Control of antioxidant efficiency of chlorogenates in emulsions: modulation of antioxidant interfacial concentrations. Journal of the Science of Food and Agriculture

05 January 2019

Journal of the Science of Food and Agriculture

Sonia Losada-Barreiro*a, Fátima Paiva-Martinsb, Marlene Costab, Mafalda Meireles, Carlos Bravo-Díaza, Luis S.Monteiro

Autor affilations:

*Corresponding authors
aDepartanento de Química Física, Universidad de Vigo, Spain
bREQUIMTE-LAQV, Departamento de Química e Bioquímica. Faculdade de Ciências. Universidade do Porto., 4169-007 Porto, Portugal

Abstract

Background Controlling the interfacial concentrations of antioxidants (AOs) in O/W emulsions can be regarded as an unique approach for increasing the efficiency of AOs in inhibiting the oxidation of lipids. Classical methods to determine the AO distribution in binary systems cannot be employed and their distribution needs to be assessed in the intact emulsion. Results We have employed a well‐established kinetic method to determine the distribution of a homologous series of AOs derived of chlorogenic acid in olive oil‐in‐water emulsions and analyse the effects of AO hydrophobicity on their distributions and their efficiencies. Results indicate that the variations in the efficiency of chlorogenates in emulsions are due to differences in their interfacial concentrations. Their interfacial concentrations, (AOI), were much higher (20‐150‐fold) than their stoichiometric concentrations. On the other hand, their concentrations in the oil region were 1.5‐0.1 fold. Results also show the complex effect of the oil to water ratio employed in the preparation of the emulsions on the (AOI) values. Conclusion Results highlight the key role of the interfacial region and of its composition (interfacial AO molarity, emulsifier concentration, oil to water ratio) in interpreting the efficiency of AOs in inhibiting lipid oxidation in emulsions. Thus, a careful modulation of these parameters is necessary to ensure optimum AO efficiency.