In this study, the intensity decrease in red fluorescence emission of BODIPY 665/676 was used to unravel droplet size-dependent spatial heterogeneity of lipid oxidation in WPI-stabilized emulsions. By modelling the kinetic rates of underlying lipid oxidation reactions, we showed that no perturbation of lipid oxidation occurs at the chosen low concentration of BODIPY 665/676. The kinetic model inferred that the decrease in red fluorescence of BODIPY 665/676 correlates with the increase of integrated peroxyl radical concentration over time. Microfluidic and colloid mill emulsification respectively result in mono-and polydisperse WPI emulsions. Kinetic curves of oxidation products of these oxidized emulsions, as observed locally by BODIPY 665/676 and in bulk by 1 H-NMR, can be explained by differences in droplet size distribution and heterogeneous packing of proteins at the droplet interfaces (Figure ). The different packing of proteins at the droplet interfaces of mono-and polydisperse WPI emulsions could be visualized by the accumulation of the CAMPO-AFDye 647 spin trap at droplet interfaces. Our results