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Martínez-Senra T, Losada-Barreiro S, Bravo-Díaz C. Efficiency of δ-Tocopherol in Inhibiting Lipid Oxidation in Emulsions: Effects of Surfactant Charge and of Surfactant Concentration. Antioxidants (Basel) 2023; 12:1158. [PMID: 37371888 PMCID: PMC10294913 DOI: 10.3390/antiox12061158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
Charged interfaces may play an important role in the fate of chemical reactions. Alterations in, for instance, the interfacial acidity of emulsions induced by the charge of the surfactant head group and associated counterions may change the ionization status of antioxidants, modifying their effective concentrations. The chemical reactivity between interfacial reactants and charged species of opposite charge (protons, metallic ions, etc.) is usually interpreted in terms of pseudophase ion-exchange models, treating the distribution of charged species in terms of partitioning and ion exchange. Here, we focus on analyzing the effects of charged interfaces on the oxidative stability of soybean oil-in-water (o/w) emulsions prepared with anionic (sodium dodecyl sulfate, SDS), cationic (cetyltrimethylammonium bromide, CTAB) and neutral (Tween 20) surfactants, and some of their mixtures, in the presence and absence of δ-tocopherol (δ-TOC). We have also determined the effective concentrations of δ-TOC in the oil, interfacial and aqueous regions of the intact emulsions. In the absence of δ-TOC, the relative oxidative stability order was CTAB < TW20 ~ TW20/CTAB < SDS. Surprisingly, upon the addition of δ-TOC, the relative order was SDS ≈ TW20 << TW20/CTAB < CTAB. These apparently surprising results can be rationalized in terms of the nice correlation that exists between the relative oxidative stability and the effective interfacial concentrations of δ-TOC in the various emulsions. The results emphasize the importance of considering the effective interfacial concentrations of antioxidants in interpreting their relative efficiency in emulsions.
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Affiliation(s)
| | - Sonia Losada-Barreiro
- Departamento Química-Física, Facultad de Química, Universidade de Vigo, 36310 Vigo, Spain (C.B.-D.)
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2
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Development of Novel Lipid-Based Formulations for Water-Soluble Vitamin C versus Fat-Soluble Vitamin D3. BIOENGINEERING (BASEL, SWITZERLAND) 2022; 9:bioengineering9120819. [PMID: 36551025 PMCID: PMC9774173 DOI: 10.3390/bioengineering9120819] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022]
Abstract
The aim of this study was to develop a facile and novel lipid-based formulation of vitamin C and vitamin D3. Liposomes loaded with vitamin C and D3 were characterized using transmission electron microscopy (TEM) and zeta potential measurements for evaluating morphology, particle size and physical stability. HPLC was employed to quantify the content of vitamin C and vitamin D3 in their liposomal forms. The UHPLC analysis of the lipid-based vitamin formulation is an easy and rapid method for the characterization as well as the quantification of all components. In addition, encapsulation efficiency, vitamin loading and stability analysis were performed by the UHPLC method, in order to evaluate the reliability of the optimized lipid-based formulation. The TEM results provided key support for the core type of liposome structure in the formulations, whereas the HPLC results indicated that the liposomal vitamin C and D3 systems were homogeneous, and did not undergo phase separation. Taken together, the results demonstrate that liposomal encapsulated vitamins (vitamin C and D3) possess a unilamellar vesicle morphology with uniform particle size, despite differences in the hydrophile-lipophile profiles of the vitamins. The highly efficient encapsulation properties of such liposomal constructs are proposed to contribute to enhanced vitamin bioavailability.
