title: Maxima in antioxidant distributions and efficiencies with increasing hydrophobicity of gallic acid and its alkyl esters. The pseudophase model interpretation of the "cutoff effect".
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.
authors.affiliation: Departamento Química Física, Facultad Química, Universidad de Vigo, 36200 Vigo, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Losada Barreiro
authors.forename: Carlos
authors.initials: C
authors.lastname: Bravo-Díaz
authors.forename: Fátima
authors.initials: F
authors.lastname: Paiva-Martins
authors.forename: Laurence S
authors.initials: LS
authors.lastname: Romsted
mesh_terms: D000478:Alkylation; D000975:Antioxidants / Q000737:chemistry*; D003314:Corn Oil / Q000737:chemistry; D045703:Emulsifying Agents / Q000737:chemistry*; D004655:Emulsions; D004952:Esters; D005503:Food Additives / Q000737:chemistry*; D005520:Food Preservatives / Q000737:chemistry*; D005707:Gallic Acid / Q000737:chemistry*; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008956:Models, Chemical; D000069463:Olive Oil; D010938:Plant Oils / Q000737:chemistry
chemical_list: D000975:Antioxidants; D045703:Emulsifying Agents; D004655:Emulsions; D004952:Esters; D005503:Food Additives; D005520:Food Preservatives; D000069463:Olive Oil; D010938:Plant Oils; D005707:Gallic Acid; D003314:Corn Oil