Lipid oxidation products in model food emulsions: do they stay in or leave droplets, that's the question

Lipid oxidation is a major factor limiting the shelf life of food and other emulsion products. In this work, we explore which lipid oxidation products may transfer between oil droplets in model food emulsions stabilized by excess amounts of surfactant, and whether this affects the overall reaction. No significant differences in con-centrations of triglyceride-bound hydroperoxides were found before and after mixing 'clean' oil droplets with pre-oxidized ones. Shorter and more hydrophilic lipid oxidation products, such as 4-hydroperoxy-2-nonenal and 2,4-decadienal, were found to equilibrate between oil droplets within 30 min. Adding exogenous 4-hydroperoxy-2-nonenal to an emulsion led to overall higher lipid oxidation values, although this effect was not systematic nor instantaneous. Therefore, it may be questioned whether transfer and subsequent initiation are always relevant for oxidizing emulsion systems. In future research, this question should be addressed for complex emulsions that are closer to real-life food products.