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3
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Bravo-Díaz C. Advances in the control of lipid peroxidation in oil-in-water emulsions: kinetic approaches †. Crit Rev Food Sci Nutr 2022; 63:6252-6284. [PMID: 35104177 DOI: 10.1080/10408398.2022.2029827] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Large efforts have been, and still are, devoted to minimize the harmful effects of lipid peroxidation. Much of the early work focused in understanding both the lipid oxidation mechanisms and the action of antioxidants in bulk solution. However, food-grade oils are mostly present in the form of oil-in-water emulsions, bringing up an increasing complexity because of the three-dimensional interfacial region. This review presents an overview of the kinetic approaches employed in controlling the oxidative stability of edible oil-in-water emulsions and of the main outcomes, with particular emphasis on the role of antioxidants and on the kinetics of the inhibition reaction. Application of physical-organic chemistry methods, such as the pseudophase models to investigate antioxidant partitioning, constitute a remarkable example on how kinetic methodologies contribute to model chemical reactivity in multiphasic systems and to rationalize the role of interfaces, opening new opportunities for designing novel antioxidants with tailored properties and new prospects for modulating environmental conditions in attempting to optimize their efficiency. Here we will summarize the main kinetic features of the inhibition reaction and will discuss on the main factors affecting its rate, including the determination of antioxidant efficiencies from kinetic profiles, structure-reactivity relationships, partitioning of antioxidants and concentration effects.
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Affiliation(s)
- Carlos Bravo-Díaz
- Facultad de Ciencias, Departamento de Química Física, Universidad de Vigo, Vigo, Spain
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4
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Costa M, Losada-Barreiro S, Paiva-Martins F, Bravo-Díaz C. Effects of Surfactant Volume Fraction on the Antioxidant Efficiency and on The Interfacial Concentrations of Octyl and Tetradecyl p-Coumarates in Corn Oil-in-Water Emulsions. Molecules 2021; 26:molecules26196058. [PMID: 34641602 PMCID: PMC8512349 DOI: 10.3390/molecules26196058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/29/2021] [Accepted: 10/02/2021] [Indexed: 11/23/2022] Open
Abstract
Surfactants have been used for decades in the food industry for the preparation of lipid-based emulsified food stuffs. They play two main roles in the emulsification processes: first they decrease the interfacial tension between the oil and water, facilitating droplet deformation and rupture; second, they reduce droplet coalescence by forming steric barriers. However, addition of surfactants to binary oil-water mixtures also brings up the formation of three-dimensional interfacial layers, surrounding each emulsion droplet, that significantly alter chemical reactivity. This is the case, for instance, in the inhibition reaction between antioxidants and the lipid radicals formed in the course of the spontaneous oxidation reaction of unsaturated lipids, which are commonly employed in the preparation of food-grade emulsions. The rate of the inhibition reaction depends on the effective concentrations of antioxidants, which are mostly controlled by the amount of surfactant employed in the preparation of the emulsion. In this work, we analyze the effects of the surfactant Tween 20 on the oxidative stability and on the effective concentrations of two model antioxidants derived from cinnamic acid, determining their interfacial concentrations in the intact emulsions to avoid disrupting the existing equilibria and biasing results. For this purpose, a recently developed methodology was employed, and experimental results were interpreted on the grounds of a pseudophase kinetic model.
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Affiliation(s)
- Marlene Costa
- REQUIMTE/LAQV, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal; (M.C.); (F.P.-M.)
| | - Sonia Losada-Barreiro
- Departamento de Química-Física, Facultad de Química, Universidade de Vigo, 36310 Vigo, Spain;
| | - Fátima Paiva-Martins
- REQUIMTE/LAQV, Department of Chemistry and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal; (M.C.); (F.P.-M.)
| | - Carlos Bravo-Díaz
- Departamento de Química-Física, Facultad de Química, Universidade de Vigo, 36310 Vigo, Spain;
- Correspondence:
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5
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Łukawski M, Dałek P, Borowik T, Foryś A, Langner M, Witkiewicz W, Przybyło M. New oral liposomal vitamin C formulation: properties and bioavailability. J Liposome Res 2019; 30:227-234. [PMID: 31264495 DOI: 10.1080/08982104.2019.1630642] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Vitamin C is the exogenous compound necessary for a variety of metabolic processes; therefore, the efficient delivery is critical for the maintenance of body homeostasis. Vitamin C pharmacokinetics and low quantities in processed foodstuff, necessitates its continuous supplementation. In the paper, we present the new liposomal formulation of vitamin C free of harmful organic solvents. The formulation was quantitatively characterized with respect to its chemically composition and nano-structuring. The vitamin C accessibility to cells from the formulation was evaluated using evidence derived from experiments performed on cell cultures. Finally, the enhanced bioavailability of vitamin C from the formulation was demonstrated in the medical experiment.
