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

Sonia Losada Barreiro, Carlos Bravo-Díaz, Fátima Paiva-Martins, Laurence S. Romsted

Research output: Contribution to journalArticlepeer-review

57 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)6533-6543
Number of pages11
JournalJournal of agricultural and food chemistry
Volume61
Issue number26
DOIs
StatePublished - Jul 3 2013

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

Keywords

  • antioxidant distributions
  • antioxidant efficiency
  • arenediazonium ions
  • cutoff effect
  • emulsions
  • polar paradox

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