Lipid oxidation is a major factor contributing to the deterioration of the sensorial quality of food products containing oil rich in unsaturated fatty acids. In many of these products, oil is dispersed as droplets in a continuous aqueous phase, 2 such as sauces, dressings, and infant milk. In these oil-in-water (O/W) emulsions, lipid oxidation is enhanced by the large interfacial area at which pro-oxidants present in the continuous aqueous phase are close to the lipids. Lipid oxidation can be mitigated by utilizing synthetic antioxidants, packaging the products in inert atmospheres, and storing products at low temperatures. Although these measures are very effective, the food industry faces pressure to develop alternative solutions. The main drivers are the need for a more sustainable supply chain and the clean labeling trend urging manufacturers to refrain from using synthetic antioxidants. Furthermore, benefits associated with cardiovascular health-promoting products with high levels of polyunsaturated fatty acids (PUFAs) such as omega-3 fatty acids are of increasing interest. However, PUFAs are particularly susceptible to lipid oxidation. All these aspects have rekindled the research interest in lipid oxidation and its prevention in O/W emulsions. Most of our current knowledge has been obtained using onedimensional methods that measure markers of lipid oxidation in an extracted oil phase. However, none of these methods capture the complexity of lipid oxidation kinetics occurring at the surface or within colloidal structures. The complexity of lipid oxidation in O/W emulsions from the perspective of location and time has urged the field to shift from one-dimensional to spatiotemporally resolved research approaches. To resolve the spatiotemporal aspects of lipid oxidation in food emulsions, confocal laser scanning microscopy (CLSM) is increasingly being deployed. Using CLSM and fluorescent BODIPY dyes enables the monitoring and localization of lipid oxidation as these BODIPY dyes undergo changes in absorption and emission spectra upon oxidation. For example, a recent publication using BODIPY 665/676 showed that oxidation in medium chain triglyceride (saturated fatty acids) emulsion droplets occurred faster when co-oxidizing unsaturated oil droplets were present. This may indicate that lipid oxidation can spread from oxidizing droplets to non-oxidized ones or that oxidizing droplets influence each other. A different study using the same fluorophore showed, however, that when lipid oxidation is selectively initiated in a single droplet, the oxidation does not spread rapidly to neighboring droplets. Recently, we used BODIPY 665/676 to show that the formulation of the emulsions determined the effect of droplet size on lipid oxidation in an O/W emulsion with a high oil concentration, such as mayonnaise. In that study, we combined information from monitoring local changes in BODIPY 665/676 fluorescence with local protein autofluorescence at the single-droplet level. Despite much ambiguity in the literature on the role of droplet size dispersion and heterogeneity of lipid oxidation, no systematic spatiotemporally-resolved investigation has yet been performed. Here we first mechanistically validate the use of BODIPY 665/676 to monitor local lipid oxidation in proteinstabilized emulsions. Then, using a quantitative kinetic reaction model, we assess the scope of using BODIPY 665/676 as a peroxyl radical monitor. Next, we focus on the spatiotemporal heterogeneity of lipid oxidation in mono-and polydisperse WPI-stabilized emulsions, respectively, prepared by a conventional method (colloid mill) and by microfluidic emulsification. By using the fluorescent spintrap CAMPO-AFDye 647, lipid and protein oxidation could be co-localized.