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Affiliation(s)
- Maciej Łukawski
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wrocław, Poland
| | - Paulina Dałek
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wrocław, Poland.,Lipid Systems Ltd, Wrocław, Poland
| | | | - Aleksander Foryś
- Centre of Polymer and Carbon Materials, Polish Academy of Sciences, Zabrze, Poland
| | - Marek Langner
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wrocław, Poland.,Lipid Systems Ltd, Wrocław, Poland
| | - Wojciech Witkiewicz
- Research and Development Centre, Specialized Hospital in Wrocław, Wrocław, Poland
| | - Magdalena Przybyło
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wrocław, Poland.,Lipid Systems Ltd, Wrocław, Poland
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6
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Dispersed phase volume fraction, weak acids and Tween 80 in a model emulsion: Effect on the germination and growth of Bacillus weihenstephanensis KBAB4 spores. Food Res Int 2018; 109:288-297. [PMID: 29803452 DOI: 10.1016/j.foodres.2018.04.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 04/12/2018] [Accepted: 04/12/2018] [Indexed: 11/21/2022]
Abstract
In foodstuffs, physico-chemical interactions and/or physical constraints between spores, inhibitors and food components may exist. Thus, the objective of this study was to investigate such interactions using a model emulsion as a microbial medium in order to improve bacterial spore control with better knowledge of the interactions in the formulation. Emulsions were prepared with hexadecane mixed with nutrient broth using sonication and were stabilized by Tween 80 and Span 80. The hexadecane ratio was either 35% (v/v) or 50% (v/v) and each emulsion was studied in the presence of organic acid (acetic, lactic or hexanoic) at two pH levels (5.5 and 6). Self-diffusion coefficients of emulsion components and the organic acids were measured by Pulsed Field Gradient-Nuclear Magnetic Resonance (PFG-NMR). The inhibition effect on the spore germination and cell growth of Bacillus weihenstephanensis KBAB4 was characterized by the measure of the probability of growth using the most probable number methodology, and the measure of the time taken for the cells to germinate and grow using a single cell Bioscreen® method and using flow cytometry. The inhibition of spore germination and growth in the model emulsion depended on the dispersed phase volume fraction and the pH value. The effect of the dispersed phase volume fraction was due to a combination of (i) the lipophilicity of the biocide, hexanoic acid, that may have had an impact on the distribution of organic acid between hexadecane and the aqueous phases and (ii) the antimicrobial activity of the emulsifier Tween 80 detected at the acidic pH value. The interface phenomena seemed to have a major influence. Future work will focus on the exploration of these phenomena at the interface.
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7
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Bravo‐Díaz C, Romsted LS, Losada‐Barreiro S, Paiva‐Martins F. Using a pseudophase model to determine AO distributions in emulsions: Why dynamic equilibrium matters. EUR J LIPID SCI TECH 2017. [DOI: 10.1002/ejlt.201600277] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Carlos Bravo‐Díaz
- Facultad de Química, Dpto. Química‐FísicaUniversidad de VigoVigoSpain
| | - Laurence S. Romsted
- Department of Chemistry and Chemical BiologyRutgers, the State University of New JerseyNew JerseyNew Jersey
| | - Sonia Losada‐Barreiro
- Facultad de Química, Dpto. Química‐FísicaUniversidad de VigoVigoSpain
- REQUIMTE‐LAQV, Departamento de Química e Bioquímica, Faculdade de CiênciasUniversidade do PortoPortoPortugal
| | - Fátima Paiva‐Martins
- REQUIMTE‐LAQV, Departamento de Química e Bioquímica, Faculdade de CiênciasUniversidade do PortoPortoPortugal
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Almeida J, Losada-Barreiro S, Costa M, Paiva-Martins F, Bravo-Díaz C, Romsted LS. Interfacial Concentrations of Hydroxytyrosol and Its Lipophilic Esters in Intact Olive Oil-in-Water Emulsions: Effects of Antioxidant Hydrophobicity, Surfactant Concentration, and the Oil-to-Water Ratio on the Oxidative Stability of the Emulsions. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:5274-5283. [PMID: 27157893 DOI: 10.1021/acs.jafc.6b01468] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We determined the interfacial molarities of the antioxidants, AOs, hydroxytyrosol (HT), and HT fatty acid esters with chain lengths of 1 to 16 carbons in intact olive oil/water/Tween 20 emulsions. The results were compared with chain length effects on the oxidative stability of the same emulsions, and a direct correlation was established. Both (AOI) molarities (varying 50-250 times greater than the stoichiometric 3.5 × 10(-3) M AO concentration) and antioxidant efficiencies show similar parabola-like dependences on AO chain length with a maximum at C8, consistent with the "cut-off" effect often observed at longer chain lengths. Results should aid in understanding the complex structure-reactivity relationships between AO efficiencies in emulsified systems and their hydrophobilic-hydrophobic balance.
