Modulating the interfacial concentration of gallates to improve the oxidative stability of fish oil-in-water emulsions

Posted on 1 June, 201814 February, 2019 by antiox@uvigo.es

The distributions of some gallates were determined in intact fish oil emulsions. % gallates at the interface increases upon increasing surfactant volume fraction ΦI. On the contrary, their interfacial concentrations decrease upon increasing ΦI. Their efficiencies correlate directly with the gallate interfacial concentrations. Butyl and octyl gallates were the most suitable to protect the fish emulsions. [...]

Partitioning and antioxidative effect of protocatechuates in soybean oil emulsions: relevance of emulsifier concentration

Posted on 20 April, 201719 July, 2017 by antiox@uvigo.es

Distributions of a homologous series of protocatechuic acid (PCA) derivatives of increasing lipophilicity were determined in stripped soybean oil-in-water emulsions and compared with their antioxidant (AO) efficiencies. The distribution was determined by employing a recently developed a kinetic method, based on the reaction between the hydrophobic 4-hexadecylbenzenediazonium ions (16-ArN2+) [...]

Physical evidence that the variations in the efficiency of homologous series of antioxidants in emulsions are due to differences in their partitioning

Posted on 13 January, 201710 May, 2017 by antiox@uvigo.es

The relationships between the hydrophilic-lipophilic balance (HLB) of antioxidants (AOs) and their distributions and efficiencies in emulsions are not fully understood. Recent reports indicate that, for series of homologous antioxidants of different hydrophobicity, the variation of their efficiency with the HLB of the AO increases with the alkyl chain length up to a maximum (C3 -C8ester) followed by a decrease [...]

Distributions of phenolic acid antioxidants between the interfacial and aqueous regions of corn oil emulsions: effects of acidity and emulsifier concentration

Posted on 17 July, 201514 May, 2017 by antiox@uvigo.es

The oxidative stability of emulsions depends on acidity because pH may affect, among other things, the concentration of antioxidants (AOs) at the reaction site. Here we investigated the effects of pH on the partition constant, PWI, and the distribution of two phenolic acid AOs, gallic (GA) and caffeic (CA), between the aqueous (W) and interfacial (I) regions, in emulsions of 1:9 (vol:vol) corn oil/acidic water [...]

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

Posted on 15 May, 201511 May, 2017 by antiox@uvigo.es

Recently published results for a series of homologous antioxidants, AOs, of increasing alkyl chain length show a maximum in AO efficiency followed by a significant decrease for the more hydrophobic AOs, typically called the "cut-off" effect. Here we demonstrate that in olive oil emulsions both antioxidant efficiencies [...]

To model chemical reactivity in heterogeneous emulsions: think homogeneous microemulsions

Posted on 25 March, 201514 May, 2017 by antiox@uvigo.es

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 [...]

Transfer of antioxidants at the interfaces of model food emulsions: distributions and thermodynamic parameters

Posted on 21 January, 201514 May, 2017 by antiox@uvigo.es

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 [...]

Distribution and antioxidant efficiency of resveratrol in stripped corn oil-in water emulsions

Posted on 4 April, 201414 May, 2017 by antiox@uvigo.es

We investigated the effects of resveratrol (RES) on the oxidative stability of emulsions composed of stripped corn oil, acidic water and Tween 20 and determined its distribution in the intact emulsions by employing a well-established kinetic method. The distribution of RES is described by two partition constants, that between the oil-interfacial region, POI, and that between the aqueous and interfacial region, PWI [...]

Influence of temperature on the distribution of catechin in corn oil-in water emulsions and some relevant thermodynamic parameters

Posted on 25 March, 201414 May, 2017 by antiox@uvigo.es

We investigated the effects of increasing temperature and emulsifier volume fraction (ΦI) on the distribution of catechin (CAT) in stripped corn oil-in-water emulsions. We also estimated relevant thermodynamic parameters for the transfer of CAT from the aqueous to the interfacial region because CAT is sparingly soluble in corn oil and mainly distributes between the aqueous and interfacial regions of emulsions [...]

Maxima in antioxidant distributions and efficiencies with increasing hydrophobicity of gallic acid and its alkyl esters. The pseudophase model interpretation of the “cutoff effect”

Posted on 23 May, 201314 May, 2017 by antiox@uvigo.es

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) [...]