Impact of edible surfactants on the oxidation of olive oil in water-in-oil emulsions

In this paper we study the impact of edible surfactants on the oxidation of olive oil in water-in-oil emulsions. Different sorbitan fatty acid esters (Span 20, sorbitan monolaurate; Span 80, sorbitan monooleate; Span 85, sorbitan trioleate) were used to prepare water-in-olive oil emulsions, which were then oxidized by UV light. The oxidation was monitored by measuring the peroxide value and by calculating the droplet size distribution at different oxidation times. The results obtained from ternary emulsions were compared to Span-olive oil and water-olive oil binary systems in order to evaluate the contribution of each component in the oxidation of emulsified olive oils. The experimental data show that there is a link between the oxidative stability and emulsion stability. Furthermore, the effectiveness of Spans in stabilizing the emulsified olive oils were related to their chemical structure and so to their ability to interact with hydroperoxides. (C) 2006 Elsevier Ltd. All rights reserved.