioxidant concentrations in intact emulsions and to assess the effects of various factors affecting them. |
| first_indexed | 2024-03-09T17:23:06Z |
| format | Article |
| id | doaj.art-793c46819677468f8acdf3f93261a95a |
| institution | Directory Open Access Journal |
| issn | 2076-3921 |
| language | English |
| last_indexed | 2024-03-09T17:23:06Z |
| publishDate | 2022-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Antioxidants |
| spelling | doaj.art-793c46819677468f8acdf3f93261a95a2023-11-24T12:58:48ZengMDPI AGAntioxidants2076-39212022-12-011112247710.3390/antiox11122477Distributions of α- and δ-TOCopherol in Intact Olive and Soybean Oil-in-Water Emulsions at Various Acidities: A Test of the Sensitivity of the Pseudophase Kinetic ModelLucía Fernández-Ventoso0Artai Toba-Pérez1Sonia Losada-Barreiro2Fátima Paiva-Martins3Carlos Bravo-Díaz4Departamento Química-Física, Facultad de Química, Universidade de Vigo, 36310 Vigo, SpainDepartamento Química-Física, Facultad de Química, Universidade de Vigo, 36310 Vigo, SpainDepartamento Química-Física, Facultad de Química, Universidade de Vigo, 36310 Vigo, SpainREQUIMTE-LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, PortugalDepartamento Química-Física, Facultad de Química, Universidade de Vigo, 36310 Vigo, SpainDuring the last years, the formalism of the pseudophase kinetic model (PKM) has been successfully applied to determine the distributions of antioxidants and their effective interfacial concentrations, and to assess the relative importance of emulsion and antioxidant properties (oil and surfactant nature, temperature, acidity, chemical structure, hydrophilic-liphophilic balance (HLB), etc.) on their efficiency in intact lipid-based emulsions. The PKM permits separating the contributions of the medium and of the concentration to the overall rate of the reaction. In this paper, we report the results of a specifically designed experiment to further test the suitability of the PKM to evaluate the distributions of antioxidants among the various regions of intact lipid-based emulsions and provide insights into their chemical reactivity in multiphasic systems. For this purpose, we employed the antioxidants α- and δ-TOCopherol (α- and δ-TOC, respectively) and determined, at different acidities well below their p<i>K</i>a, the interfacial rate constants <i>k<sub>I</sub></i> for the reaction between 16-ArN<sub>2</sub><sup>+</sup> and α- and δ-TOC, and the antioxidant distributions in intact emulsions prepared with olive and soybean oils. Results show that the effective interfacial concentration of δ-TOC is higher than that of α-TOC in 1:9 (<i>v</i>/<i>v</i>) soybean and 1:9 olive oil emulsions. The effective interfacial concentrations of tocopherols are much higher (15-96-fold) than the stoichiometric concentrations, as the effective interfacial concentrations of both δ-TOC and α-TOC in soybean oil emulsions are higher (2-fold) than those in olive oil emulsions. Overall, the results demonstrate that the PKM grants an effective separation of the medium and concentration effects, demonstrating that the PKM constitutes a powerful non-destructive tool to determine antioxidant concentrations in intact emulsions and to assess the effects of various factors affecting them.https://www.mdpi.com/2076-3921/11/12/2477tocopherolantioxidantsemulsionspseudophase kinetic modeldistribution |
| spellingShingle | Lucía Fernández-Ventoso Artai Toba-Pérez Sonia Losada-Barreiro Fátima Paiva-Martins Carlos Bravo-Díaz Distributions of α- and δ-TOCopherol in Intact Olive and Soybean Oil-in-Water Emulsions at Various Acidities: A Test of the Sensitivity of the Pseudophase Kinetic Model Antioxidants tocopherol antioxidants emulsions pseudophase kinetic model distribution |
| title | Distributions of α- and δ-TOCopherol in Intact Olive and Soybean Oil-in-Water Emulsions at Various Acidities: A Test of the Sensitivity of the Pseudophase Kinetic Model |
| title_full | Distributions of α- and δ-TOCopherol in Intact Olive and Soybean Oil-in-Water Emulsions at Various Acidities: A Test of the Sensitivity of the Pseudophase Kinetic Model |
| title_fullStr | Distributions of α- and δ-TOCopherol in Intact Olive and Soybean Oil-in-Water Emulsions at Various Acidities: A Test of the Sensitivity of the Pseudophase Kinetic Model |
| title_full_unstemmed | Distributions of α- and δ-TOCopherol in Intact Olive and Soybean Oil-in-Water Emulsions at Various Acidities: A Test of the Sensitivity of the Pseudophase Kinetic Model |
| title_short | Distributions of α- and δ-TOCopherol in Intact Olive and Soybean Oil-in-Water Emulsions at Various Acidities: A Test of the Sensitivity of the Pseudophase Kinetic Model |
| title_sort | distributions of α and δ tocopherol in intact olive and soybean oil in water emulsions at various acidities a test of the sensitivity of the pseudophase kinetic model |
| topic | tocopherol antioxidants emulsions pseudophase kinetic model distribution |
| url | https://www.mdpi.com/2076-3921/11/12/2477 |
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