A direct correlation between the antioxidant efficiencies of caffeic acid and its alkyl esters and their concentrations in the interfacial region of olive oil emulsions. The pseudophase model interpretation of the “cut-off” effect

Costa, Marlene; Losada‐Barreiro, Sonia; Paiva‐Martins, Fátima; Romsted, Laurence S.

doi:10.1016/j.foodchem.2014.10.016

Cited by 86 publications

(173 citation statements)

References 30 publications

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“…Note that in Figure 8A propyl gallate (PG) has the highest percentage in the interfacial region, and in Figure 8B it slows oxidation to the greatest extent (compare curves at 0.1% CD, conjugated dienes). Figure 9 shows a similar set of results for caffeic acid and some of its esters, 69 although the data is represented differently. Figure 9A,B shows the bulk efficiency results, but this time the greatest efficiency is for the octyl gallate, OG.…”

Section: Effect Of Ao Hydrophilic−lipophilic Balance (Hlb) On Ao Ementioning

confidence: 87%

“…12 In 2013 and 2015, we reported maxima in AO efficiency in nonionic emulsions for two different AOs and their esters of various chain lengths (Chart 1) gallic and caffeic acids and their alkyl esters. 34,69 We used the chemical kinetic method to determine P O I and P W I of the acids and alkyl esters of these AOs. The results show that with increasing alkyl chain length P W I increases, P O I and %AO I go through maxima with increasing chain length, and these maxima match the maximum in the measured AO efficiency ( Figure 8A,B).…”

Section: Effect Of Ao Hydrophilic−lipophilic Balance (Hlb) On Ao Ementioning

confidence: 99%

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To Model Chemical Reactivity in Heterogeneous Emulsions, Think Homogeneous Microemulsions

et al. 2015

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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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Section: Effect Of Ao Hydrophilic−lipophilic Balance (Hlb) On Ao Ementioning

confidence: 87%

Section: Effect Of Ao Hydrophilic−lipophilic Balance (Hlb) On Ao Ementioning

confidence: 99%

To Model Chemical Reactivity in Heterogeneous Emulsions, Think Homogeneous Microemulsions

et al. 2015

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“…Using a broad range of homologous series of antioxidants in dispersed lipid models and cultured cells, it has been demonstrated that the antioxidant activity increases progressively with increasing chain length up to a critical point, beyond which the activity of the compounds decreases (Figure 4). Since its first mention (Laguerre et al 2009), this cut-off effect for antioxidants has been the subject of extensive research in lipid dispersions (Alemán et al 2015;Costa et al 2015;Laguerre et al 2010;Lee et al 2013;Losada-Barreiro et al 2013;Medina et al 2009;Panya et al 2012;Sørensen et al 2012Sørensen et al , 2014Sørensen et al , 2015 and cellular models , Laguerre et al 2011, Munoz-Marin et al 2013) as well as of review articles (Laguerre et al 2013a(Laguerre et al ,b, 2015Shahidi & Zhong 2011;Zhao et al 2015). Table 1 gives some examples of the experimental confirmations of the occurrence of a cut-off effect.…”

Section: Figurementioning

confidence: 99%

Mass Transport Phenomena in Lipid Oxidation and Antioxidation

Laguerre

Bily

Roller³

et al. 2017

Annu. Rev. Food Sci. Technol.

133

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In lipid dispersions, the ability of reactants to move from one lipid particle to another is an important, yet often ignored, determinant of lipid oxidation and its inhibition by antioxidants. This review describes three putative interparticle transfer mechanisms for oxidants and antioxidants: (a) diffusion, (b) collision-exchange-separation, and (c) micelle-assisted transfer. Mechanism a involves the diffusion of molecules from one particle to another through the intervening aqueous phase. Mechanism b involves the transfer of molecules from one particle to another when the particles collide with each other. Mechanism c involves the solubilization of molecules in micelles within the aqueous phase and then their transfer between particles. During lipid oxidation, the accumulation of surface-active lipid hydroperoxides (LOOHs) beyond their critical micelle concentration may shift their mass transport from the collision-exchange-separation pathway (slow transfer) to the micelle-assisted mechanism (fast transfer), which may account for the transition from the initiation to the propagation phase. Similarly, the cutoff effect governing antioxidant activity in lipid dispersions may be due to the fact that above a certain hydrophobicity, the transfer mechanism for antioxidants changes from diffusion to collision-exchange-separation. This hypothesis provides a simple model to rationalize the design and formulation of antioxidants and dispersed lipids.

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“…This is because compounds 1-6 have some structural analogies with 363 many antioxidant "phenolipids", like the esters of caffeic, gallic or rosmaric acid (Laguerre et al 364 2009;Laguerre et al, 2010;Heins et al, 2007;Barreiro et al, 2013;Costa et al, 2015). In both 365 cases, a lipophilic chain of variable length is grafted to the reacting fragment, a TEMPO group in 366 probes 1-6, or a phenolic group in many "phenolipids", generating two moieties of close 367 hydrophobicities that may compete for the hydrophobic core in a micellar system or an oil 368 emulsion.…”

Section: Introduction 42 43mentioning

confidence: 99%

Location of TEMPO derivatives in micelles: subtle effect of the probe orientation

et al. 2016

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A direct correlation between the antioxidant efficiencies of caffeic acid and its alkyl esters and their concentrations in the interfacial region of olive oil emulsions. The pseudophase model interpretation of the “cut-off” effect

Cited by 86 publications

References 30 publications

To Model Chemical Reactivity in Heterogeneous Emulsions, Think Homogeneous Microemulsions

To Model Chemical Reactivity in Heterogeneous Emulsions, Think Homogeneous Microemulsions

Mass Transport Phenomena in Lipid Oxidation and Antioxidation

Location of TEMPO derivatives in micelles: subtle effect of the probe orientation

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