This study investigated the interfacial behaviour and viscoelastic properties of proteins at air-water interfaces in the presence or absence of salt. Pendant drop tensiometry, kinetic modelling, compression isotherms, Brewster angle microscopy (BAM), and dilatational rheology have been employed. Salt accelerates protein adsorption at the air-water interface, but it does not affect diffusion or rearrangement kinetics. The construction of compression isotherms revealed the formation of irreversible 2D networks, and BAM imaging showed microstructural faults. The elasticity and irreversibility of these films were confirmed using dilatational rheology, where the elastic modulus remained frequency-independent throughout the experimental window. Protein films were largely unaltered by salt in the linear viscoelastic range of the interface. However, notable effects were observed outside the linear viscoelastic range, where salt influenced mechanical responses, leading to strain-hardened interfaces. This study links the structural characteristics of canola protein to its functionalities, suggesting improvements in interfacial properties for sustainable foods