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Affiliation(s)
- João Almeida
- REQUIMTE-LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , 4169-007 Porto, Portugal
| | - Sonia Losada-Barreiro
- REQUIMTE-LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , 4169-007 Porto, Portugal
- Universidad de Vigo , Fac. Química, Dpto Química Física, 36200 Vigo, Spain
| | - Marlene Costa
- REQUIMTE-LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , 4169-007 Porto, Portugal
| | - Fátima Paiva-Martins
- REQUIMTE-LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , 4169-007 Porto, Portugal
| | - Carlos Bravo-Díaz
- Universidad de Vigo , Fac. Química, Dpto Química Física, 36200 Vigo, Spain
| | - Laurence S Romsted
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , Piscataway, New Jersey 08854, United States
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9
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Costa M, Losada-Barreiro S, Paiva-Martins F, Bravo-Díaz C. Optimizing the efficiency of antioxidants in emulsions by lipophilization: tuning interfacial concentrations. RSC Adv 2016. [DOI: 10.1039/c6ra18282h] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Antioxidant efficiencies in emulsions can be optimized by tailoring interfacial concentrations.
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Affiliation(s)
- Marlene Costa
- REQUIMTE-LAQV
- Departamento de Química e Bioquímica
- Faculdade de Ciências. Universidade Do Porto
- Portugal
| | - Sonia Losada-Barreiro
- REQUIMTE-LAQV
- Departamento de Química e Bioquímica
- Faculdade de Ciências. Universidade Do Porto
- Portugal
- Universidad de Vigo
| | - Fátima Paiva-Martins
- REQUIMTE-LAQV
- Departamento de Química e Bioquímica
- Faculdade de Ciências. Universidade Do Porto
- Portugal
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10
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Galan A, Losada-Barreiro S, Bravo-Díaz C. A Physicochemical Study of the Effects of Acidity on the Distribution and Antioxidant Efficiency of Trolox in Olive Oil-in-Water Emulsions. Chemphyschem 2015; 17:296-304. [PMID: 26592178 DOI: 10.1002/cphc.201500882] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Indexed: 11/08/2022]
Abstract
The efficiency of antioxidants to inhibit the oxidation of lipid-based emulsions depends on several factors including their nature and their concentration at the reaction site. Here, we have analyzed the effects of acidity and of surfactant concentration on the distribution and efficiency of the vitamin E analog Trolox (TR) in stripped olive oil-in-water emulsions stabilized with Tween 20. The distribution was assessed in the intact emulsions by employing a kinetic method that exploits the reaction between the hydrophobic 4-hexadecylbenzenediazonium ions and TR. Kinetic results are interpreted on the grounds of the pseudophase model. The effects of TR on the oxidative stability of the emulsion were determined at different pH values by monitoring the formation of conjugated dienes over time. The results show that the efficiency of TR increases upon increasing pH even though its concentration in the interfacial region decreases.
