Inside, at the edge, and on the run; Dynamics of lipid oxidation in emulsions across length scales

Summary

Polyunsaturated fatty acids are key for a healthy diet, but they can oxidize, which negatively affects the product quality. This is particularly marked in oil-in-water emulsions, where oil is present as small droplets, such as mayonnaise, dairy/plant-based drinks, and infant formula. Currently, lipid oxidation is counteracted by expensive packaging concepts, storage at low temperatures, and (synthetic) antioxidants. Yet, unexpected fluctuations in the shelf life occur, so robust mitigation strategies are still missing.

The aim of this thesis was to understand the oxidative stability of emulsions, where we studied how colloidal structures across various length scales affect lipid oxidation reactions. We found that lipid oxidation increased systematically with decreasing droplet size due to favoured initiation reactions at the oil-water interface, and that oxidizing droplets interact, which influences the oxidation rate. Such findings will bring us in a much better position to predict and extend the oxidative shelf life of emulsion products.