Here we have applied the formalism of the pseudophase kinetic model to analyze the reactivity of 4-hexadecylbenzenediazonium, 16-ArN2+, ions with the antioxidants octyl gallate (OG) and lauryl gallate (LG) in emulsions composed of octane, acidic water and hexaetyleneglycol monododecyl ether, C12E6 [...]
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 [...]
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 [...]
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 [...]
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 [...]
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 [...]
In this work, we have evaluated the effects of emulsifier concentration on the distribution of catechol (1,2-dihydroxybenzene, CAT) in food-grade emulsions composed of stripped corn oil, acidic water, and Tween 20. Auxiliary experiments in binary stripped corn oil–water mixtures, in the absence of emulsifier, showed that CAT is both oil and water soluble (partition constant math formula = 0.34) [...]
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 [...]
We evaluated the effects of oil type, oil to water ratio, emulsifier concentration, acidity, and temperature on the distribution of caffeic acid, CA, in emulsions composed of stripped olive and corn oils, acidic water, and Tween 20. CA mainly distributes between the water and interfacial regions because it is sparingly soluble in oils, as demonstrated by auxiliary partitioning experiments in the absence of an emulsifier [...]
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) [...]