Hypothesis:Plant seeds store lipids in oleosomes, which are storage organelles with a triacylglycerol(TAG) core surrounded by a phospholipid monolayer and proteins. Due to their membrane components,oleosomes have an affinity for the air/oil–water interface. Therefore, it is expected that oleosomes canstabilise interfaces, and also compete with proteins for the air–water interface. Experiments:We mixedrapeseed oleosomes with whey protein isolate (WPI), and evaluated their air–water interfacial propertiesby interfacial rheology and microstructure imaging. To understand the contribution of the oleosome com-ponents to the interfacial properties, oleosome membrane components (phospholipids and membraneproteins) or rapeseed lecithin (phospholipids) were also mixed with WPI.Findings: Oleosomes werefound to disrupt after adsorption, and formed TAG/phospholipid-rich regions with membrane fragmentsat the interface, forming a weak and mobile interfacial layer. Mixing oleosomes with WPI resulted in aninterface with TAG/phospholipid-rich regions surrounded by whey protein clusters. Membrane components or lecithin mixed with proteins also resulted in an interface where WPI molecules aggregated intosmall WPI domains, surrounded by a continuous phase of membrane components or phospholipids. We also observed an increase in stiffness of the interfacial layer, due to the presence of oleosome membraneproteins at the interface.