Understanding the behavior of protein surfactants at the oil-water interface is essential to the design of physicochemically stable emulsions. The objective of the study was to investigate the steric role of an interfacial membrane made of structurally modified pea protein with alkaline pH treatment (APP) in the oxidative stability of oil-in-water emulsions. Confocal laser scanning microscopy depicted more uniform and smaller oil droplets that had a reduced tendency to coalesce for emulsions prepared with APP than with native pea protein (NPP). Correspondingly, the APP emulsions were less prone to oxidation (malonaldehyde, peroxide) during storage. Similarly, cryo-transmission electron microscopy revealed more uniform air pockets with smoother undersurface that were surrounded by partially coalesced emulsions in whipped creams prepared with APP than with NPP. The improved interfacial properties and steric hindrance played a crucial role in the inhibition of oxidation in emulsions by alkaline pH-modified pea protein.