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Affiliation(s)
- Anna Galan
- Departamento de Química Física, Universidad de Vigo, Rua das Abelleiras S/N, 36200 Vigo, Pontevedra, Spain
| | - Sonia Losada-Barreiro
- Departamento de Química Física, Universidad de Vigo, Rua das Abelleiras S/N, 36200 Vigo, Pontevedra, Spain.
| | - Carlos Bravo-Díaz
- Departamento de Química Física, Universidad de Vigo, Rua das Abelleiras S/N, 36200 Vigo, Pontevedra, Spain
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11
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Bravo-Díaz C, Romsted LS, Liu C, Losada-Barreiro S, Pastoriza-Gallego MJ, Gao X, Gu Q, Krishnan G, Sánchez-Paz V, Zhang Y, Dar AA. To Model Chemical Reactivity in Heterogeneous Emulsions, Think Homogeneous Microemulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:8961-8979. [PMID: 25805058 DOI: 10.1021/acs.langmuir.5b00112] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Two important and unsolved problems in the food industry and also fundamental questions in colloid chemistry are how to measure molecular distributions, especially antioxidants (AOs), and how to model chemical reactivity, including AO efficiency in opaque emulsions. The key to understanding reactivity in organized surfactant media is that reaction mechanisms are consistent with a discrete structures-separate continuous regions duality. Aggregate structures in emulsions are determined by highly cooperative but weak organizing forces that allow reactants to diffuse at rates approaching their diffusion-controlled limit. Reactant distributions for slow thermal bimolecular reactions are in dynamic equilibrium, and their distributions are proportional to their relative solubilities in the oil, interfacial, and aqueous regions. Our chemical kinetic method is grounded in thermodynamics and combines a pseudophase model with methods for monitoring the reactions of AOs with a hydrophobic arenediazonium ion probe in opaque emulsions. We introduce (a) the logic and basic assumptions of the pseudophase model used to define the distributions of AOs among the oil, interfacial, and aqueous regions in microemulsions and emulsions and (b) the dye derivatization and linear sweep voltammetry methods for monitoring the rates of reaction in opaque emulsions. Our results show that this approach provides a unique, versatile, and robust method for obtaining quantitative estimates of AO partition coefficients or partition constants and distributions and interfacial rate constants in emulsions. The examples provided illustrate the effects of various emulsion properties on AO distributions such as oil hydrophobicity, emulsifier structure and HLB, temperature, droplet size, surfactant charge, and acidity on reactant distributions. Finally, we show that the chemical kinetic method provides a natural explanation for the cut-off effect, a maximum followed by a sharp reduction in AO efficiency with increasing alkyl chain length of a particular AO. We conclude with perspectives and prospects.
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Affiliation(s)
- Carlos Bravo-Díaz
- Universidade de Vigo , Facultad de Química, Departamento Química Física, 36200, Vigo, Spain
| | - Laurence Stuart Romsted
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08854, United States
| | - Changyao Liu
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08854, United States
| | - Sonia Losada-Barreiro
- Universidade de Vigo , Facultad de Química, Departamento Química Física, 36200, Vigo, Spain
| | | | - Xiang Gao
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08854, United States
| | - Qing Gu
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08854, United States
| | - Gunaseelan Krishnan
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08854, United States
| | - Verónica Sánchez-Paz
- Universidade de Vigo , Facultad de Química, Departamento Química Física, 36200, Vigo, Spain
| | - Yongliang Zhang
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08854, United States
| | - Aijaz Ahmad Dar
- Department of Chemistry, University of Kashmir , Hazratbal, Srinagar, J&K India
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Losada-Barreiro S, Sánchez-Paz V, Bravo-Díaz C. Transfer of antioxidants at the interfaces of model food emulsions: distributions and thermodynamic parameters. Org Biomol Chem 2015; 13:876-85. [PMID: 25408193 DOI: 10.1039/c4ob02058h] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Knowledge on the driving force for the hydrophobic effect that partitions antioxidants (AOs) between the oil (O), aqueous (W) and interfacial (I) regions of food emulsions is crucial to predict their efficiency in inhibiting lipid oxidation and to preserve the organoleptic properties of lipid-based foods. Here, we have investigated the effects of temperature and surfactant volume fraction (ΦI) on the distribution of two representative AOs, the water insoluble α-tocopherol (TOC) and the oil insoluble caffeic acid (CA), in a model food emulsion composed of stripped corn oil, acidic water and the nonionic surfactant Tween 20. The distribution of the AOs is assessed in the intact emulsions by employing a well-established kinetic method based on the reaction between a hydrophobic arenediazonium ion and the AOs. The variations of the observed rate constant, kobs, with ΦI are interpreted on the grounds of the pseudophase kinetic model, which provides values for the interfacial rate constant kI and the partition constants between the aqueous-interfacial (P) and oil-interfacial (P) regions of the emulsions. From the variations of P, P and kI at a series of temperatures, we determined the Gibbs free energy, enthalpy and entropy values for the transfer of CA from the water to the interfacial (W → I) region and of TOC from the oil to the interfacial (O → I) regions of the emulsions, and the activation parameters for the reaction in the interfacial region. Activation energy values are in line with those expected for a bimolecular reaction. Results show that the W → I and O → I transfer processes are spontaneous and entropy driven.
