To initiate lipid oxidation, 5 mM of 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) was added to the emulsions. 0.2 mL emulsion sample was added to 1.5 mL microcentrifuge tubes. The tubes were rotated horizontally at 2 rpm in a dark oven at 25 °C for up to 10 days. At sampling time points, two tubes per independently prepared emulsion were taken and either used directly for further measurements (imaging with CLSM) or stored under inert gas at -80 °C for at least 48 hrs for lipid extraction and, subsequently, quantification of lipid oxidation products.