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13
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Losada-Barreiro S, Bravo-Díaz C, Romsted LS. Distributions of phenolic acid antioxidants between the interfacial and aqueous regions of corn oil emulsions: Effects of pH and emulsifier concentration. EUR J LIPID SCI TECH 2015. [DOI: 10.1002/ejlt.201400507] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Carlos Bravo-Díaz
- Departamento Química Física, Facultad de Química; Universidad de Vigo; Vigo Spain
| | - Laurence S. Romsted
- Department of Chemistry and Chemical Biology; Rutgers, the State University of New Jersey; NJ USA
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14
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Berton-Carabin CC, Ropers MH, Genot C. Lipid Oxidation in Oil-in-Water Emulsions: Involvement of the Interfacial Layer. Compr Rev Food Sci Food Saf 2014. [DOI: 10.1111/1541-4337.12097] [Citation(s) in RCA: 362] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
| | | | - Claude Genot
- INRA; UR1268 Biopolymères Interactions Assemblages; F-44316 Nantes France
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15
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Sienkiewicz A, Szymula M, Narkiewicz-Michalek J, Bravo-Díaz C. Formation of diazohydroxides ArN2
OH in aqueous acid solution: polarographic determination of the equilibrium constant K
R
for the reaction of 4-substituted arenediazonium ions with H2
O. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3194] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Marta Szymula
- Faculty of Chemistry; Maria Curie-Skłodowska University; Lublin Poland
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17
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Effects of Acidity, Temperature and Emulsifier Concentration on the Distribution of Caffeic Acid in Stripped Corn and Olive Oil-in-Water Emulsions. J AM OIL CHEM SOC 2013. [DOI: 10.1007/s11746-013-2309-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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18
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Losada Barreiro S, Bravo-Díaz C, Paiva-Martins F, Romsted LS. Maxima in antioxidant distributions and efficiencies with increasing hydrophobicity of gallic acid and its alkyl esters. The pseudophase model interpretation of the "cutoff effect". JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:6533-6543. [PMID: 23701266 DOI: 10.1021/jf400981x] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Antioxidant (AO) efficiencies are reported to go through maxima with increasing chain length (hydrophobicity) in emulsions. The so-called "cutoff" after the maxima, indicating a decrease in efficiency, remains unexplained. This paper shows, for gallic acid (GA) and propyl, octyl, and lauryl gallates (PG, OG, and LG, respectively), that at any given volume fraction of emulsifier, the concentrations of antioxidants in the interfacial region of stripped corn oil emulsions and their efficiency order follow PG > GA > OG > LG. These results provide clear evidence that an AO's efficiency correlates with its fraction in the interfacial region. AO distributions were obtained in intact emulsions by using the pseudophase kinetic model to interpret changes in observed rate constants of the AOs with a chemical probe, and their efficiencies were measured by employing the Schaal oven test. The model provides a natural explanation for the maxima with increasing AO hydrophobicity.
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Affiliation(s)
- Sonia Losada Barreiro
- Departamento Química Física, Facultad Química, Universidad de Vigo, 36200 Vigo, Spain
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19
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|